The effect of harvest timing and irrigation on the
quality of olive oil
by
Jamie Graham Ayton
A thesis submitted in partial fulfilment of the requirements for the degree of
Master of Science (Hons.)
University of Western Sydney
2006
Statement of Authentication
The work presented in this thesis is, to the best of my knowledge and belief, original
except as acknowledged in the text. I hereby declare that I have not submitted this
material, either in full or in part, for a degree at this or any other institution.
…… …….. (Signature)
Acknowledements
The majority of the work reported in this thesis was carried out at the NSW Department
of Primary Industries, Wagga Wagga Agricultural Research Institute, under the
supervision of the Principal Research Scientist (Oil Research), Dr Rod Mailer. I thank him for his guidance and support throughout this work. Thank you also to Damian
Conlan for his hard work, dedication and friendship.
I would like to thank Dr Tony Haigh and Dr Deidre Tronson from the University of
Western Sydney for their supervision, advice and support during the development of this thesis.
My thanks to my colleagues in the Oils Research Laboratories for their assistance in analysing the olive oil for this project.
I would like to thank the Rural Industries Research and Development Corporation and
Nugan Quality Foods for providing financial support for this project.
Many thanks to my family, especially my mother Kathleen, for their love and support.
Finally, thank you to my wife Gayle for her love, support, kindness and patience.
Abstract
Olive oil production in Australia has increased significantly in the past decade. and will soon reach about forty thousand tonnes per annum. While some Mediterranean countries have well established, modern olive oil industries, the Australian industry is still in its infancy. In order to compete in the world market, the Australian olive oil industry requires information on the response of olive cultivars in Australian conditions, especially when to harvest and irrigate to produce high quality olive oil
This study investigated the effect of harvest timing and irrigation on the quality of olive oil. It was conducted on a commercial olive grove in southern New South Wales over a three year period. It involved harvesting, extraction and analysis of the oil at 6 harvest times from early February to late July. Three commercial olive cultivars – Mission,
Paragon and Corregiolla were studied. The oil was analysed for free fatty acids, peroxide value, total polyphenol content, induction time, fatty acid profile, chlorophyll content and tocopherols. Results indicate that harvest timing has a significant effect on some of these components of the olive oil. Free fatty acids tended to increase as the season progressed, whereas polyphenols and hence induction time, or stability decreased significantly. A number of irrigation regimes were imposed in this study, although management was difficult due to drought conditions and lack of available water. Very few significant differences were found with irrigation effects.
This study provides very useful information and guidelines not only for the Australian olive industry, but also for the international olive oil producing community.
Glossary
AOCS – American Oil Chemists’ Society.
Crop evapotranspiration (ETC) – refers to crop water use. It is the combination of the water evaporated from the soil surface around the tree and that transpired from the trees foliage.
Crop coefficients (KC) – is an experimentally determined value for the measurement of the water use for a particular crop. It takes into account factors such as crop development, crop growth stages and canopy size.
EM31 electromagnetic survey probe – a device used to measure conductivity or resistivity of different parts of the soil profile.
Etp – potential crop evapotranspiration.
EU – European Union.
EVOO – extra virgin olive oil.
FFA – Free fatty acids.
FID – Flame ionization detector. A type of detector used in gas chromatography.
GC – gas chromatography.
HPLC – high performance liquid chromatography.
IOOC – International Olive Oil Council.
IUPAC - International Union of Pure and Applied Chemistry.
Malaxer – machinery used to mix the ground olives in order to separate the oil from the
solids. This is done at varying temperatures (20-35°C) and time periods (20 minutes to 1 hour) depending on the type processor and the cultivar being processed. This process is known as malaxation.
mEq – milliequivalents.
NATA – National Association of Testing Authorities.
Organoleptic – sensory characteristics of given products.
Pomace - the solids which remain after the oil has been extracted from the ground olives.
Regulated deficit irrigation (RDI) – RDI strategies allow a certain degree of water stress in periods when the tree is less sensitive to water deficit such as periods of lower temperatures and minimum plant growth. By applying these irrigation strategies, maximum yield can still be reached, while the amount of water applied is reduced.
TAG – triacylglycerol. A glycerol molecule to which are attached three fatty acids.
VSM – Volumetric soil moisture.
Table of Contents
1 CHAPTER 1 OLIVES AND OLIVE OIL...... 4
1.1 INTRODUCTION ...... 4
1.1.1 Family, species and tree type ...... 4
1.1.2 Fruit characteristics...... 5
1.1.3 Cultivars...... 5
1.1.4 World olive oil production and consumption ...... 5
1.1.5 Olive oil production and consumption in Australia ...... 7
1.1.6 Olive harvesting ...... 10
1.1.7 Postharvest storage ...... 11
1.1.8 Olive processing...... 12
1.2 CHEMICAL COMPOSITION OF OLIVE OIL...... 15
1.2.1 Fatty acids...... 15
1.2.2 Triacylglycerols...... 17
1.2.3 Polyphenols ...... 17
1.2.4 Chlorophyll...... 20
1.3 QUALITY PARAMETERS OF OLIVE OIL...... 21
1.3.1 Free fatty acids...... 21
1.3.2 Peroxide value...... 22
1.3.3 Accelerated oxidation tests...... 25
1.4 THE EFFECT OF HARVEST TIMING AND MATURITY ON OLIVE OIL QUALITY ...... 26
1.4.1 Fatty acid profile...... 28
1.4.2 Polyphenols ...... 29
1.4.3 Chlorophyll...... 30
1.4.4 Free fatty acids...... 31
1.4.5 Peroxide value...... 31
1.4.6 Accelerated oxidation tests...... 32
1.4.7 α-Tocopherols...... 32
1 1.5 THE EFFECTS OF DEFICIT IRRIGATION ON OLIVE OIL QUALITY ...... 33
1.5.1 Olive fruit development and irrigation...... 33
1.6 SUMMARY...... 37
1.7 AIMS AND OBJECTIVES...... 37
1.7.1 Aims...... 37
1.7.2 Objectives...... 37
2 CHAPTER 2 MATERIALS AND METHODS...... 38
2.1 WAGGA WAGGA OIL RESEARCH LABORATORY...... 38
2.2 GROVE SITE AND TRIAL PLAN...... 38
2.3 IRRIGATION...... 40
2.4 SOIL MOISTURE MONITORING...... 41
2.5 SAMPLE COLLECTION...... 42
2.6 MATURITY INDEX ...... 43
2.7 MOISTURE AND OIL ANALYSIS ...... 46
2.7.1 Moisture content...... 46
2.7.2 Oil content - cold press extraction ...... 46
2.8 OLIVE OIL QUALITY ...... 49
2.8.1 Total polyphenol content...... 49
2.8.2 Induction time...... 49
2.8.3 Fatty acid profile...... 50
2.8.4 Free fatty acids...... 50
2.8.5 Peroxide value...... 51
2.8.6 Chlorophyll...... 51
2.8.7 α-Tocopherols...... 51
3 CHAPTER 3 RESULTS AND DISCUSSION...... 53
3.1 INTRODUCTION ...... 53
3.2 CLIMATIC CONDITIONS AND EVAPOTRANSPIRATION ...... 54
3.2.1 Climatic conditions...... 54
3.2.2 Potential crop evapotranspiration ...... 54
3.3 IRRIGATION...... 56
2 3.3.1 Zone of root activity ...... 56
3.3.2 Crop water inputs...... 57
3.4 MATURITY INDEX ...... 60
3.5 MOISTURE CONTENT ...... 63
3.6 OLIVE OIL QUALITY ...... 69
3.6.1 Total polyphenol content...... 69
3.6.2 Induction time...... 82
3.6.3 Fatty acid profile...... 95
3.6.4 Free fatty acids (FFA)...... 100
3.6.5 Peroxide value...... 102
3.6.6 Chlorophyll...... 104
3.6.7 α-Tocopherol...... 106
4 CHAPTER 4 CONCLUSIONS AND FUTURE STUDIES...... 107
5 CHAPTER 5...... 111
5.1 REFERENCES ...... 111
6 CHAPTER 6...... 120
6.1 APPENDICES...... 120
3 1 Chapter 1 Olives and olive oil
1.1 Introduction
1.1.1 Family, species and tree type
The olive tree belongs to the Oleaceae family, genus and species Olea europaea L. (Lavee 1996). Other commercially significant trees belonging to the
Oleaceae family include lilac (Syringa), the jasmine tree (Jasminium) and the ash
(Fraxinus) (Robbelen et al. 1989). There is also a wild type of olive (Olea oleaster) commonly found in the Mediterranean area, which remains a very small shrub with tiny round fruit with very low oil contents (Lavee 1996).
Olive trees are best suited to a Mediterranean type climate where there is a long hot growing season with a cool winter (Connell 1994). The olive tree is an evergreen tree which is known to be able to tolerate dry weather, high soil salinity levels and infertile soil. The tree can vary in height from 2 to 20 metres depending on the type of cultivar and agronomic conditions. A major economic consideration in olive oil production is the fact that the olive tree is an alternate bearer, which leads to smaller commercial crops in alternate years in some cultivars, needing some type of intervention to minimize this (Boskou 1996; Lavee 1996).
The leaves of mature olive trees vary according to cultivar and seasonal conditions. The upper surface of the leaf is usually a dark green colour, while the lower surface is a whitish or silvery colour due to the presence of scales. The leaf shape also varies widely, narrow oblong to elliptic, according to the cultivar. The flowers of the olive tree are perfect, very small and white/yellow in colour.
4 1.1.2 Fruit characteristics
The olive fruit is a drupe consisting of an outer skin or exocarp, the mesocarp or flesh, and a hard woody inner stone or pit, which contains the seed (Delbridge 1982).
The fruit is normally oval shaped, although this depends on the cultivar.
The fruit contains up to 70% water, which is called vegetation water. This is also known to vary according to cultivar and environmental conditions. The mesocarp and exocarp are the edible parts of the fruit. These can contain up to 30% oil (Robbelen et al. 1989).
1.1.3 Cultivars
It is estimated that there are more than 2000 different olive cultivars. This is somewhat confounded by different cultivars being given the same name in different countries, or even regions within a country. The relative importance of a particular cultivar depends on many variables. These include the cultivar’s suitability to the climate, soil type and cultural practices of the regions in which it is grown. Other factors include resistance to disease and pests indigenous to the area, the purpose for which the fruit will be used (oil production, table olives or dual purpose), as well as the different flavours and textures favoured by the people of particular regions.
1.1.4 World olive oil production and consumption
The European Union (EU) is the largest producer of olive oil, accounting for approximately 74% of the world production between 1990 and 2000. Some 97% of
EU production comes from member countries Spain, Italy and Greece. World olive oil production averaged 2 071 200 tonnes per year between 1990 and 2000. In the decade from 1990-2000, world olive oil production increased from 1 828 200 to
2 314 200 tonnes per year (Luchetti 2002) (Figure 1.1). More recent figures indicate
5 world production reached 2 832 000 tonnes (provisional) in 2004/05. Approximately
78.6% of this olive oil was produced in EU countries
(http://www.internationaloliveoil.org).
World consumption averaged 1 882 400 tonnes during the period 1990-1995, increasing to 2 275 300 in the 1995-2000 period. The main consuming countries were from the EU, accounting for 72% of the total consumption (Figure 1.2)
(Luchetti 2002). Provisional figures from the 2004/05 season indicate world consumption of olive oil was 2 810 000 tonnes, with EU countries accounting for
71% of consumption (http://www.internationaloliveoil.org).
Olive oil is a very important commodity on the world market. Olive oil accounts for only 2% of the world trade in edible vegetable oils, compared with palm oil, which accounts for 45% of the world trade. In terms of value however, olive oil accounts for 30% of trade, compared to 30% for palm oil (Luchetti 2002).
Others 3% Turkey Algeria 4% Tunisia 2% 8% Syria 4% Morocco 3% France Spain 0% 33% Portugal 2%
Greece 17%
Italy 24%
Figure 1.1 Average world olive production: 1990-2000 (Luchetti 2002).
6
Others USA Algeria 8% 6% 2% Turkey 3%
Tunisia 3% Syria 4%
Morocco 2% EU 72%
Figure 1.2 Average world olive consumption : 1990-2000 (Luchetti 2002).
1.1.5 Olive oil production and consumption in Australia
Olea europaea was first introduced into Australia in December 1800 by
George Suttor, a London market gardener, who arrived in Sydney with an olive tree sent by Sir Joseph Banks (Spennemann 1999; Spennemann and Allen 2000).
Much of the Australian continent is situated between latitude 25° and
45° South, the Southern Hemisphere equivalent of the traditional olive growing regions in Europe, namely the Mediterranean climate. This includes semi-arid to subhumid regions, with hot dry summers and winter dominant rainfall. Areas of
Australia with this type of climate include south-western Western Australia, south- eastern South Australia, south-western New South Wales and some parts of Victoria
7 (Table 1.1) (Smyth 2002). Thus olive groves have been planted in these areas (Figure
1.3).
Table 1.1 Distribution of olive trees in Australia (Miller 2002). Number of olive trees State % of total (approx.)
Victoria 2 300 000 27
New South Wales 2 000 000 23
South Australia 1 500 000 17
Western Australia 1 300 000 16
Queensland 1 200 000 14
Tasmania 170 000 2
Northern Territory 5 000 <1
Figure 1.3 Map of Australia showing areas of the country with climate similar to the
traditional olive growing regions in Europe (shaded)
(www.australianolives.com.au/growing/factsheet.html).
8 While there have been a number of attempts to develop a commercial olive industry in Australia over the last 200 years, it is only in the last decade that this has been successful. While difficult to predict, it is estimated that 8.5-9 million trees, representing about 39 000 ha, have been planted since 1995. It is estimated
Australian olive oil production will reach 40 000 tonnes by 2008 (Miller 2002).
Due to recent research proclaiming the health attributes of olive oil (Tuck and Hayball 2002), as well as the promotional activities by the IOOC, olive oil consumption in Australia has increased. Olive oil imports have increased from approximately 13 000 tonnes in 1990/91 to approximately 31 000 tonnes in 2002/03
(Figure 1.4) (IOOC undated).
35000 Imports 30000
25000
20000
15000 Tonnes
10000
5000
0 90/91 91/92 92/93 93/94 94/95 95/96 96/97 97/98 98/99 99/00 00/01 01/02 02/03 Year
Figure 1.4 Olive oil imports into Australia 1990-2003 (compiled using data from IOOC, undated).
9 1.1.6 Olive harvesting
Two important aspects of olive grove management are knowing when to harvest and how to harvest the fruit for optimal quality and yield. The decisions made will have major effects on the yield and quality of the olive oil produced.
Traditionally, determining when to begin harvesting has relied upon factors such as fruit colour or adherence to particular dates each year, as well as other practices that have been passed down through the generations.
Harvesting methods range from traditional manual methods to mechanical harvesting techniques. In some areas, nets are placed beneath the tree and the fruit is allowed to fall naturally, with the fruit being collected periodically from the nets.
Manual picking is the oldest method of harvesting olives. It is probably the least harmful method for the tree, although it is slow and expensive. In some areas sticks are used to beat the branches of the tree to dislodge the fruit, with the fruit falling onto nets or mats placed around the tree. Pneumatic rakes are also used to remove the fruit.
Most mechanical harvesting is carried out using multidirectional shakers, which use a vibrating head clamped to the tree that transmits the vibration through the tree at a particular frequency, thus shaking the fruit from the tree. There are some disadvantages in this system, including the cultivar’s resistance to shaking and damage to the tree at the attachment point of the shaker.
Other methods of mechanical harvesting have been developed. Machines with finger-like probes on rolling drums have been developed as an alternative to mechanical shakers. Over-the-row harvesters, similar to those being used in the wine industry, are also being developed. Disadvantages of these type of harvesters include damage to the foliage on the tree, which may lead to a lower yield the following year, as well as the need to constantly prune the trees to a suitable shape for the
10 harvester to pass over. The orchard terrain must also be such that it allows access and movement of the machinery associated with mechanical harvesting (Tombesi 1990;
Lopez-Villalta 1996).
1.1.7 Postharvest storage
In some countries, such as Spain, the olive production exceeds the processing capacity of the mills, requiring the olives to be stored before they can be processed.
In Australia, there are a limited number of olive mills, which are separated by vast distances, requiring the fruit to be stored and transported for processing after harvest.
During this storage period, the cell structure can begin to break down due to the action of microorganisms and mechanical damage due to compression of stacked fruit. This can be accelerated by increased temperatures, fermentation of the fruit, maturity of fruit and disease (Pereira et al. 2002).
Olive oil obtained from damaged olives is characteristically high in undesirable components such as free fatty acids (Figure 1.5), and can also develop high levels of volatile acids such as butyric or acetic acid, which cause a musty smell. The oil is no longer classed as extra virgin olive oil and needs to be refined before consumption, increasing production costs and decreasing market value
(Garcia et al. 1996a; Tayfun Agar et al. 1998).
Some of these problems can be avoided by storing the fruit waiting for processing in shallow, ventilated containers, at low temperatures, such as 8°C or below.
11 H H O H C OH HCOCR 1 Enzymes or acid (heat,stress, O O cell breakdown) HOC H+ 3 X OH C R H C O C R2
O
HOC H H C O C R3
H H
Triacylglycerol Glycerol Free fatty acids
Figure 1.5 Schematic diagram showing the breakdown of triglycerides to form free fatty acids (Lawson 1995).
1.1.8 Olive processing
Leaf removal and washing of the olives is important in processing olive oil.
Contaminants, whether vegetable or non-vegetable, can introduce undesirable characteristics into the oil. The presence of leaves creates an excessively bitter ‘green leaf’ organoleptic characteristic. If soil is introduced onto the fruit during harvest and not removed, an ‘earthy’ sensory defect will be present in the oil, lowering the quality and therefore the market value. To avoid this, the fruit is passed through a powerful aspirator, which removes leaves and twigs. The olives are then passed through a tank of water, or a tube with high-pressure water, to remove other contaminants (Harwood and Aparicio 2000a).
There are a number of methods used for crushing olives in order to release the oil. Traditionally stone mills have been used, usually coupled with a pressing system for extraction. More recently, modern systems have been developed which employ metallic crushers such as fixed hammers, toothed discs, cones or rollers.
12 These more modern crushers are more efficient than the stone mills as they allow for continuous processing using 2 or 3 phase centrifuges. The stone mill coupled with a pressing system is discontinuous and slow (Boskou 1996).
Following crushing, the olive paste is mixed in a process called malaxation in order to obtain maximum oil yields. The paste is stirred slowly (40rpm) and continuously by horizontal or vertical shafts with inclined or spiral shaped blades.
The walls of the malaxation tank are heated with either electrical elements or circulating hot water in order to heat the olive paste.
If the pressure system is to be used to extract the oil, the malaxation time is
10-20 minutes at 20-25°C (Di Giovacchino et al. 2002). When the olive mill uses hammer mills or similar crushers, the violent crushing operation causes the formation of emulsions between oil and water. In order to break these emulsions, the malaxation of the paste is usually carried out at 25-35°C for 1 hour or more
(Harwood and Aparicio 2000a).
After malaxation the oil needs to be separated from the pomace. There are a number of different techniques used to do this. As already mentioned, if a stone mill is used for crushing, the oil is usually extracted by the pressing method. In this system, the olive paste is spread on synthetic fibre mats. Three to 5 of these mats are then placed between 2 metal discs. A number of these stacks are placed in an hydraulic or screw type press. As pressure is applied the ‘oily must’ (oil and vegetable water) is separated from the pomace. The oily must is then separated using a simple centrifuge to produce the olive oil. This method is one of the oldest methods used to separate olive oil and although it is used in some smaller mills due to its low capital costs and relatively simple machinery, the process has largely been superseded (Boskou 1996; Harwood and Aparicio 2000a; Di Giovacchino et al.
2002). 13 Centrifugation, since its development in the late 1960s, has become the most widely used method of olive oil separation. This method involves the use of three- phase horizontal centrifuges (also known as decanters). The paste from the malaxer is centrifuged at high speed (3500-3600rpm), which increases the differences between the specific weights of the liquids (vegetable water and oil) and the solids.
Lukewarm water is added to the paste in the decanter in order to increase the fluidity of the mixture and favour the separation of the liquid and solid phases by the centrifugal forces. The best oil yield results occur when the olive paste/water ratios are between 1:0.6 and 1:1. The vegetable water is then separated from the oil in vertical centrifuges. The disadvantages of this method include the high cost of the machinery and the large amounts of vegetable water produced. The organoleptic properties and chemistry of the oil can be compromised, in that some polyphenols and volatiles are lost in the process (Harwood and Aparicio 2000a). In order to overcome some of these problems, a dual phase decanter was developed in the late
1970s. Dual phase decanters work on the same principle as the three phase decanters, except little or no water is added prior to centrifugation. This allows the retention of more polyphenols and volatiles, and the reduction of vegetable water waste, which is very difficult to dispose of (Boskou 1996).
Another extraction system is the percolation, or selective filtration system. In this system, steel plates are plunged into the olive paste. When the plates are withdrawn, the oil coats the plate due to the interfacial tension of the oil being less than that of the vegetation water. The oil drips off the plates into collection tanks, hence the process is called percolation or drippage. This system was first developed in about 1911 and is still used today (Di Giovacchino et al. 2002).
Each of these extraction systems has certain advantages and disadvantages.
The centrifugation method tends to produce oil with low polyphenols levels due to
14 the addition of water in the processing, which removes some of the water soluble antioxidants. The pressure extraction system involves many interruptions in the processing which can lead to organoleptic defects in the oil (Cert et al. 1999).
1.2 Chemical composition of olive oil
The composition of olive oil is primarily triacylglycerols (98.5-99.5%), with the remainder being made up of minor components such as polyphenols, chlorophyll, tocopherols and sterols. Although these minor components, commonly known as the unsaponifiable matter, make up only a small portion of the total, they are very important in that they contribute greatly to the oil’s stability and organoleptic characteristics, because extra virgin olive oil is consumed without refining (Harwood and Aparacio 2000b).
1.2.1 Fatty acids
Fatty acids are long chain carbon molecules with a carboxyl group at one end. Fatty acids are classed as saturated when there are single bonds between each carbon in the chain. When there is one double bond in the structure it is said to be monounsaturated, while two or more double bond in the structure is termed polyunsaturated (Figure 1.6). Saturated fatty acids are very stable, while monounsaturated and polyunsaturated fatty acids are less stable due to the more reactive double bonds in their structure.
15 H H H H H H HHHHHHHH H H H O R C C C C C C CCCCCCCC C C CC H H H H H H H H H H H H H H H OH
Figure 1.6 Structure of a typical fatty acid (oleic acid). This structure contains one double bond, hence it is known as a monounsaturated fatty acid. The carboxylic acid functional group is attached to the ester bond to the glycerol molecule in a triacylglycerol molecule
(Lawson 1995).
The main fatty acids in olive oil are oleic acid (C18:1) (this means 18 C-atoms with one double bond), linoleic acid (C18:2) (18 C-atoms, 2 double bonds), palmitic acid
(C16:0), stearic acid (C18:0), linolenic acid (C18:3), and palmitoleic acid (C16:1).
Other fatty acids present in trace amounts include myristic acid (C14:0), heptadecanoic acid (C17:0), heptadecenoic acid (C17:1), arachidic acid (C20:0), eicosenoic acid (C20:1), behenic acid (C22:0) and lignoceric acid (C24:0).
The analysis of fatty acids in edible oils by gas chromatography (GC) is a routine procedure carried out in laboratories worldwide. In this procedure, the fatty acids are converted into methyl esters and then analysed using a GC with a flame ionisation detector (FID). Once the fatty acids are separated, they can be quantified using specialist software (Harwood and Aparicio 2000b).
Many factors affect the fatty acid composition of olive oil including cultivar, country or region of production, climate, soil type and stage of maturity of the olives
(Boskou 1996).
16
1.2.2 Triacylglycerols
A triacylglycerol, or TAG, is a molecule which consists of a glycerol molecule to which are attached three fatty acids (Figure 1.5) (Lawson 1995). The bond between the alcohol groups of glycerol and the carboxylic acid groups of the fatty acids is called an ester bond.
The major triacylglycerols in olive oil are OOO (40-60%), POO (10-20%),
OOL (10-20%), POL (5-7%), and SOO (3-7%) ( O= Oleic, L= Linoleic, P =
Palmitic, S = stearic acids). The biosynthesis of the triacylglycerols in olives generally follow the 1,3 random distribution. This means the fatty acids on the triacylglycerols are randomly distributed in the 1 and 3 positions on the molecule.
Oleic and linoleic acids, the main unsaturated fatty acids found in olive oil, are esterified preferentially in the 2 position of the triacylglycerols (Boskou 1996).
Typically, triacylglycerols are measured using reverse phase high performance liquid chromatography (RP-HPLC). The method is based on the separation of triacylglycerols into size: each peak on the chromatogram represents a fatty acid with a particular number of carbon-atoms in its chain, and subsequent quantification is attained by measuring the area under these peaks (Harwood and
Aparicio 2000b).
1.2.3 Polyphenols
Polyphenols are present in considerable amounts in virgin olive oil, and have a substantial effect on the stability, sensory and nutritional characteristics of the oil
(Jesus Tovar et al. 2001a).
17 Polyphenols, or phenolic compounds, are substances that contain a benzene ring with one or more hydroxy groups including functional derivatives which include esters, methyl esters and glycosides (Tsimidou 1998).
Polyphenols are present as phenolic acids (caffeic, p-coumaric, ferrulic, p- hydroxybenzoic and vanillic acids) as well as phenolic alcohols (tyrosol and hydroxytyrosol) in olive oil (Koprivnjak and Conte 1998). The prevalent phenolic compounds are secoiridoid derivatives (Servilli et al 1999), which are derived from oleosides (Soler-Rivas et al. 2000) (Figure 1.7).
18 CH CH COOH
CH2CH2OH
OH
OH OH
Caffeic Acid Tyrosol
OH O
CH2 CO CH2 CH2 OH O
CH3 O C CH CH3
O OH
Oleuropein aglycon(e)
Figure 1.7 Chemical structure of common polyphenols, the phenolic acid caffeic acid (3,4-
dihydroxycinnamic acid); the phenolic alcohol tyrosol (4-hydroxy-phenethylalcohol and the
secoiridoid oleuropein aglycon(e) ((3,4-dihydroxyphenyl)ethanol derivative).
For the past thirty years the contribution of polyphenols to the shelf life of olive oil has been thoroughly investigated. Through this research the relationship
19 between oxidative stability and the concentration of polyphenols has been well established (Aparicio and Luna 2002). The redox properties of polyphenols allow them to act as hydrogen donors and singlet oxygen quenchers, hence their role as antioxidants (Jesus Tovar et al. 2001a). Polyphenols are also responsible for the bitterness perceived in olive oil.
Some polyphenols can play a significant role in human nutrition in that they exhibit protective activities, including on the liver (preventing liver cirrhosis), prevention of atherosclerosis plaques, as well as decreasing lipids and cholesterol in blood (Koprivnjak and Conte 1998).
1.2.4 Chlorophyll
Extra virgin olive oil can range in colour from very green to gold, depending on the amount of pigment present (Boskou 1996). Chlorophyll pigments are known to be responsible for the green hues present in the oil. Chlorophyll concentrations in olive oil are dependant on a number of factors such as fruit maturity, the extraction process and storage conditions (Psomiadou and Tsimidou 2001). Normal chlorophyll concentrations in olive oil range from 0 to 20ppm. Colour can be an important factor to the consumer when purchasing the product. Chlorophyll pigments in olive oil include chlorophyll a and b and pheophytin a and b (a derivative of chlorophyll). Of these, pheophytin a is the predominant pigment usually accounting for 70-80% of the total pigments.
Chlorophyll pigments are important in the stability of olive oil, in that they act as pro-oxidants in the presence of light, and anti-oxidants when the oil is stored in the dark (Gutierrez Rosales et al. 1992a; Koprivnjak and Conte 1998; Ryan et al.
1998; Salvador et al. 1998; Salvador et al. 1999; Psomiadou and Tsimidou 2001;
Psomiadou and Tsimidou 2002). The pro-oxidant effect, or photo-oxidation, occurs
20 when the oil is exposed to light. When the light strikes the oil a series of rapidly progressing oxidation reactions is initiated (Gutierrez Rosales et al. 1992a).
Chlorophyll derivatives, known as photosensitisers, need to be present to promote these reactions as they capture and concentrate the light energy (Psomiadou and
Tsimidou 2001). This energy is transmitted to the oxygen present, converting it to a singlet state that reacts directly with the double bond of the fatty acids. Oxygen is inserted on either side of the two carbons of the double bond, resulting in an allyl hydroperoxide, an unwanted by product (Gutierrez Rosales et al. 1992b). The anti- oxidative behaviour of chlorophyll in darkness is not well understood. It is believed that chlorophyll probably acts by quenching free radicals.
Analytical procedures used to measure chlorophyll content in olive oil include measuring the absorbance at 670nm, as well as separating the individual pigments using HPLC (Ryan et al. 1998).
1.3 Quality parameters of olive oil
1.3.1 Free fatty acids
Free fatty acids (FFA) result from the action of lipases (enzymes which destroy triacylglycerols) in the oil, or other hydrolytic activity which occurs during processing. A low concentration of FFA in olive oil is expected to be due to metabolism (Ryan et al. 1998). However, elevated levels can occur when certain conditions are present. If the fruit is harvested late in the season, or the fruit is stored for a long time before processing, cell degradation will promote the release of lipases from the cell and the concomitant production of free fatty acids. When hydrolysis occurs, the bond between the glycerol and the fatty acid is broken. High temperatures
21 and pressures, as well as excessive amounts of water, accelerate hydrolysis (Figure
1.5) (Lawson 1995).
The most common method for the determination of free fatty acids is performed using acid/base titrations with phenolphthalein as an indicator. The oil is dissolved in an organic solvent and titrated with an alkaline solution such as sodium hydroxide. The results are reported as %FFA as oleic acid (Garcia et al. 1996b).
1.3.2 Peroxide value
Lipid oxidation or auto-oxidation occurs when oils are exposed to oxygen in the air. This is undesirable because it affects the sensory qualities of the oil, as rancid odours are produced as a consequence of oxidation. The rate of oxidation depends on the degree of saturation of the fatty acids, as well as the amount of antioxidants present
Lipid oxidation occurs if three conditions are present:
1. presence, as well as accessibility of oxygen;
2. presence of unsaturated bonds in the fatty acid structure; and
3. presence of catalysts.
Oxidation takes place by a free radical mechanism. This involves the process of initiation, propagation and termination (Figure 1.8).
During the initiation phase (1) an unsaturated fatty acid reacts with oxygen, involving a catalyst such as light, heat, metal ions (copper or iron), peroxides or the enzyme lipoxygenase. This leads to the formation of a free radical. These free radicals are very reactive as they have an unpaired electron, and react with oxygen immediately upon exposure. A hydroperoxide radical is formed from the reaction of oxygen with these free radicals (2). This leads to propagation. During propagation, hydroperoxide radicals react with other fatty acids creating hydroperoxides (ROOH)
22 (3) (Koprivnjak and Conte 1998). Once hydroperoxides are formed initiation reactions proceed easily.
As hydroperoxides decompose a wide variety of aldehydes, ketones, and hydrocarbons are formed. These are the compounds responsible for the rancid odours and flavours (Lawson 1995). The termination process occurs when two radicals are combined, so that their electrons ‘pair up’ to form a chemical bond (4-6).
Initiation
1. 2RH + O2 2R° + 2OH°
Propagation
2. R°+ O2 ROO°
3. ROO° + RH ROOH + R°
Termination
4. R° R° + R -R
5. R° + ROO° ROOR
6. ROO° + ROO° ROOR + O2
RH – unsaturated fatty acid in which the H is attached to a carbon adjacent to a double bond
R° - free radical formed in the reaction (alkyl radical)
ROO° − hydroperoxide radical
ROOH - hydroperoxides
Figure 1.8 Oxidation takes place by a free radical mechanism. This involves the process of initiation, propagation and termination (Boskou 1996; Koprivnjak and Conte 1998).
23 A method used to determine lipid oxidation is to measure the peroxide value, which is indicative of the amount of hydroperoxide in the oil. The standard method for measuring peroxide value is to titrate a mixture of the oil, chloroform, acetic acid and saturated potassium iodide solution with sodium thiosulphate. The reaction which takes place during the measurement is shown in Figure 1.9. This reaction is convenient, in that although there are a seemingly complicated sequence of reactions, it serves as its own indicator - the I2 forms a blue colour with a starch indicator, and the end-point can easily be detected when this blue colour disappears upon the titration with sodium thiosulphate.
+ - ROOH + 2H + 2I I2 + ROH + H2O
2- 2- - I2 + 2S2O3 S4O6 + 2I
where ROOH is the lipid hydroperoxide
Figure 1.9 The reaction which takes place when measuring peroxide values in oil. (Robards et al. 1988).
Presence of peroxides indicates the extent of oxidation which has occurred in an oil or fat. International Olive Oil Council standards dictate that the peroxide value must be less than 20 meq of active oxygen/Kg oil for classification as extra virgin olive oil (EVOO).
Factors which affect oxidation rates in olive oil after processing and during storage include exposure to air, light and the presence of free fatty acids. The water,
24 metal ion and sediment content of the oil also has a significant effect on the rate of oxidation.
1.3.3 Accelerated oxidation tests
In order to evaluate the resistance of olive oil to oxidation, certain methods are used in order to accelerate the oxidation process. The sample is heated and exposed to oxygen to initiate oxidation, and the formation of hydroperoxides is measured, either by titration or electronically. Accelerated oxidation tests are measured in a unit known as “induction time". Induction time is a term used to indicate the relative stability of an oil, or its resistance to oxidation. A common electronic test is the Rancimat procedure, in which the oil is heated and air is pumped into the sample. The hydroperoxides formed during oxidation produce a series of secondary products such as carbonyl compounds and alcohols, which are further oxidised to carboxylic acids; mostly formic acid and acetic acid. These volatile acids are then trapped in distilled water. Because these acids dissolve in water to produce ions, the conductivity increases as oxidation proceeds. Using the
Rancimat procedure, the change of conductivity is plotted and the induction time of the oil is determined as the point of inflection on the electronically recorded oxidation curve (Figure 1.10).
Accelerated oxidation tests are useful for comparing the relative stability of different oils but they cannot be used to predict exact shelf lives or ‘use-by’ dates of the oils before they begin to deteriorate (Kiritsakis et al. 2002; Velasco and
Dobarganes 2002).
25 environments,varieties, seasons manage and requiredpractices obtain to knowl the have donot growers therefore varieties.commercial from of range a times harvest establish to cultivars and optimum an time harvest for optimal harvest time. illustrates This determine to need the the of quality o olive best ofthe not is countries th (1996b)suggests that al. et 1.4 oxidation procedure. Figure 1.10.
Harvest timingHarvest major has a impact onthe The rate, evenness rate, The time and of vary will ripening significantly between industry olive Australian The th in is The effect ofharvesttiminga The effect Conductivity Typicalinduction timegraph produced fromtheRancimat accelerated commercial fru as the quality, the highest possible quality and yield of olive oil. oil. ofolive yield and quality possible highest the e majoritye (9 oil ofolive Induction time edge and experience in management in experience and edge nd maturityonoliveoilquality e initiale stages of development and ment practices. Studies practices. ment into Europe in quality of olive oil produced. Garcia Garcia produced. oil ofolive quality 4%) produced in European European in 4%) produced it has not been picked at the the at picked been has not it Time point Inflection
il il 26 management practices such as harvest timing are often highly specific in terms of location and local genotypes and therefore of limited use for broader interpretation and application (Tombesi 1990; Giametta 1992; and Rahmani et al. 1997). Hence, there is a strong demand for information on the response of commercial cultivars to
Australian conditions and the effects of time of harvest and irrigation management practices.
As olive production increases as a result of the massive plantings that have taken place in Australia in recent years (Table 1.1; Figure 1.3), olive oil sales will need to be more competitive. Although yield is of major importance, the significance of oil character and quality are gaining recognition. Already, olive oil competitions are in abundance in every state in Australia with many commercial bottles now carrying medals to indicate the quality. Consumers are increasingly understanding the importance of oil stability and oil that oxidises quickly will be unacceptable to consumers. Also of major importance are the nutritional benefits of monounsaturated oil with naturally low levels of saturated fatty acids (Wahrburg et al. 2002). Growers and processors can have significant controls over all of these factors through monitoring crop maturity and adapting harvesting and processing management to suit their requirements.
Studies under Australian conditions are required to pinpoint the stage of maturity, and morphological indicators, that the grower might use to determine the quality and style characteristics obtained from harvesting fruit at particular times during ripening. Harvest monitoring guidelines would focus on achieving customer requirements for extra virgin olive oil.
There are many stages in the growth cycle of olive fruit. Olive reproductive growth begins with flower induction on current season’s shoots, usually around
December each year in Australia. After induction, the flower bud remains dormant
27 until autumn. Flower bud initiation occurs in autumn (April/May). At this time the microscopic flower bud begins to develop. About 8 weeks before flowering (late winter) flower bud differentiation takes place. The flower bud begins rapid development and growth, and in October/November, flowering and fruit set takes place. About 3-4 weeks after full bloom, infertile flowers abscise and fruit set takes place. About 6-8 weeks after full bloom (late December/early January), the endocarp, or pit, enlarges to full size and hardens. The fruit continues to mature from January through June, with ripening occurring from April to June in most olive growing areas of Australia.
Understanding the growth cycle of the olive fruit is important, as changes in conditions at any time in the cycle can have a significant influence on the yield and quality of the olive oil produced (Ferguson et al.1994; Lavee 1996).
As mentioned, the maturation of olive fruits takes place over several months.
The rate of maturation depends on a many factors such as cultivar, growing region, climatic conditions and fruit load (Salvador et al. 2001). The degree of maturation,
(ripene ss) of the fruit, can both directly and indirectly influence the quality and flavour of the oil. Therefore, in order to gain optimal oil quality, an optimal harvest period needs to be determined (Caponio and Gomes 2001).
1.4.1 Fatty acid profile
The influence of maturity on the fatty acid profile of olive oil has been studied widely, with differing opinions of its effect. Gimeno et al. (2002) concluded that the level of maturity of the olives did not have a significant effect on the fatty acid profile of olive oil, however they acknowledged that the maturity range of the fruit used in their study was somewhat limited. Gutierrez et al. (1999) obtained similar results to this author (Ayton et al. 2001), wherein changes in the fatty acid
28 profile were observed as the maturation of the fruit progressed. The concentration of palmitic acid (C16:0) decreased during ripening. Gutierrez et al. (1999) explain that this is probably the result of a dilution effect, and that the absolute palmitic acid content remained constant, but the level of oleic acid (C18:1) increased due to active triacylglycerol biosynthesis. Linoleic acid (C18:2) levels were found to increase during ripening. This can be explained by the fact that as oleic acid (C18:1) is forming, the enzyme oleate desaturase is active, transforming oleic acid to linoleic acid. The concentrations of the other major fatty acids, palmitoleic acid (C16:1), stearic acid (C18:0) and linolenic acid (C18:3) remain relatively stable during the normal commercial harvesting period.
1.4.2 Polyphenols
The level of phenolic compounds in virgin olive oil is an important factor in evaluating its quality, as the polyphenols increase the oxidative stability of the oil, as well as being respons ible for the pungency and bitterness in the oil (Gutierrez
Rosales et al. 1992b).
Most researchers, such as Paz Romero et al. (2003), have observed that the levels of total polyphenols decline as the olive fruit ripens. Skevin et al. (2003) suggest that this occurs because, during ripening, the activities of the esterase enzyme s present cause the degradation of oleuropein (Figure 1.7), the main phenolic compound in unripened fruit, leading to the formation of compounds which are both phenolic and non-phenolic in nature.
Environmental conditions such as ambient temperature and water availability have a significant influence on the maturation rate of the olive fruit (Skevin et al.
2003). Low water availability creates a stress situation that induces the production of phenolics (Parr and Bolwell 2000). This explains why some researchers have found
29 that crop season has the greatest influence on the polyphenol content of the oil, especially when climatic conditions varied from year to year (Paz Romero et al.
2003; Skevin et al. 2003).
1.4.3 Chlorophyll
While measurement of chlorophyll concentration in olive oil is not required by IOOC regulations, it is important for a number of reasons. Chlorophyll is implicated in autoxidation and photo oxidation mechanisms, therefore affecting the oxidati ve stability of t he oil. Colour is also an important attribute to consumers, who associate the green hues from the chlorophyll in the oil with freshness of product
(Ryan et al. 1998).
The chlorophyll content of olive oil has been shown to decrease markedly during ripening (Gutierrez et al.1999; Skevin et al. 2003). Some researchers have found the concentration can be as high as 80 mg/Kg oil very early in the ripening period, falling to about 2 mg/Kg oil when the fruit is very ripe (Salvador et al. 2001).
As with polyphenols, climate has an important role in the chlorophyll concentration of olive oil as it influences the rate of ripening of the fruit. Morello et al. (2003) showed that freeze damage during the harvest period has a significant effect on the chlorophyll content of olive oil, leading to decreased concentrations.
During frosts, destruction of the cell membranes in the fruit occurs as a consequence of ice crystals forming inside the cells. This allows contact between enzymes and their substrates, promoting changes to the composition of the fruit and subsequent changes in quality of the olive oil.
30 1.4.4 Free fatty acids
Factors that increase free fatty acid content in olive oil include bruising of the fruit, insect damage and incorrect postharvest storage. This type of mechanical damage causes cell destruction, exposing the oil to lipase from within the cell, or other types of hydrolytic activity, thus causing increased free fatty acid concentrations. Research has shown this increase can be cultivar dependent, as some cultivars ripen more quickly than others, leaving them more susceptible to damage
(Garcia et al. 1996b; Gutierrez et al. 1999; Koutsaftakis et al. 2000). In almost all cases the free fatty acid content cited by researchers remains well below the IOOC limit of 0.8%.
1.4.5 Peroxide value
While it is generally understood that the degree of oxidation, and hence the peroxide value, is affected to a greater extent by processing and storage conditions
(Garcia et al. 1996a), th e influence of fruit maturity has also been examined. Some researchers (Gutierrez et al. 1999; Salvador et al. 2001) have found that the peroxide value decreased markedly during fruit ripening. This behaviour is explained by a decrease in lipoxygenase activity as ripening progresses. The lipoxygenase pathway is a cascade of biochemical reactions which occur in most plant tissue, including olives. This pathway is responsible for the generation of the most important volatile constituents of the aroma of olive oil. In general terms, this pathway involves a series of enzymes that oxidise (by lipoxygenase) and cleave (by hydroperoxide lyase) polyunsaturated fatty acids to yield aldehydes, which are subsequently reduced to alcohols (by alcohol dehydrogenase), which can, in turn, be esterified (by alcohol acyltransferase) to produce esters. The lipoxygenase pathway is stimulated by tissue damage, such as upon crushing of the olives. As the activity of these enzymes
31 decreases due to denaturation as the fruit becomes over ripe, the lipoxygenase activity also decreases. Paz Romero et al. (2003) and Rahmani et al. (1997) reported little change in the peroxide value during their harvest period, although the limited harvests which they performed (two and three respectively) over a shorter period than the other researchers could explain the difference between their results and others.
1.4.6 Accelerated oxidation tests
The values measured in accelerated oxidation tests, such as the induction time measured by the Rancimat method, are closely correlated with the polyphenol content of the oil (Salvador et al. 1998). As with polyphenols, most researchers report a decrease in the induction time as ripening progresses, due to progressive deterioration of the fruit, as well as the decline in total polyphenol content, as polyphenols protect against oxidation (Koutsaftakis et al. 2000).
1.4.7 α-Tocopherols
Tocopherols, also known as Vitamin E, contribute to the stability of olive oil due to their antioxidant properties. They are also beneficial to humans due to their role as radical quenchers (Boskou 1996). Total tocopherol content is reported to be between 100 and 300 mg/Kg oil for most commercial olive oils (Andrikopoulos et al.
1989). Tocopherol concentration is significantly reduced towards the end of the harvest period. Tocopherols occur in olive oil only in the free (nonesterified) form
(Boskou 1996).
32 1.5 The effects of deficit irrigation on olive oil quality
Although olive trees are considered to be drought tolerant, in order to achieve
maximum oil yield and quality, they may need additional irrigation under drought
conditions.
Early research in Europe and the United States has showed that oil yield and
quality improvements could be achieved with constant irrigation in order to maintain
good soil moisture levels throughout the season (Tovar et al. 2002), a practice which
has been adopted by the Australian olive industry. Under typical Australian
conditions, this can lead to a water requirement of about 10 megalitres per hectare
each year (Lantzke and Taylor 2001), a large requirement, especially when water
resources are scarce. Recent research has shown that regulated deficit irrigation
(RDI) can be used to maintain yield and quality, while reducing water requirements
substantially (Inglese et al. 1996; Patumi et al. 1999; Jesus Tovar et al. 2001b).
1.5.1 Olive fruit development and irrigation
Olive fruit development goes through 5 main stages (Figure 1.11) (Lavee 1996).
Crop management at each of these stages was reported to have an effect on the
eventual yield and quality of the olive oil produced.
I. Fertilization and fruit set. Rapid early cell division involves growth of the embryo
(stage I). Enlargement of the new fruits becomes noticeable after about two weeks.
A large number of fruit and flower parts are dropped in this stage, and severe
moisture stress imposed on the tree will increase the level of abscission and reduce
the crop potential. When flowering starts in early November this period lasts until
late November to early December.
33
3.5
3 V IV 2.5 III II 2 I 1.5
Fruit weight (g) 1
0.5
0 0 30 60 90 120 150 180 210 days AFB
Figure 1.11 Schematic graph of olive fruit growth and stages of fruit development
corresponding to days after full bloom (AFB) (adapted from world olive encyclopaedia, Lavee
1996).
II. Seed ( endocarp) development. With early to mid November flowering, stage II often
runs from early December to early and mid January. Stage II is a period of rapid
fruit growth due to both cell division and enlargement that mainly involves the
growth and development of the endocarp (seed/pit). There is little development of
the flesh (mesocarp), nor is there significant oil production in the fruit at this time.
Lavee (1996) suggests that imposing moisture stress on the crop in the latter part of
stage two can reduce seed size and improve the flesh-pit ratio in table olives.
Where irrigation water is limited some water stress late in this period can also
reduce vegetative vigour and reduce competition for the developing crop. Moderate
moisture stress is not thought to impact on oil production potential. However,
stress, sufficient to limit cell division, has been reported to potentially limit
eventual fruit size and yield potential.
34
III. Seed/pit hardening (endocarp sclerification). Fruit growth slows during stage III as
the fruit undergoes a hardening of the endocarp. This process can last 4-5 weeks
running into early to mid February. There is little growth of the fruit and little oil
synthesis during this period. The crop can tolerate reasonable moisture stress
during this period and it is a time when fruit respiration is low. The tolerance of dry
conditions also applies to the vegetative parts of the tree and vegetative growth will
also slow or stop when stomata close up and transpiration slows in the hot
conditions of January to early February.
IV. Mesocarp (fruit flesh) development (cell enlargement oil synthesis). Beginning in
early February stage IV is the second period of rapid fruit growth. This growth is
due to development of the mesocarp or flesh of the fruit and mainly involves cell
enlargement. This is also the main period of oil synthesis with oil accumulation in
the fruit being directly correlated with fruit growth (dry matter increase) during this
period. Moisture stress can restrict growth of the fruit and oil production potential.
Lavee (1996) reports that where irrigation water is limiting the most benefit to
productivity is gained in this period. I observed in the field that as stage IV
progresses the fruit becomes increasingly susceptible to moisture stress and
desiccation, with the fruit appearing desiccated. This may be related to the
progressive increase in fruit respiration rate (Ranalli et al. 1998) and the increasing
mass of soft tissue in the fruit. Where irrigation water supply is limited it may be
possible to impose a moderate deficit at the beginning of this period and increase
water inputs as fruit growth progresses.
35 V. Ripening. Ripening commences with green maturation. This is described as the
change from dark lime green to lighter green but it can be determined more
accurately in the field by observing the onset of fruit softening. This rapid change
in fruit texture takes place over a period of one to two weeks and can be observed
as a change from hard (Granny Smith apple texture) where the fruit is difficult to
squash between thumb and index finger, to softer texture where the fruit is easily
squashed and milky juice is released. As the fruit ripens, dry matter continues to
increase along with oil synthesis, although at a slower rate than in stage IV. As
with stage III, the respiratory demand from the fruit lessens and with the weather
cooling, drops off. Crop water management in stage V can have a dramatic impact
on yield and quality characteristics. Fruit moisture content tends to drop off as
ripening commences and imposing a water deficit on the trees would be expected
to reduce fruit moisture further. It is possible that imposing water stress combined
with the onset of colder weather can reduce metabolic activity in the fruit leading
to reduced utilization and greater retention of phenolic compounds in the ripening
fruit. In addition low fruit moisture at oil extraction time may increase the
proportion of phenols in the oil due to reduced loss in vegetation water. Monitoring
fruit moisture levels in the ripening period can provide a useful guide to crop water
management to ensure that the required fruit moisture levels are attained at harvest
time. Varieties will vary substantially in their response to water deficits and
different irrigation management may be necessary for different varieties.
36 1.6 Summary
As many of the trees planted are now reaching production age, the next few years will see a sub stantial increase in olive oil production in Australia. Australian producers will need to:
• Produce consistently high quality olive oil; and
• Implement effective management practices to ensure cost efficiency.
This will allow Australian producers to compete on both the domestic and international markets.
1.7 Aims and objectives
1.7.1 Aims
There is very limited knowledge of the effect of the Australian environment on the quality of olive oil. This work aims to address two key issues of importance to the Australian olive industry:
• The influence of time of harvest on olive oil quality and stability; and
• The effect of different irrigation regimes on olive oil quality and stability.
1.7.2 Objectives
Objective 1
• To determine the optimal harvest time for olive oil quality and yield for three
cultivars through the measurement of oil quality components throughout the
fruit ripening period.
Objective 2
• To determine the effects of various irrigation treatments on olive ripening
behaviour and oil quality. 37 2 Chapter 2 Materials and methods
2.1 Wagga Wagga oil research laboratory
The analysis for this project was done at the Oil Research Laboratory (ORL),
New South Wales Department of Primary Industries, Wagga Wagga. The facilities at Wa gga encompass oil research, commercial oil analysis, education and organoleptic testing. The laboratory holds several accreditations including accreditation by the International Olive Oil Council (IOOC) to analyse olive oil for minor components as well as ISO 9002:1994 Quality Management Certification and
NATA (National Association of Testing Authorities) accreditation for several oil testing methods. The laboratory has held approved chemist status from the American
Oil Chemists’ Society for many years. The analytical methods used in this project are IOOC accredited methods, except where noted.
2.2 Grove site and trial plan
The site for this project was the Nugan Group Pty. Ltd. property
‘Cookathama’, a commercial olive grove situated at Darlington Point (latitude 34o
57`, longitude 146o0`), 33km south of Griffith in south-western New South Wales.
The ‘Cookathama’ olive orchard was planted in the period from 1997 to 2001. It is a modern young orchard containing approximately eighty thousand trees, the oldest of which have reached commercial production age. The layout, large scale of plantings and uniformity of field conditions were ideal for biometrical analysis of separate cultivars, unlike the majority of established olive groves in Australia.
The grove contains four main cultivars, Mission, Paragon, Corregiolla and
Leccino. Three of these - Mission, Paragon and Corregiolla were selected to be included in this study due to the grove layout and the differences between the
38 cultivars. Each of the three cultivars had been planted in individual blocks, and to aid pollination, every tenth row was planted to cv. Pendulino, which flowers early and abundantly, and has a lengthy flowering period. Trees were planted in a 5 metre by 8 metre rectangular grid pattern in rows 400 metres long. The trees used in the trial are located in a block of about 11 000 trees, planted in 1997-8.
The trial design was a randomized block with three replications (Figure 2.1).
Six rows of trees were included in each of three blocks identified as replicate 1, 2 and
3. The six rows included three treatments: full irrigation, partial irrigation and nil irrigation and a buffer row between each treatment.
F P N N F P P N F
Tree
no. Legend
F - Full irrigation 11-20 4 2 1 P - Partial irrigation
N - Nil irrigation 21-30 2 1 3
Rep. - Field replicate 31-40 1 3 4
41-50 3 4 2
Rep. 1 Rep. 2 Rep. 3
Figure 2.1 Harvest plan for each cultivar. Randomised block designs were used for each of the four harvests undertaken each year. Each line represents a row of eighty olive trees in the field.
39 2.3 Irrigation
The trial was located on a large area of medium to heavy self-mulching cracking grey clay loam soil. Prior to experimental design, the trial area was surveyed using an EM31 electromagnetic survey probe along with soil sampling and texturing. This measures conductivity or resistivity of different parts of the soil profile. As a result of the survey, the trial area was located to maximise uniformity of soil type and depth.
Irrigation was applied through furrows positioned approximately 1.5 metres outside of the tree line. The furrows and under tree area were maintained in a weed- free state through the use of herbicides while the inter-row area was planted to fescue and perennial rye grass. Irrigation water was applied by syphons with each watering event applying approximately 0.5 megalitres per hectare, the equivalent of 50 mm of rainfall. There was variability in the supply of water within each row due to variations in furrow depth and distance from the trees.
Irrigation treatments on olive orchards on Cookatharma were given lower priority for watering in the first two years of this study due to water limitations caused by drought. A further complication was the failure of the gypsum blocks, installed to monitor soil moisture. In year three of the project distinct irrigation treatments were applied, but again water availability for irrigation was restricted resulting in no irrigation being applied beyond mid March 2004. Irrigation was deficient during late fruit growth and oil synthesis and fruit maturation periods.
Three irrigation treatments were applied. The treatments were: high irrigation
(G), moderate deficit irrigation (Y) and severe deficit irrigation (R). The high irrigation regime received a total of six irrigations between November 2003 and Mid
March 2004, applying approximately 3 megalitres of water to the crop. At an irrigation efficiency of 80% this represents about 2.4 megalitres of plant available 40 water being applied. The moderate deficit treatment was watered 4 times while the severe deficit treatment was watered three times, supplying total water volumes of
1.6 and 1.2 Ml/ha respectively.
2.4 Soil moisture monitoring
Gypsum blocks: A total of 108 heavy soil gypsum blocks supplied by TAIN electronics were installed across the trial area. The blocks were located at 30, 60 and
90 cm depth at 1 metre and two metres distance from the base of selected trees in each treatment.
Neutron probes: Neutron probe tubes were installed in September – October
2003 and the soil water was monitored with a model 503 Hydroprobe on a weekly basis from October 2003 through to May 2004.
Neutron probe access tubes were located in one replication of each irrigation treatment of each variety. The tubes were installed 1.2 m from the base of the tree and 0.5 m from the centre of an irrigation furrow. The probe was calibrated at the time of tube installation and the calibration equation was applied to readings taken over the course of the irrigation period.
Readings were taken at depths of 10, 20, 30, 40, 50, 70, 90, 105 cm below the soil surface. This provided a detailed picture of water movement in the soil and the depth of penetration of soil moisture following irrigation or rainfall events. It also provided information on the zone of root activity in the soil from the varying rates of soil moisture depletion from different depths. Soil moisture depletion from various soil depths following irrigation was recorded.
41 2.5 Sample collection
Olives were harvested according to a statistical design (Figure 2.1). At each of four h arvests, a total of 3Kg f ruit was taken from ten trees within each of three replicates for each cultivar. Trees were harvested only once so as not to change natural conditions which may influence the next harvest.
In addition to the four main harvest dates, two initial “early” harvests of 300 g of fruit were carried out in mid to late February and mid to late March, to provide additional data on fruit size and weight, maturity index, moisture content and fatty acid profile.
Four harvests were carried out:
(1) prior to the normal commercial harvest window (early April),
(2) and (3) during the normal commercial harvest period (early to mid April
and late May) and
(4) post commercial harvest period (mid July) (Table 2.1).
Wagga Wagga laboratory staff travelled to the olive grove on the dates shown in Table 2.1 and sampled olives as described. Fruit were packed in calico bags and packed gently into plastic trays. They were transported back to Wagga on the same day and placed into cool rooms at 8oC until testing. Fruit was processed within four days after harvest. Examples of fruit from each cultivar and at each harvest were photographed for future reference, including external and internal fruit colour and kernel shape.
42 Analyses carried out on fruit from the harvests included:
maturity index chlorophyll content
moisture content peroxide value
fatty acid profile induction time
total polyphenol content α-tocopherols – 2004 only
free fatty acids fruit firmness – 2004 only
Table 2.1 Harvest dates for the years 2002, 200 3 and 2004. 2002 2003 2004
Harvest 1 28 February 17 February 18 February
Harvest 2 25 March 18 March 18 March
Harvest 3 8 April 7 April 13 April
Harvest 4 30 April 30 April 5 May
Harvest 5 23 May 28 May 31 May
Harvest 6 8 July 15 July 12 July
2.6 Maturity index
The maturity index was determined on 100 randomly selected olives in each sample to obtain a numerical value for the olive sample appearance. Olives were cut in hal f to expose the intern al flesh and to permit grading.
43 The olives were sorted into categories using the following parameters:
0 = skin is a deep or dark green colour.
1 = skin is a yellow or yellowish-green colour.
2 = skin is a yellowish colour with reddish spots.
3 = skin is a reddish or light violet colour.
4 = skin is black and the flesh is completely green.
5 = skin is black and the flesh is a violet colour halfway through.
6 = skin is black and the flesh is a violet colour almost through to the
stone.
7 = skin is black and the flesh is completely dark.
The total number of olives in each category was counted and recorded. The following equation was then applied to determine the maturity index:
Maturity Index = (0 x no) + (1 x n1)…+ (7 x n7)
100
where n is the number of fruit with that score (Boskou 1996).
44 MI 1
MI 2
MI 3
MI 4
MI 5/6
MI 7
Figure 2.2 Olive fruit at various stages of ripeness based on the maturity index (Paragon cultivar).
The appearance of the fruit over the maturation period is illustrated in Figure
2.2. The green skin will change gradually to become totally black. The internal
45 flesh will also change from bright green to a milkish white and eventually become purple to black. To determine maturity index, it is necessary to cut the fruit open to examine the colour of the flesh. The early change in skin colour compared to the relatively late change in flesh colour shown in Figure 2.2 illustrates the problems in predicting the maturity of the olive. The problem is further increased as the rate of change in both fruit skin colour and flesh colour may vary considerably between trees of one cultivar and even within a single tree.
2.7 Moisture and oil analysis
2.7.1 Moisture content
Approximately 1 Kg of fruit was crushed using a hammer mill. After mixing the sample thoroughly, approximately 30 g of paste was transferred to a previously weighed Petri dish. The sample was dried in a fan-forced oven at 80°C for 24 hours.
The sample was removed from the oven, placed in a desiccator and cooled to room temperature. The dry weight of the sample was recorded and the moisture content of the fruit calculated as a percentage of the fruit weight.
2.7.2 Oil content - cold press extraction
A cold press extraction unit, similar to that used in the IOOC accredited laboratory, Ministerio de Agricultura Pesca, Y Alimentacion, in Madrid, Spain, was purchased from Abencor, Spain. The Abencor unit imitates the process used by the industry to extract olive oil. It consists of three units: a hammer mill, a thermo- malaxer and a centrifuge (Figure 2.3).
Approximately 1 Kg of fruit was ground to a paste using the hammer mill.
The sample was thoroughly mixed and 700 g of the pulp was weighed into a mixing
46 jar. The jar was placed in the thermo-malaxer and allowed to stir for 20 minutes with the water bath set at 25°C. Following this, 300 mL of boiling water was added to the sample, and stirred for 10 minutes. The sample was then centrifuged for 1 minute.
After collecting the “oily must” in a measuring cylinder, the pomace was rinsed with
100 mL of boiling water, centrifuged for 1 minute, and the “must” again collected.
After allowing some time for the sample to settle, the quantity of oil was transferred to a vial, purged with nitrogen and stored until analysis.
47 (a)
(b)
(c)
Figure 2.3 Abencor (a) hammer mill, (b) malaxer and (c) centrifuge used to extract the oil
from olives. This is a Spanish system used to replicate industrial scale cold press extraction
of olive oil.
48 2.8 Olive Oil Quality note: all solvents used were AR grade and purchased from Lomb Scientific in
Sydney, unless otherwise stated.
2.8.1 Total polyphenol content
A modification of the Gutfinger (1981) method, using caffeic acid (Sigma
Aldrich, Sydney) as the standard, was used to determine total polyphenol content. Oil
(10 g) was dissolved in hexane (50 mL) (AR grade) (Lomb Scientific, Sydney) and extracted 3 times with 20 mL portions of 80% aqueous methanol. The mixture was shaken for 2 min for each extraction. The sample was made up to 100 mL with water and left to stand in a dark cupboard overnight. An aliquot (1 mL) was transferred to a
10 mL volumetric flask to which 5 mL of water was added. Folin-Ciocalteau reagent
(0.5 mL) was then added and the sample shaken and left for 3 minutes. Folin-
Ciocalteau reagent is a commercial reagent containing lithium sulphate (10-30%), sodium tungstate (1-10%), orthophosphoric acid (1-10%), sodium molybdate (1-
10%), hydrochloric acid (1-10%) and water. Saturated Na2CO3 (1 mL) was added and the sample shaken again. The sample was made up to volume with water and allowed to stand for 1 hour. The absorption was read at 725 nm using a Varian Cary
1 spectrophotometer. Solutions of caffeic acid were prepared and used to produce a standard calibration curve. The standards were prepared and analysed in the same way as the sample solutions.
2.8.2 Induction time
A Metrohm 679 Rancimat, a machine which accelerates the oxidation of oil, was utilised to determine the induction time of the oil. A block temperature of 130°C and airflow of 20 l/hour was used. Volatile components which develop as a result of 49 oxidation were measured by this process. When the oil begins to oxidise, the change in conductivity of the water used to trap these volatile components is recorded. These results were reported as induction time, in hours.
2.8.3 Fatty acid profile
Olive oil (100 mg) was mixed with petroleum spirit (3 mL b.p. 40-60°C) in a small test tube. Sodium methoxide (0.5 mL, 1.15% sodium in methanol solution was added, and mixed for 15 seconds. The sample was allowed to stand for 10 minutes and bromothymol blue (0.1 mL; 0.1% w/v in methanol) was added followed by hydrochloric acid (0.4 mL; 1M). Sodium carbonate (0.6 mL, 1.5%) was added and the solution mixed thoroughly. Distilled water (approx. 10 mL) was added to bring the solvent layer to the top of the test tube and allowed to stand for 5 minutes to allow phase separation. The solvent layer was transferred to GC vials. The fatty acid profile was determined by gas chromatography using a SGE BPX70 capillary column (30 m, 0.22 mm, 0.25 µm film) (SGE, Sydney Australia) and a flame ionisation detector. The column temperature program was 185°C for 8 minutes then increased at 10°C/minute to a final temperature of 220°C and held for 3 minutes.
Total run time was 13.5 minutes. The injector (split mode) temperature was set at
250°C with a split ratio of 1:50. Detector temperature was 260°C. Data was analysed using Star® Workstation Chromatography software (Version 6.20). The results were expressed as a percentage of the total fatty acids.
2.8.4 Free fatty acids
Free fatty acids were determined by a modified method of the American Oil
Chemists’ Society (Aa 6-38) (AOCS 1998). Olive oil (7.05 g) was dissolved in neutralised isopropanol (50 mL). Two drops of phenolphthalein (1% in ethanol) were
50 added to the solution. The sample was then titrated with 0.1M NaOH, previously standardised against HCl. The volume of titrant was recorded and the results calculated as a percentage FFA of the total oil (expressed as oleic acid).
2.8.5 Peroxide value
Peroxide value was determined using the International Union of Pure and
Applied Chemistry (IUPAC 1992) method 2-501. Olive oil (2.50 g) was dissolved in acetic acid/chloroform mixture (3:2). To this solution, 1mL of saturated KI (70 g KI in 40 mL water) was added, and shaken for 1 minute. The sample was then placed inside a dark cupboard for 5 minutes. Water (75 mL) was added, followed by two drops of starch solution (2.5 g starch/100mL water). The solution was titrated with previously standardised 0.01M sodium thiosulphate (Na2S2O3). The volume of titrant used was recorded and the peroxide value calculated and reported as mEq of active oxygen/Kg oil.
2.8.6 Chlorophyll
Chlorophyll was measured using the method of the American Oil Chemists’
Society, Ch 4-91 (AOCS 1998). The absorbance of the olive oil sample was measured on a Varian Cary 1 spectrophotmeter, using dichloromethane as a reference, at 630, 670 and 710 nm. The chlorophyll content was then calculated by subtracting the maximum absorbance (670 nm) from the other two measured absorbances (710 and 630 nm), and reported as mg chlorophyll/Kg oil.
2.8.7 α-Tocopherols
α-Tocopherols were analysed in 2004 only, to gain a further understanding of the effect of antioxidants on the stability of olive oil. Tocopherols were measured 51 using IUPAC method 2-432 (IUPAC 1992) with slight modification. Olive oil (2 g) was weighed into a 25 mL volumetric flask, and made to volume with hexane. The samples were filtered and transferred to HPLC vials. The α-tocopherol concentration was determined by HPLC (Waters), with hexane/isopropanol (99:1) (stated as
99.5/0.5 in IUPAC method) as solvent with a flow rate of 1 mL/min A Phenomonex
Luna 5µ Silica column (250 by 4.60 mm) was used. The peaks were measured using a UV detector set at 292 nm. Data were analysed using Waters Empower Pro® version 5.00.
52 3 Chapter 3 Results and discussion
3.1 Introduction
This is one of the first scientific studies of its type to relate harvest timing to olive oil quality and stability in Australia. The results provide growers with valuable information on how to achieve specific quality in their olives by targeting fruit maturity. As a result a grower may choose to produce pungent and peppery oil or a mellow to bland oil. The opportunity is there to select oils with increased shelf life stability when antioxidants are at a high level. The oil may be processed when it is green or left to become golden yellow. Even the level of polyunsaturated fatty acids can be influenced by monitoring fruit quality and selecting the optimum harvest date.
It is difficult to apply chemical tests to determine harvest timing as they are often expensive and time consuming. By the time chemical analysis has been carried out, the grower may have missed the optimum time for harvest. However, it is worthwhile to do some standard analysis so growers can gain a general idea of the quality of their oil This analysis is necessary to help growers relate physical testing to oil quality under their own conditions. Chemical testing is recommended for individual conditions, at least in the initial years of generating a crop.
The rate, evenness and time of ripening will vary between varieties, environments, seasons and management practices. Studies from Europe into management practises such as harvest timing are often highly specific in terms of location and local genotypes and therefore of limited use for broader interpretation and application (Giametta 1992, Rahmani et al. 1997, Tombesi 1990). This project conducted research on commonly grown cultivars in Australian conditions.
53 3.2 Climatic conditions and evapotranspiration
3.2.1 Climatic conditions
The trial was conducted during three years of severe drought in the Riverina.
Mean monthly maximum and minimum temperatures over the course of the project are shown in Figure 3.1. Total rainfall for the July to June periods over the course of the research was 288, 253 and 354 mm for 01/02, 02/03 and 03/04 respectively. The long term mean annual rainfall for the area is 395 mm. The rainfall and potential crop evapotranspiration ETp are shown in Figure 3.2, illustrating a high level of dependence on irrigation to supply crop water requirements. In 2004 this demand for irrigation was particularly high in the period from late December 2003 to late
May 2004. Availability of water for irrigation was a problem, as discussed in
Section 2.3.
3.2.2 Potential crop evapotranspiration
Potential crop evapotranspiration ETp for olives was calculated by multiplying reference crop evapotranspiration by crop coefficients (Kc) of 0.5 to
0.65 (Fernandez 1999). Given the trees used in this study are not full size and have a canopy area of approximately 40% of the orchard floor area this Kc was reduced by 33% based on the assumption that full canopy size would cover 60% of the orchard floor area. Reference crop evapotranspiration (ETo) data used to calculate
(ETp) were supplied by CSIRO in Griffith NSW, the closest weather monitoring station to the trial site.
54 40.0 Max temp 01/02 Max temp 02/03 35.0 Max temp 03/04
Min temp 01/02 30.0 Min temp 02/03 Min temp 03/04 25.0
20.0 Air temperature (°C)
15.0
10.0
5.0
0.0 Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
Figure 3.1 Mean monthly maximum and minimum air temperatures for 2001/02, 2002/03 &
2003/04.
160 Rain 02 140 Rain 03
120 Rain 04
ET 02 100 p
ETp 03 80 mm/ha ETp 04 60
40
20
0 Jul Aug Sept Oct Nov Dec Jan Feb Mar Apr May Jun
Figure 3.2 Rainfall and crop potential evapotranspiration (ETp) for 2001/02, 2002/03 &
2003/04.
55 3.3 Irrigation
3.3.1 Zone of root activity
Gypsum blocks: The blocks did not function satisfactorily. There were two principal reasons for this: firstly, the deficit treatments involved drying the soil to fairly extreme levels resulting in cracking and shrinkage which led to loss of soil-gypsum block contact. The blocks were often slow to re-wet and many ceased to work at all.
The second reason was that the root system of the trees was concentrated in the top
50 cm and blocks located at 60 cm depth were below most of the roots and the depth of water infiltration on an average irrigation event. Only in the event of substantial rainfall events or watering and rainfall combined was there sufficient prolonged wetting of the gypsum blocks at 60 cm for them to re-wet. The tendency of the soil is to shrink and crack when dry, rendering the gypsum blocks ineffective and their use was discontinued.
Neutron probes: Soil moisture depletion was most rapid in the top soil from surface to 30 cm due to evaporation and water extraction by plant roots (Figure 3.3a). At 40 cm depth soil moisture depletion is primarily by plant roots (Figure 3.3b) and shows rapid soil moisture depletion followed by a much slower rate of depletion as VSM
(volumetric soil moisture) approaches the limit of plant available water at about 0.2 m3/m3. Fluctuation in soil moisture at 50 cm depth was less due to limited infiltration of water and reduced root activity causing much slower depletion at this depth
(Figure 3.3c). By late in the season (March –April) VSM at 50 cm was maintained very close the lower limit of plant available water due to an extended crop water deficit period. At 70 cm soil moisture did not fluctuate (Figure 3.3d) indicating no
56 plant water uptake from this depth. Soil moisture depletion from the 0-50 cm zone was used to monitor crop water use.
(a) (b)
0.35 0.35
20 cm 40 cm 0.3 0.3
0.25 0.25
0.2 0.2 VSM (m3/m3 soil)
0.15 soil) (m3/m3 VSM 0.15
0.1 24/11/03 19/12/0315/01/04 19/02/04 18/03/04 23/04/04 0.1 date 24/11/03 19/12/03 15/01/04 19/0 2/04 18/03/04 23/04/04 date
(c) (d)
0.35 0.35
50 cm 70 cm 0.3 0.3
0.25 0.25
0.2 0.2 VSM (m3/m3 soil) (m3/m3 VSM 0.15 0.15 VSM (m3/m3 soil) (m3/m3 VSM
0.1 0.1 24/11/03 19/12/0315/01/04 19/02/04 18/03/04 23/04/04 24/11/03 19/12/03 15/01/04 19/02/04 18/03/04 23/04/04 date date
Figure 3.3 Volumetric soil moisture (VSM) readings from (a) 20 cm, (b) 40 cm, (c) 50 cm and
(d) 70 cm below the soil surface from November 2003 to May 2004.
3.3.2 Crop water inputs
Soil moisture monitoring data is presented in Figure 3.4 a, b, c. Soil moisture was measured some days after each irrigation or rainfall event because the orchard was inaccessible after irrigation or rainfall.
Soil moisture monitoring revealed rapid depletion of soil moisture following irrigation or rainfall. Following depletion of readily available soil moisture the rate of
57 soil water uptake by the crop decreased as extraction from the soil became more difficult. This is illustrated by a levelling out of the soil moisture curves (Figure 3.4 a, b and c).
In the high irrigation treatment a total of 6 irrigations were applied at intervals of 2-4 weeks apart (Figure 3.4a). The long intervals between watering meant that trees were subjected to soil saturation followed by readily available water declining to fairly severe soil moisture deficits within each pre-irrigation interval. In the case of the deficit treatments the rate of soil moisture depletion slowed substantially as soil moisture approached the limit of plant available water. These extended dry periods produced visible signs of moisture stress in the plants such as upward turning and rolling of the leaves, as well as fruit shrivelling. Fruit shrivelling became increasingly frequent as fruit grew larger during stage IV (Section 1.5.1)
(Figure 1.11) of fruit development. Shrivelling was observed in all treatments and across all varieties as they were subjected to a soil moisture deficits through late fruit growth and maturation. Sanchez Raya (1983) observed fruit respiration progressively increased and peaked during this period of fruit growth, which is consistent with my observations of increasing susceptibility to desiccation as stage IV progressed.
The nature of furrow irrigation, with long intervals between irrigations and the lack of precision in water application, means that it is less than ideal for research into precise water management options for olive growers. However, the furrow irrigation applied in this orchard in 2004 was an efficient method of water application due to the accurate management of the irrigation system and its application by Cookatharma management. The long rows (400 m) means there is minimal excess flow of water into drainage channels (which is recycled).
Infiltration of water after irrigation was to 40-50 cm depth and there was no wastage of water through deep infiltration beyond the root zone.
58
160 irrigation (a) 150 rainfall High 120 130 irrigation
110 80
90
40 70 soil moisture (0-50 cm) Irrigation & rainfall (mm) 50 0 16/10/03 5/12/03 24/01/04 14/03/04 3/05/04
(b) irrigation 150 rainfall 120 Moderate deficit 130
110 80
90 40 70 soil moisture (0-50 cm) rrigation & rainfallrrigation & (mm) 50 0 I 16/10/03 5/12/03 24/01/04 14/03/04 3/05/04
160 irrigation (c) 150 rainfall Severe deficit
130 120
110 80
90
40
soil moisture (0-50 cm) 70 Irrigation & rainfall (mm)
50 0 16/10/03 5/12/03 24/01/04 14/03/04 3/05/04
Figure 3.4 Rainfall and irrigation events and volumetric soil moisture levels in the top 50cm of soil for (a) high irrigation (G), (b) moderate deficit (Y) and (c) severe deficit irrigation (R),
October 2003 to May 2004.
Crop water inputs were not limiting during stage I (Section 1.5.1) in any of the treatments, hence all treatments received the same amount of irrigation. In stage II
(Figure 1.11) only 48%, 26% and 26% of potential crop water use was supplied to
59 the high, moderate deficit and severe deficit irrigation treatments respectively. In stage III (seed hardening) the deficit was 43% of ETp in high and moderate deficit irrigation treatments and 9% in the severe deficit irrigation treatment. In stage IV, the main period of oil synthesis the crop water supplied was 83%, 60% and 60% of crop potential water used, declining to 37% in all treatments in stage V (Table 3.1).
During late stage IV and stage V the fruit and trees showed signs of moisture stress with fruit shrivelling occurring in all treatments during this period.
Table 3.1 Crop water inputs in relation to potential crop evapotranspiration, ETp, at the different stages of fruit development - November 2003 to 12 May 2004.
Fruit ETp Development mm Crop water inputs (rainfall and irrigation) Stage High irrigation Moderate Severe deficit deficit irrigation Irrigation
mm % ETp mm % ETp Mm % ETp
I 74 97 100 97 100 97 100
II 137 66 48 26 19 26 19
III 117 50 43 50 43 10 9
IV 171 142 83 102 60 102 60
V 71 26 37 26 37 26 37
3.4 Maturity index
The maturity index is a mathematical measure of the degree of ripeness of the fruit which is commonly used in Europe (Shimon Lavee pers. comm.) to determine when to harvest fruit. The method uses a visual colour assessment of 100 randomly selected olives to obtain a numerical value of between 1 and 7. The proportions of
60 each category are then calculated as described by Boskou (1996). This method is useful where oil yield is the only consideration, but it does not provide an accurate guide where oil quality is an important consideration.
In this study, fruit changed colour over a period of 3-4 months (Figure 3.5a, b and c) with some cultivars showing a longer period to change from green to black than others. It clearly shows that over the three years, Mission continued to change colour in the skin and throughout the fruit until the final harvest, whereas
Corregiolla and Paragon tended to turn black but the flesh remained green to pale throughout maturation.
There was a significant year effect (p = 0.006) for the maturity index recorded for Corregiolla over three years, meaning the maturity index of this cultivar responded differently each year of the three years studied. The Mission and
Paragon cultivars did not show a significant year effect for maturity index, and there was no irrigation effect for any of the cultivars.
61
(a)
6 Corregiolla
4
2 Maturity index
2002 0 2003 2004
40 60 80 100 120 140 160 180 200 220 Days after January 1 (b)
6 Mission
4
2 Maturity Index
2002 0 2003 2004
40 60 80 100 120 140 160 180 200 220 (c) Days after January 1
6 Paragon
4
2 Maturity index
2002 0 2003 2004
40 60 80 100 120 140 160 180 200 220 Days after January 1 Figure 3.5 Maturity index for each of the cultivars studied (a) Corregiolla, (b) Mission and (c)
Paragon. As there was no irrigation effect, each point represents the mean of nine replicates
± standard error.
62
Maturity index continues to be used in Europe as a strong indicator of the optimum time to harvest (Shimon Lavee, pers comm.). In Australia however, the rate of change of maturity index for each cultivar was considerably different from that reported in Europe. For Corregiolla and Paragon in particular, if the colour had not changed by April, the flesh tended to remain green with a maximum maturity index of only 3-4 over the entire season. As a result, harvest timing relying on this parameter would result in very late harvest with markedly reduced quality. On the other hand, Mission showed a continual change in colour throughout the season until the flesh had become a rich purple. In this case, reliance on maturity may result in overripe fruit, from which it has been shown, oil quality is considerably reduced.
Oil extracted from green olives, or olives with black skins and green flesh generally exhibited grassy and pungent sensory characteristics whilst being processed, a characteristic preferred by consumers, whereas olives with a maturity index of 5 to 7 had lost this characteristic.
3.5 Moisture content
In Figures 3.6, 3.7 and 3.8, a comparison of time of harvest is shown for three cultivars for each of the three years of the study.
Corregiolla (Figure 3.6) showed a significant decline in moisture content over each of the periods of harvest for each of the three years (p < 0.001). Moisture content was not significantly different over the three years (p = 0.053) and there was no effect of irrigation on moisture content. This would suggest irrigation was insufficient.
63 Mission moisture concentration also declined, albeit slightly, for each harvest time over the three years (p = 0.019) although in 2002 there was very little change in moisture content throughout fruit growth (Figure 3.7). There was a significant difference between the three years (p < 0.001) but the lack of significant difference between irrigation treatments (p = 0.470) would suggest that irrigation was deficient.
Paragon (Figure 3.8) showed the greatest range in moisture content of the three cultivars although the year effect was not significant (p = 0.452). The constant decline in moisture content as the fruit matured in 2002, and to a lesser extent in
2003, was quite different to the variable moisture content observed in 2004. Despite that, the effect of harvest timing overall indicates that it is significant (p = 0.026).
There were no irrigation effects (p = 0.477).
Moisture content contributes more than 50% to the weight of an olive fruit. It therefore affects fruit and oil quality in several ways. Moisture content is very variable across the maturation period as the olive fruits take up water when it is abundant but will release moisture when it is in short supply. The appearance of the fruit changes as it becomes round and plump after an irrigation or rainfall event but it may become shrivelled and smaller with water stress.
Moisture content of the fruit is important to oil quality for a number of reasons. If the fruit moisture level drops to a point where desiccation occurs, cell breakdown can follow leading to increased free fatty acids and therefore lower oil quality. Stress conditions during mesocarp development (Stage IV, see Section1.5.1) may also result in reduced oil yields by limiting oil synthesis and accumulation.
Fruit growth may also be restricted. On the other hand, if the moisture content of the fruit is very high at the time of harvest, low yields result from cold press extractions.
Moisture levels at the time of harvest may also have effects on fruit quality which will in turn affect oil quality. The moisture content of the fruit can be influenced by
64 numerous factors including rainfall, evaporation, irrigation events, soil type and tree health.
In addition to the variability in moisture availability during maturation, there is a tendency for the fruit to retain less moisture as it matures. This study showed that moisture was generally high, around 50%, in all of the cultivars at fruit set and as the fruit began to develop. However, the moisture levels showed an overall downward trend across the season (Figures 3.6, 3.7 and 3.8). This was particularly evident in Paragon and Corregiolla. Mission however was very different to the other cultivars with moisture levels remaining relatively constant throughout fruit development.
There are no comparative statistical data between the three cultivars as the blocks were independent and there was no control between the blocks. The trends are similar for each of the cultivars with reductions in moisture content with maturity. In all cases this reduction was less for the third year.
In the prevailing drought conditions of the 2004 season, fruit moisture content changed in response to irrigation and rainfall events and the extremely dry conditions at this time. The fact that in premature fruit, moisture levels were at or below 50% in several of the varieties studied in late February gives an indication of the severity of soil moisture deficits imposed on the crop early in the season. There is a clear response to the mid March irrigation and the April 6 rainfall in all varieties and treatments. There was variation between cultivars in their response to soil moisture deficits with fruit moisture in Paragon (2004) responding to changes in soil moisture conditions much more dramatically than the other two varieties. In general, the fruit moisture levels illustrate that the crop experienced moisture deficit throughout late fruit growth, maturation and ripening. There was no significant effect of irrigation for any of the cultivars.
65
Moisture - Corregiolla
2002 60 2003 2004
50 % Moisture
40
30 40 60 80 100 120 140 160 180 200 220 Days after January 1
Figure 3.6 Moisture content for Corregiolla at six harvest dates over three years. There
was no effect between years (p = 0.053) and no irrigation effects (p = 0.986) although there
was significant time of harvest effects (p < 0.001). As there was no irrigation effect, each
point represents the mean of nine replicates ± standard error.
66 Moisture - Mission
2002 2003 60 2004
50 % Moisture
40
30 40 60 80 100 120 140 160 180 200 220 Days after January 1
Figure 3.7 Moisture content for Mission at six harvest dates over three years. There was a significant year effect (p < 0.001) but no effect for irrigation treatment (p = 0.470). There was a significant time of harvest effect (p = 0.019). As there was no irrigation effect, each point represents the mean of nine replicates ± standard error.
67 Moisture - Paragon
2002 2003 60 2004
50 % Moisture
40
30 40 60 80 100 120 140 160 180 200 220 Days after January 1
Figure 3.8 Moisture content for Paragon at six harvest dates over three years. There was no significant year effect (p = 0.452) and no effect for irrigation treatment (p = 0.477) although there was a time of harvest effect (p = 0.026). As there was no irrigation effect, each point represents the mean of nine replicates ± standard error.
68 3.6 Olive oil quality
3.6.1 Total polyphenol content
Polyphenols are perhaps the most important of the minor components in olive oil due to the powerful antioxidant effect they have on the oil and the resulting contribution to shelf life stability. Oil from early harvested olives are typically high in polyphenol content and this component has been shown to relate closely to oil stability (Mailer et al. 2002). The polyphenols also have been shown to be closely associated to the organoleptic characteristics of the oil, being largely responsible for pungency and bitterness attributes. Sensory analysis has shown that young oils are generally more pungent and bitter than oil from mature fruit and again this is related to the polyphenol content (Gutierrez et al. 1992b).
Polyphenols are a very broad range of chemicals clustered together under one term. Considerable research has been carried out on the individual members of this group but for the purpose of this study, the compounds were measured in one group as total polyphenol content.
Anecdotal evidence suggests total polyphenol levels above 200 mg/Kg are necessary to produce good quality EVOO (extra virgin olive oil). Levels above 400 mg/Kg may be too high for the average consumer, producing a pungent oil. Mostly, cultivars in this study maintained reasonable levels of polyphenol on average, even into late maturity. This is not always the case with some Australian oil producing very low levels, below 100 mg/Kg, as seen in Corregiolla and Paragon cultivars in
2002 (Figures 3.9a and 3.11a), resulting in very mellow oils.
The individual performance of the three cultivars is illustrated in Figures
3.9a, b, c, 3.10a, b, c and 3.11a, b, c. Generally, all cultivars showed similar trends, with lower levels of polyphenols in the first year, increasing to higher levels in subsequent years. 69
Corregiolla had low levels of total polyphenols in 2002 (Figure 3.9a), starting at less than 200 mg/Kg in young fruit and reducing to less than 100 mg/Kg as they matured. In 2003 the polyphenols ranged from 350 down to 150 mg/Kg (Figure
3.9b). However, in 2004, polyphenols started in young fruit at above 500-700 mg/Kg and even at full maturity, they contained more than 400 mg/Kg (Figure 3.9c).
Corregiolla had significant year effects over the three years (p < 0.001) and significant differences between time of harvest (p < 0.001). The irrigation effect was not significant over the three years (p = 0.184).
Mission also showed increased levels of total polyphenols over the three years. Again the concentrations started at a high level and decreased with maturity.
The final harvest of Mission produced only 100 mg/Kg in the first year (Figure
3.10a) but around 300 mg/Kg in the third year (Figure 3.10c). Again, the year effect was significant (p = 0.009) and there was a time of harvest effect (p = 0.010). There was again no irrigation effect (p = 0.787).
Paragon was quite different to the other two cultivars showing different effects for the three years. The first year concentrations remained almost constant over the year (Figure 3.11a). In 2003 (Figure 3.11b), the levels started high, around
500-600 mg/Kg, and decreased to around 200 mg/Kg over the season. In 2004 the levels started at a lower level, increased to a maximum at mid maturity and then decreased to levels slightly lower than the original concentration of the young olives
(Figure 3.11c). For this cultivar alone there was an irrigation effect (p < 0.001) with highest moisture treatments producing the lowest concentration of polyphenol. As for the other two cultivars, there was a year effect (p < 0.001) and a time of harvest effect (p < 0.001).
70 The reason why Paragon alone had an irrigation effect is not clear but it would seem that this cultivar is more sensitive to water availability/stress than the other cultivars. However, the moisture content of the fruit indicated that it had higher moisture in the early part of fruit development but decreased in line with the other cultivars toward maturity (Figure 3.8).
Total polyphenols Corregiolla 2002
1000
High irrigation Moderate deficit irrigation Severe deficit irrigation 800
600
400
200 Total polyphenols (mg/kg oil as caffeic acid) caffeic oil as (mg/kg polyphenols Total 0 80 100 120 140 160 180 200 Days after January 1
Figure 3.9a Polyphenol content of Corregiolla at four harvest dates in 2002 including three irrigation treatments (high, moderate deficit and severe deficit). Each point represents the mean of three replicates ± standard error.
71
Total polyphenols Corregiolla 2003
1000
High irrigation Moderate deficit irrigation 800 Severe deficit irrigation
600
400
200 Total polyphenols (mg/kg oil as caffeic acid) 0 80 100 120 140 160 180 200 220 Days after January 1
Figure 3.9b Polyphenol content of Corregiolla at four harvest dates in 2003 including three irrigation treatments (high, moderate deficit and severe deficit). Each point represents the mean of three replicates ± standard error.
72
Total polyphenols Corregiolla 2004
1000
800
600
400
200 High irrigation Moderate deficit irrigation Severe deficit irrigation Total polyphenols (mg/kg oil as caffeic acid) oil as caffeic (mg/kg polyphenols Total 0 80 100 120 140 160 180 200 Days after January 1
Figure 3.9c Polyphenol content of Corregiolla at four harvest dates in 2004 including three irrigation treatments (high, moderate deficit and severe deficit). Each point represents the mean of three replicates ± standard error. There was a significant effect between years (p <
73 0.001) but no irrigation effect (p = 0.184). There was a significant effect for harvest timing (p
< 0.001).
Total polyphenols Mission 2002
1000
High irrigation Moderate deficit irrigation Severe deficit irrigation 800
600
400
200 Total polyphenols (mg/kg oil as caffeic acid) oil as (mg/kg caffeic polyphenols Total 0 80 100 120 140 160 180 200 Days after January 1
Figure 3.10a Polyphenol content of Mission at four harvest dates in 2002 including three irrigation treatments (high, moderate deficit and severe deficit). Each point represents the mean of three replicates ± standard error.
74
Total polyphenols Mission 2003
1000
High irrigation Moderate deficit irrigation 800 Severe deficit irrigation
600
400
200 Total polyphenols (mg/kg oil as caffeic acid) oil as (mg/kg caffeic polyphenols Total 0 80 100 120 140 160 180 200 220 Days after January 1
Figure 3.10b Polyphenol content of Mission at four harvest dates in 2003 including three irrigation treatments (high, moderate deficit and severe deficit). Each point represents the mean of three replicates ± standard error.
75
Total polyphenols Mission 2004
1000
High irrigation Moderate deficit irrigation Severe deficit irrigation 800
600
400
200 Total polyphenols (mg/kg oil as caffeic acid) 0 80 100 120 140 160 180 200 Days after January 1
Figure 3.10c Polyphenol content of Mission at four harvest dates in 2004 including three irrigation treatments (high, moderate deficit and severe deficit). Each point represents the mean of three replicates ± standard error. There was a significant effect between years (p <
0.001) but no irrigation effect (p = 0.787). There was an effect for harvest timing (p = 0.010).
76
Total polyphenols Paragon 2002
1000
High irrigation Moderate deficit irrigation 800 Severe deficit irrigation
600
400
200 Total polyphenols (mg/kg oil as caffeic acid) 0 80 100 120 140 160 180 200 Days after January 1
Figure 3.11a Polyphenol content of Paragon at four harvest dates in 2002 including three irrigation treatments (high, moderate deficit and severe deficit). Each point represents the mean of three replicates ± standard error.
77
Total polyphenols Paragon 2003
1000
High irrigation Moderate deficit irrigation Severe deficit irrigation 800
600 oil as caffeic acid)
400
200 Total polyphenols (mg/kg 0 80 100 120 140 160 180 200 220 Days after January 1
Figure 3.11b Polyphenol content of Paragon at four harvest dates in 2003 including three
irrigation treatments (high, moderate deficit and severe deficit). Each point represents the
mean of three replicates ± standard error.
78
Total polyphenols Paragon 2004
1000
800
600
400
200 High irrigation Moderate deficit irrigation Severe deficit irrigation Total polyphenols (mg/kg oil as caffeic acid) as caffeic oil (mg/kg polyphenols Total 0 80 100 120 140 160 180 200 Days after January 1
Figure 3.11c Polyphenol content of Paragon at four harvest dates in 2004 including three irrigation treatments (high, moderate deficit and severe deficit). Each point represents the mean of three replicates ± standard error. There was a significant effect between years (p < 0.001) and an irrigation effect (p < 0.001). There was also an effect for harvest timing (p < 0.001).
79 An interesting observation over three years was that each year, all cultivars showed an increase in polyphenol content overall. There are several possible reasons for this. Firstly, tree age could have had an influence.
• In 2002, the trees were 4-5 years of age, they had vigorous vegetative
growth and variable yields from tree to tree, typical behaviour for young
trees. Vegetative growth provides a dominant sink for nutrients in young
trees and this will have had an influence on fruit development and growth. It
is possible that this has contributed to lower than expected polyphenol levels
in all varieties in 2002.
• In year 2003 polyphenol levels were similar to those observed in industry,
starting high and reducing in all varieties as ripening progressed.
• In 2004 polyphenols levels were unusually high in all varieties. The trees at
this time were well established and producing good yields.
Moisture stress on the developing and ripening crop is also a likely cause for increased polyphenols. Fruit moisture was 45-50% on 18 February 2004 indicating a degree of moisture stress in the developing crop which would normally have fruit moisture levels of 55-60% under stress free conditions (Mailer and Ayton, unpublished data). Long intervals between irrigation events meant that the crop was subjected to periodic moisture stress throughout the season and the moisture deficit was almost continuous from mid March onwards, (see Section 3.3.3 Crop water inputs) leading to almost continuous moisture stress in late fruit development, maturation and ripening. The imposition of moisture deficits on the crop is the predominant reason for the very high polyphenol levels in all varieties in 2004 and this is consistent with the observations of other researchers (Tovar et al. 2002), who observed higher polyphenols in crops subjected to irrigation deficits.
80 In 2004 there were effects associated with the deficit irrigation treatments on polyphenol levels in Paragon but not Mission or Corregiolla. This is interesting in that Paragon is a variety that appears to respond dramatically to changes in soil moisture status with more dramatic fluctuations in fruit moisture content than
Corregiolla or Mission. Paragon was also the first variety to show foliar signs of moisture stress in the field, such as curling and yellowing of the leaves.
In this study the main period of prolonged moisture deficit common to all treatments was in late fruit development, maturation and ripening due to the cessation of irrigation in early March. It must be assumed therefore that part of the reason for a dramatic elevation in polyphenol levels in 2004 (compared to 2002 and
2003) across all treatments and varieties was because of a physiological response in the fruit to soil moisture deficits in late stage IV and throughout stage V of fruit development. The additional increase in polyphenol levels in the Paragon deficit treatments was most likely due to multiple causes. Polyphenols are concentrated in and near the skin of fruits and the surface area of skin per kilogram of fruit is greater when fruit size is smaller. The use of RDI (regulated deficit irrigation) in wine grapes is based on the idea of producing smaller berries which have higher levels of polyphenol per kilogram of fruit and more intense flavours (Parr and Bolwell 2000).
This is also a possible reason for the increase in polyphenol levels in the all of the treatments in Paragon and other cultivars where moisture availability was limiting.
Further work needs to be done to define and quantify the effects of deficit irrigation on polyphenol levels and other quality characteristics of olive oil. Many producers entering the market want olive oils that are not too bitter or pungent, so being able to prevent elevated polyphenol levels or reduce polyphenol levels will be just as important as being able to elevate polyphenol levels where robust oil characteristics and high stability are required. The stage or stages of fruit
81 development where crop water management will influence polyphenols synthesis is of great interest to olive oil producers. Understanding this could allow growers to exert control over the polyphenol levels in their olive oil.
3.6.2 Induction time
Induction time, as described in Section 1.3.3, is an accelerated oxidation method commonly used to indicate the relative stability of oil in storage. If the oil is stable, it will resist oxidation and result in a long induction time. However, unstable oils will have relatively short induction times. Although induction time in hours cannot be used to precisely represent a particular shelf or storage life it is useful for comparing oils to determine relative stability. The conditions under which the oil is stored will have a major influence on the storage ability. Induction time merely indicates the stability of oil in relation to others when stored under similar conditions.
Induction time was significantly different ( p < 0.002) for each of the cultivars for each of the three years as can be seen from Figures 3.12 a, b, c, 3.13a, b,c and 3.14a,b,c.
As for polyphenol content (Section 3.6.1), Paragon and Corregiolla had very short induction times in 2002 which became progressively longer over the three years. Induction time for Mission also increased over the three seasons, but not to the same extent. All cultivars showed significant differences between years (Tables
6.1, 6.2 and 6.3). There was again a strong effect of irrigation on Paragon but this was not apparent for the other two cultivars. The effect of harvest timing was less obvious for Mission than for the other two cultivars.
82 Induction time Corregiolla 2002
12 High irrigation Moderate deficit irrigation Severe deficit irrigation 10
8
6
4 Induction time (hours)
2
0 80 100 120 140 160 180 200 Days after January 1
Figure 3.12a Induction time of Corregiolla olive oil at four harvest dates in 2002 including three irrigation treatments (high, moderate deficit and severe deficit. Each point represents the mean of three replicates ± standard error.
83 Induction time Corregiolla 2003
12 High irrigation Moderate deficit irrigation Severe deficit irrigation 10
8
6
4 Induction time (hours)
2
0 80 100 120 140 160 180 200 220 Days after January 1
Figure 3.12b Induction time of Corregiolla olive oil at four harvest dates in 2003 including
three irrigation treatments (high, moderate deficit and severe deficit. Each point represents
the mean of three replicates ± standard error.
84 Induction time Corregiolla 2004
12
10
8
6
4 Induction time (hours)
High irrigation 2 Moderate deficit irrigation Severe deficit irrigation
0 80 100 120 140 160 180 200 Days after January 1
Figure 3.12c Induction time of Corregiolla olive oil at four harvest dates in 2004 including three irrigation treatments (high, moderate deficit and severe deficit. Each point represents the mean of three replicates ± standard error. There was a significant effect between years
(p < 0.001) and no irrigation effect (p = 0.417). There was also an effect for harvest timing (p
= 0.002).
85 Induction time Mission 2002
12 High irrigation Moderate deficit irrigation Severe deficit irrigation 10
8
6
4 Induction time (hours) Induction
2
0 80 100 120 140 160 180 200 Days after January 1
Figure 3.13a Induction time of Mission olive oil at four harvest dates in 2002 including three
irrigation treatments (high, moderate deficit and severe deficit. Each point represents the
mean of three replicates ± standard error.
86 Induction time Mission 2003
12 High irrigation Moderate deficit irrigation Severe deficit irrigation 10
8
6
4 Induction time (hours)
2
0 80 100 120 140 160 180 200 220 Days after January 1
Figure 3.13b Induction time of Mission olive oil at four harvest dates in 2003 including three
irrigation treatments (high, moderate deficit and severe deficit. Each point represents the
mean of three replicates ± standard error.
87 Induction time Mission 2004
12
10
8
6
4 Induction time (hours)
High irrigation 2 Moderate deficit irrigation Severe deficit irrigation
0 80 100 120 140 160 180 200 Days after January 1
Figure 3.13c Induction time of Mission olive oil at four harvest dates in 2004 including three
irrigation treatments (high, moderate deficit and severe deficit. Each point represents the
mean of three replicates ± standard error. There was a significant effect between years (p =
0.002) and no irrigation effect (p = 0.462). There was also an effect for harvest timing (p =
0.043)
88 Induction time Paragon 2002
12 High irrigation Moderate deficit irrigation Severe deficit irrigation 10
8
6
4 Induction(hours) time
2
0 80 100 120 140 160 180 200 Days after January 1
Figure 3.14a Induction time of Mission olive oil at four harvest dates in 2002 including three
irrigation treatments (high, moderate deficit and severe deficit. Each point represents the
mean of three replicates ± standard error.
89 Induction time Paragon 2003
12 High irrigation Moderate deficit irrigation Severe deficit irrigation 10
8
6
4 Induction time (hours) Induction
2
0 80 100 120 140 160 180 200 220 Days after January 1
Figure 3.14b Induction time of Mission olive oil at four harvest dates in 2003 including three irrigation treatments (high, moderate deficit and severe deficit. Each point represents the mean of three replicates ± standard error.
90 Induction time - Paragon 2004
12
10
8
6
4 Induction time(hours)
High irrigation 2 Moderate deficit irrigation Severe deficit irrigation
0 80 100 120 140 160 180 200 Days after January 1
Figure 3.14c Induction time of Mission olive oil at four harvest dates in 2004 including three
irrigation treatments (high, moderate deficit and severe deficit. Each point represents the
mean of three replicates ± standard error. There was a significant effect between years (p <
0.001) and an irrigation effect (p < 0.001). There was also an effect for harvest timing (p <
0.001).
91 Corregiolla showed a similar pattern across the years for induction time as it did for polyphenols. In 2002 induction time was virtually unchanged as the fruit matured
(Figure 3.12a). Induction time in 2003 showed a slight decline across the season
(Figure 3.12b). In 2004 the induction time was higher than the other years, ranging from about 11-12 hours at the beginning of the season to 10 or 11 hours at the end of the season (Figure 3.12c). There was a significant year effect (p < 0.001) and harvest timing effect (p=0.002). There was no irrigation effect (p = 0.417)
Mission showed similar results to Corregiolla, that is higher induction time as the years progressed. However Mission showed more of a decline across the season in each year (Figures 3.13a, b, c). There was a significant year effect (p = 0.002) and harvest timing effect (p = 0.043), but no irrigation effect (p = 0.462)
As for polyphenols, Paragon was the only cultivar which had a significant effect for irrigation (p < 0.001). The high irrigation treatment in particular had the lowest induction time which gives support to the hypothesis that higher irrigation produces lower polyphenols and less oil stability. There were significant effects shown for year (p < 0.001) and harvest timing (p < 0.001) (Figures 3.14a, b, c).
The increased induction time with the age of the trees is also important and also relates to increased polyphenols with tree age. As previously suggested, this is possibly the result of better tree and root establishment with better access to soil nutrients.
Other oil characteristics which may contribute to increased induction time include the ratio of saturated to polyunsaturated fatty acids, the level of other antioxidants such as the tocopherols, the amount of peroxide already present in the oil and the chlorophyll concentration. However, the relationships observed here suggest that polyphenol content has a large antioxidant effect. It also indicates that
92 total polyphenols provide a good picture of the oil stability without the need for expensive and time consuming analysis of individual polyphenol compounds.
When induction time of all cultivars was plotted against polyphenol content in our study there was a strong relationship, indicating the role that polyphenols play in oil stability. The relationship was even stronger when individual cultivars were analysed separately, with high regression coefficients observed (from 0.864 to 0.947) between total polyphenol content and induction time (Figure 3.15). These findings are very similar to the observations of Salvador et al. (2001), who found regression coefficients of between 0.873 and 0.964 when plotting total polyphenols against induction time for individual cultivars. This result would suggest that the relationship of ease of oxidation, or induction time, to polyphenols content is different for each cultivar. It is likely that different polyphenol profiles in each cultivar have different antioxidant effects. This has not been studied here but it would be of great interest to determine which polyphenol compounds provide the greatest level of stability.
Induction time was found to relate to many other components, particularly the individual fatty acids (Figures 6.1 and 6.2). It is also apparent that these parameters relate to polyphenol content. These findings indicate that there is considerable interrelationship between olive oil components which are so far unknown. This study has identified some of these factors which will lead to further research.
93 14 Corregiolla 12 ) 10
8
6 y = 0.0144x + 1.3593 4 R2 = 0.8643 Induction time(hours
2
0
14 Paragon 12 ) 10
8
6
y = 0.0136x + 1.3637 4 2 Induction time(hours R = 0.897 2
0
14 Mission 12 ) 10
8
6
4 0.6883 Induction time (hours y = 0.1097x 2 R2 = 0.9468
0 0 200 400 600 800 1000 Total polyphenols (mg caffeic acid/kg oil)
Figure 3.15 Relationship between induction time and polyphenol content in three cultivars of olives.
94
3.6.3 Fatty acid profile
Fatty acid analysis at various stages of maturity indicated that proportions of individual fatty acids vary considerably during fruit development. This is of significant importance to olive oil producers in selecting oil with good stability and a superior nutritional fatty acid profile (Wahrburg et al. 2002). Olive oil is considered to be highly nutritional oil due in part to the high level of monounsaturated oleic acid. Australian oils however vary considerably in their fatty acid profile and sometimes do not meet the international standards (Mailer 2005).
Palmitic acid: Palmitic acid (C16:0) is a saturated fatty acid which is commonly abundant in palm oil but also present in olive oil. As can be seen by Table 3.2, the percentage of palmitic acid decreased relative to the other fatty acids over time from around 16% to more nutritionally acceptable levels of 10%. Other researchers have also shown that palmitic acid decreases as with maturity of olives (Grati-Kammoun et al. 1999; Koutsaftakis et al. 2000). Even at these levels, olive oil contains relatively high levels of saturated fat compared to seed oils such as canola, which contains 3-5% saturated fat (Mailer 2005). This is important to consider in future research and possible selection of cultivars of olives with a lower level of saturated fat. Although the levels of palmitic acid were similar between cultivars at the first harvest, Mission consistently had a slightly lower level than Paragon and Corregiolla at the final harvest. The highest level of palmitic acid was in Paragon at 16.5 ± 0.1% on 17/02/03. Mission was the lowest at 10.4 ± 0.1% on 15/7/03 and 12/7/04 (Table
3.2).
95 There was a significant year effect (p < 0.001) on palmitic acid content for all cultivars. There were also significant effects of harvest timing (p < 0.001) in all cultivars but no effect of irrigation.
Oleic acid: The percentage of oleic acid (C18:1) was relatively consistent in 2003 and 2004 across all of the harvest times for all cultivars; there was virtually no change from early to late maturity. However, in all cases the oleic acid content decreased from early to late maturity in 2002 (Table 3.2). It is not clear why this occurred. The maximum concentration was in Corregiolla on 13/4/2004 at 73.5 ± 0.5
%. The minimum level was in Corregiolla at 62.1 ± 0.5 % on 23/5/02. Corregiolla and Paragon had significant year effects (p < 0.001) but there were no effects for harvest timing or irrigation. Mission did not have any significant effects for year, harvest timing or irrigation.
Linoleic acid: The percentage of linoleic acid (C18:2) increased as palmitic acid decreased resulting in the oil becoming more polyunsaturated over time (Table 3.2).
Linoleic acid content of Corregiolla reached a maximum of 17.8 ± 0.7 % on 23/5/02 while for Mission there was a minimum level of 6.4 ± 0. % in 28/2/02. All cultivars increased in linoleic acid content as they matured. The rate of accumulation was similar until late April when Corregiolla and Paragon slowed in comparison to
Mission. Corregiolla and Paragon had significant year effects (p < 0.001) although
Mission did not. Corregiolla and Mission had significant time of harvest effects (p <
0.001) but there were no irrigation effects.
96 Table 3.2 The percentage of Palmitic, oleic and linoleic acid of three olive cultivars over three years. Results are average of nine replicates ± standard error.
Corregiolla Mission Paragon Days after Harvest Jan 1 Date C16:0 C18:1 C18:2 C16:0 C18:1 C18:2 C16:0 C18:1 C18:2
Palmitic Oleic Linoleic Palmitic Oleic Linoleic Palmitic Oleic Linoleic acid (%) acid (%) acid (%) acid (%) acid (%) acid (%) acid (%) acid (%) acid (%)
59 28/2/02 14.8 ± 0.2 73.0 ± 0.3 7.5 ± 0.2 15.1 ± 0.1 73.1 ± 0.2 6.4 ± 0.1 15.2 ± 0.1 72.3 ± 0.2 7.6 ± 0.2 84 25/3/02 15.5 ± 0.2 67.8 ± 0.3 12.1± 0.2 15.4 ± 0.1 69.4 ± 0.2 10.2 ± 0.1 16.0 ± 0.1 67.6 ± 0.3 11.8 ± 0.3 98 8/4/02 15.4 ± 0.2 66.5 ± 0.3 13.2 ± 0.1 14.6 ± 0.2 69.3 ± 0.5 11.3 ± 0.3 15.6 ± 0.1 67.2 ± 0.3 12.4 ± 0.3 120 30/4/02 14.5 ± 0.1 64.4 ± 0.3 15.7 ± 0.2 13.2 ± 0.2 68.8 ± 0.3 13.2 ± 0.2 14.5 ± 0.1 65.5 ± 0.4 14.8 ± 0.3 143 23/5/02 14.2 ± 0.2 62.1 ± 0.9 17.8 ± 0.7 12.2 ± 0.1 67.6 ± 0.7 15.1 ± 0.4 14.0 ± 0.2 64.9 ± 0.6 15.5 ± 0.4 189 8/7/02 14.0 ± 0.1 62.8 ± 0.5 17.5 ± 0.4 12.1 ± 0.2 67.4 ± 0.7 15.4 ± 0.5 14.2 ± 0.1 64.8± 0.5 15.6 ± 0.4
48 17/2/03 16.3 ± 0.1 69.6 ± 0.3 8.5 ± 0.1 16.2 ± 0.0 69.9 ± 0.1 7.5 ± 0.1 16.5 ± 0.1 69.5 ± 0.2 8.3 ± 0.2 77 18/3/03 15.6 ± 0.1 69.5 ± 0.5 10.2 ± 0.4 14.9 ± 0.1 70.4 ± 0.1 9.3 ± 0.1 15.4 ± 0.1 69.8 ± 0.2 10.0 ± 0.2 97 7/4/03 14.5 ± 0.2 69.2 ± 0.3 11.4 ± 0.2 13.2 ± 0.1 70.5 ± 0.3 10.7 ± 0.3 14.7 ± 0.2 69.6 ± 0.5 10.7 ± 0.3 120 30/4/03 14.4 ± 0.2 68.8 ± 0.4 11.9 ± 0.3 12.3 ± 0.1 71.3 ± 0.2 11.4 ± 0.2 14.8 ± 0.1 68.0 ± 0.4 12.1 ± 0.3 148 28/5/03 13.8 ± 0.2 68.9 ± 0.5 12.3 ± 0.4 11.2 ± 0.1 71.6 ± 0.2 12.2 ± 0.2 14.1 ± 0.3 68.4 ± 0.5 12.3 ± 0.3 196 15/7/03 12.4 ± 0.1 71.1 ± 0.4 11.8 ± 0.2 10.4 ± 0.1 71.3 ± 0.3 13.5 ± 0.2 13.0 ± 0.2 69.9 ± 0.2 12.1 ± 0.2
49 18/2/04 14.7 ± 0.2 72.8 ± 0.6 6.8 ± 0.3 15.4 ± 0.1 71.1 ± 0.4 6.9 ± 0.2 14.4 ± 0.1 71.4 ± 0.4 7.4 ± 0.1 78 18/3/04 14.4 ± 0.5 71.0 ± 1.1 8.5 ± 0.4 14.1 ± 0.3 69.5 ± 0.8 9.6 ± 0.5 14.2 ± 0.2 72.1 ± 0.3 7.6 ± 0.2 104 13/4/04 13.4 ± 0.1 73.5 ± 0.5 8.2 ± 0.3 12.7 ± 0.1 71.0 ± 0.4 10.4 ± 0.3 13.5 ± 0.1 73.2 ± 0.2 8.1 ± 0.1 126 5/5/04 13.3 ± 0.1 72.4 ± 0.3 9.5 ± 0.2 11.9 ± 0.1 71.0 ± 0.4 11.6 ± 0.3 13.5 ± 0.1 72.2 ± 0.2 9.1 ± 0.2 152 31/5/04 12.9 ± 0.1 72.1 ± 0.4 10.1 ± 0.3 11.2 ± 0.2 70.0 ± 0.5 13.3 ± 0.4 13.1 ± 0.1 72.4 ± 0.2 9.3 ± 0.1 194 12/7/04 11.9 ± 0.2 72.2 ± 1.1 10.9 ± 0.8 10.4 ± 0.1 70.4 ± 0.5 13.8 ± 0.3 12.1 ± 0.1 72.5 ± 0.3 10.0 ± 0.2
Linolenic acid (C18:3): Olive oil must conform to international standards and
Australian oil sometimes is outside of those requirements. In particular, linolenic acid sometimes exceeds the maximum standard of 1.0% (Mailer 2005). This can occur more often in immature oil as the linolenic acid level decreases as the fruit matures. Linolenic acid was found to be very high early in the season but decreased to acceptable levels (IOOC Standard <1.0%) by the beginning of April. All cultivars showed the same trend with Mission having a slightly higher level than the other cultivars at the last harvest. Linolenic acid in all three cultivars showed a tendency to increase slightly from mid June onwards.
Shelf life and oil stability are closely related to the degree of saturation and polyunsaturation of oils. The traditional fatty acid profile of olive oil produces a relatively stable product. Oleic acid is monounsaturated and therefore is relatively stable as it only has one reactive double bond per molecule. However, linoleic and linolenic acids, despite their perceived nutritional benefits, are both susceptible to oxidation as they are polyunsaturated (with two and three double bonds per molecule respectively).
(a) 3
Corregiolla 2002 2003 2004
2
1 Linolenic acidof (as total % fatty acids)
0 (b) 3 Mission 2002 2003 2004
2
1 Linolenicacid total (% of fatty acids)
0 (c) 3 Paragon 2002 2003 2004
2
1 Linolenic acidtotal (% of acids) fatty
0 40 60 80 100 120 140 160 180 200 220 Days after January 1
Figure 3.16 Linolenic acid for three cultivars (a) Corregiolla, (b) Mission and (c) Paragon
,over three years. Each point represents the mean of nine replicates ± standard error.
99
Generally there were some year effects for linolenic acid but no irrigation effects. Time of harvesting was important for Paragon and Mission but not for
Corregiolla.
Researchers have found that in olive oil oleic acid becomes higher and linoleic acid becomes lower as the climate where the olive trees are grown becomes cooler (Kiritsakis 1998). This has also been observed in Australia by researchers at the Oils Research Laboratory in Wagga Wagga (Ayton, J and Mailer, R., unpublished data), where the oleic acid content of oils from olives grown in
Tasmania was much higher than those grown in Queensland. This is an important observation as growers need to consider that cultivars grown in different latitudes and climates will produce oil with different fatty acid profiles (Mousa et al. 1996).
3.6.4 Free fatty acids (FFA)
Free fatty acids were generally very low in immature fruit. The levels remained low until May and the fruit had reached a high maturity index. At that stage Paragon showed a rapid increase in free fatty acids as the fruit aged (Figure
3.17b). In 2002 the free fatty acids in Paragon had exceeded the IOOC standard of
0.8% while the fruit were still on the tree. In 2004 the free fatty acid content in
Paragon remained steady throughout the season, at about 2%. Corregiolla showed an increase in free fatty acids in 2002 and 2003 (Figure 3.17a) as the fruit matured but not to the same extent as Paragon. The free fatty acid content of Corregiolla in 2004 remained relatively stable throughout the season in 2004 Free fatty acid content in
Mission increased slightly as fruit matured in 2002, but remained low throughout the harvest period in 2003 and 2004 (Figure 3.17b).
100 (a)
1.0 2002 Corregiolla 2003 2004
0.5 %FFA (as oleic acid) oleic (as %FFA
0.0 (b)
1.0 2002 Mission 2003 2004
0.5 %FFA (as oleis acid) (as oleis %FFA
0.0
(c)
1.0 2002 Paragon 2003 2004
0.5 %FFA (as oleic acid) oleic (as %FFA
0.0 80 100 120 140 160 180 200 220 Days after January 1 Figure 3.17 Free fatty acid (FFA) content for three cultivars (a) Corregiolla, (b) Mission and
(c) Paragon ,over three years. Each point represents the mean of nine replicates ± standard error. 101 The factors that contribute to an increase in free fatty acids are those that bring the triacylglycerols into contact with endogenous lipase enzymes which can break the molecules down. For example, as the fruit ages, free fatty acids increase with the rupture of cell walls. Other contributions may be due to reduction in moisture content to a level where desiccation caused cell breakdown and an increase in free fatty acids (Boskou 1996).
El Antari et al. (2000) found that higher acidity was chiefly caused by the harvest method applied. Acidity values of 0.5% or above could also be explained by poor fruit status prior to processing, poor crop health (ie. disease and pest infestation) or time of harvest. Grati-Kammoun et al. (1999) showed that the characteristics of oil changes with maturity and in particular the acidity increases with maturity, similar to the results found in this study, especially for the Corregiolla and Paragon cultivars.
3.6.5 Peroxide value
Peroxide values (see Section 1.3.2) were included in the analysis for the years 2003 and 2004 although little change was expected. Peroxides mostly form with oxidation, after the oil is extracted and exposed to air and therefore should not change significantly in the fruit. Peroxide value was shown to be higher in young olives than later in the season, especially in 2004 (Table 3.3) similar to the results found by Gutierrez et al. (1999) and Salvador et al. (2001), due to the decrease in lipoxygenase activity in the oil (see Section 1.4.5).
Peroxide value was influenced by years (p = 0.010 to < 0.001) but not by irrigation or time of harvest. All cultivars remained well under the International
Olive Oil Council’s standard of 20 mEq oxygen/Kg oil. Peroxide value is an indicator of the extent of oxidation that has occurred with a lipid. The oil oxidises more during and after processing than at any time before harvest. Factors which
102 affect oxidation rates of oil include exposure to air and light, temperature fluctuations during storage, the presence of free fatty acids and prooxidants such as chlorophyll,
water and microbial, metal ion and sediment content (Braverman 1976).
Table 3.3 Peroxide value at four harvest dates for three cultivars over two years. Results are an average of nine replicates ± standard error. Days after January 1 Harvest Date Peroxide Value
Corregiolla mEq oxygen/Kg oil 97 7/4/03 8 ± 0.4 120 30/4/03 7 ± 0.3 148 28/5/03 8 ± 0.3 196 15/7/03 9 ± 0.3
104 13/4/04 7 ± 0.4 126 5/5/04 8 ± 0.9 152 31/5/04 4 ± 0.5 194 12/7/04 5 ± 0.4 Mission 97 7/4/03 5 ± 0.3 120 30/4/03 7 ± 0.7 148 28/5/03 5 ± 0.3 196 15/7/03 6 ± 0.3
104 13/4/04 6 ± 0.5 126 5/5/04 6 ± 0.5 152 31/5/04 3 ± 0.2 194 12/7/04 2 ± 0.1 Paragon 97 7/4/03 9 ± 0.7 120 30/4/03 9 ± 1.0 148 28/5/03 9 ± 0.9 196 15/7/03 8 ± 1.0
104 13/4/04 7 ± 0.5 126 5/5/04 8 ± 0.8 152 31/5/04 4 ± 0.2 194 12/7/04 5 ± 0.3
103 3.6.6 Chlorophyll
Chlorophyll content, as expected, was high in the immature olives and rapidly decreased with time as the colour changed from green to black. All cultivars showed a temporary increase at the beginning of the season in chlorophyll content during ripening in 2004 (Figure 3.18a, b, c). Chlorophyll content was also higher in all cultivars throughout the season in 2004 than in other years. This was unexpected but again the overall trend for the three years was a gradual decline in chlorophyll as the fruit matured. There was a significant year effect for the Paragon and Corregiolla cultivars (p = 0.033 and p = 0.003 respectively), although not for the Mission cultivar
(p = 0.322). All cultivars showed a significant effect due to time of harvest (p <
0.02). There was no irrigation effect for chlorophyll for any of the cultivars studied.
Chlorophyll has been shown in previous studies to contribute to oil stability whilst kept in the dark, or in intact fruit (Boskou 1996). However, chlorophyll captures light and will become a pro-oxidant after the oil is extracted. The stage of olive maturity is important for chlorophyll concentration in the oil. Chlorophyll concentrations are high in fruit which has been harvested early in the season. At the end of maturity late in the season, its concentration diminishes to a few parts per million and xanthophylls, a similar pigment compound, although also at low levels, become the main constituents of olive oil pigments (Gandul-Rojas et al. 1996).
Chlorophyll is seen as a positive characteristic for olive oil as it provides the green colour to the oil. However, to take advantage of the aesthetic value, it is necessary to store the bottle in clear glass which would therefore contribute to oxidation due to the action of light and reduced shelf life of the oil (see Section 1.2.4). The green colour is generally a sign that the oil is relatively fresh as oil stored in the light will gradually lose the green colour and turn golden yellow.
104 (a)
2002 20 Corregiolla 2003 2004
15
10
Chlorophyll (mg/kg oil) 5
0
(b)
20 Mission 2002 2003 2004
15
10
Chlorophyll (mg/kg oil) 5
0
(c)
20 2002 2003 2004
15
10
Chlorophyll oil) (mg/kg 5
0
80 100 120 140 160 180 200 220 Days after January 1 Figure 3.18 Chlorophyll content for three cultivars (a) Corregiolla, (b) Mission and (c)
Paragon, over three years. Each point represents the mean of nine replicates ± standard error.
105 3.6.7 α-Tocopherol
α−tocopherol, or Vitamin E, is a strong antioxidant. This component was only measured in 2004 when the method had been established. All cultivars showed a trend to decrease in tocopherol content as the fruit matured (Figure 3.19). The order of α-tocopherol content for each cultivar was the inverse of polyphenols with
Mission having the lowest concentration and Paragon the highest.
There was a significant time of harvest effect for all cultivars (p < 0.001 for
Paragon and Corregiolla and p = 0.002 for Mission). There were no significant irrigation effects for any of the cultivars studied. The results from this research are similar to those found by Garcia et al. (1996b), who found that the cultivars which they studied (Verdial and Villalonga) also exhibited significant effects due to time of harvest.
500 α- tocopherols Corregiolla 450 Mission Paragon
400
350
300
250
alpha-tocopherol (mg/kg) alpha-tocopherol 200
150
100 80 100 120 140 160 180 200 Days after January 1
Figure 3.19 α-tocopherols content for three cultivars (a) Corregiolla, (b) Mission and (c)
Paragon, in 2004. Each point represents the mean of nine replicates ± standard error.
106 4 Chapter 4 Conclusions and future studies
This study has highlighted the changes which occur in olive oil during fruit maturation. The trees utilised were very young at only four to seven years of age.
Although this is typical of many new groves around Australia, it will not reflect the olive groves of the future. There are several suggestions about the advantages of old trees over young ones, such as a perceived improvement in oil sensory characteristics.
This study also included an examination of irrigation effects on fruit and oil quality, although the environmental conditions over three years were less than ideal with drought persisting over the period. Water was limiting and there were few significant differences between high irrigation, moderate deficit irrigation and severe deficit irrigation treatments. The study, however, did provide considerable information on soil water movements and their effects on some of the properties of the fruit and oil.
Some physical parameters changed during the maturation of the fruit.
Moisture content tended to decrease over the growing period but the Mission cultivar differed from the other cultivars in that it maintained a more constant moisture content throughout the growing period. Moisture content of the fruit is an important factor to growers, as large amounts of moisture in the fruit tend to produce emulsions when the fruit is processed, making separation of the oil difficult.
The quality of the oil obtained from the trees examined in this study showed dramatic differences over the three years, especially shown by the changes in polyphenol content, fatty acid profile, free fatty acids, and chlorophyll content of the oil.
107 Polyphenol content was higher each year as the study progressed. In relation to polyphenols, which contribute to pungency and bitterness in the oil, all of the samples tested showed progressive changes in oil sensory characteristics. Oil shelf life stability, as measured by induction time, also increased over the three years. The changes during the three years may be related to the progressively worsening drought or to better establishment of root growth and greater uniformity of the trees. It is difficult to confirm that this is due to tree maturity over three years and the study should be continued for several years to establish the influence of tree age on oil quality during conditions when drought does not occur.
The fatty acid profile is important for oil stability and also for its nutritional quality. Although oleic acid content changed little over the maturity period in this study, linoleic acid (polyunsaturated) content was found to increase while palmitic acid (saturated) decreased. Linolenic acid also decreased with maturity. This component is unstable and can increase the rate of oxidation. The linolenic acid needs to be below 1.0%, according to IOOC regulations, which usually occurs early in the maturity process.
Free fatty acids must be less than 0.8% in extra virgin olive oil, according to
IOOC regulations. From this study, it can be seen that it is necessary to harvest olives, particularly cultivars such as Paragon, before free fatty acids increase later in the season.
Chlorophyll provides aesthetic qualities to the oil which please consumers, but it also has pro-oxidant properties when exposed to light, contributing to a loss of oil quality. This study showed early harvesting can achieve higher levels of chlorophyll than harvesting later in the season.
This study was limited to a single orchard in southern New South Wales. It has been shown through a study of fatty acid profiles undertaken by the Oils
108 Research Laboratory, Department of Primary Industries, Wagga Wagga, that fatty acid profiles show significant variation between northern regions of Australia and the south (unpublished data). Oleic acid is consistently higher in oils from Victoria and
Tasmania than in oils from Queensland and palmitic acid is lower. Other unknown factors may also contribute to variability in oil quality.
Only three cultivars were included in this study. It is estimated that ten main cultivars constitute 90% of Australian olive trees. Chemical analyses of oils from the range of these trees across the Australian growing region, has shown considerable variation in a limited number of tests (Mailer 2005). Future studies should include a wide range of cultivars from a wide range of locations.
An expanded study to take in groves in different environments is essential to determine the results of oil produced under a wide range of conditions. A more comprehensive study of the oil from such a study would be beneficial to growers. Oil components such as individual polyphenols and their relationships to oil stability, sterols and the effect of latitude and environment could be studied. A more comprehensive study of the effect of irrigation on oil components would also be useful.
Harvest timing does have a significant effect on olive oil quality. The conditions of this study showed that early harvest leads to longer shelf life and improved aesthetic qualities such as high chlorophyll content. However, due to significant differences between years, it is difficult to determine an optimal harvest time. Although the irrigation practices used in this study were far from ideal, it was proven in some cases, that irrigation does have a significant effect on the quality of the olive oil produced.
The Australian olive oil industry is still in its infancy. While olive oil industries have been operating in other countries for hundreds, sometimes thousands
109 of years and are therefore well established, the Australian industry can use its relative lack of experience and infrastructure to its advantage. New technologies such as regulated deficit irrigation, mechanical harvesters, orchard design and processing infrastructure are more easily implemented in Australia than in other well established olive oil industries overseas. While all of these factors are important, understanding aspects of harvest timing and irrigation allows producers to ensure the quality of the fruit, and therefore the olive oil they produce, is at its optimum.
110 5 Chapter 5
5.1 References
Andrikopoulos, N., Hassapidou, M., and Manoukas, A. (1989) "The tocopherol
content of Greek olive oils." Journal of the Science of Food and Agriculture
46: 503-509.
AOCS (American oil chemists society). (1998). Official methods and recommended
practices of the American Oil Chemists’ Society. 5th edition. AOCS Press,
Champaign, Illinois.
Aparicio, R. and Luna, G. (2002) "Characterisation of monovarietal virgin olive
oils." European Journal of Lipid Science and Technology 104: 614-627.
Ayton, J., Mailer, R., Robards, K., Orchard, B. and Vonarx, M. (2001) "Oil
concentration and composition of olives during fruit maturation in south-
western New South Wales." Australian Journal of Experimental Agriculture
41: 815-821.
Braverman, J.B.S. (1976) The biochemistry of foods. Elsevier Scientific Publishing
Co., Amsterdam, Netherlands.
Boskou, D. (1996) Olive Oil Chemistry and Technology. AOCS Press, Champaign.
Caponio, F. and Gomes, T. (2001) "Phenolic compounds in virgin olive oils:
influence of the degree of olive ripeness on organoleptic characteristics and
shelf life." European Journal of Food Research and Technology 212: 329-
333.
Cert, A., Alba, J., Perez-Camino, M., Ruiz-Gomez, A., Hidalgo, F., Moreda, W.,
Moyano, M., Martinez, F., Tubaileh, R. and Olias, J. (1999) "Influence of
extraction methods on the characteristics and minor components of extra
virgin olive oil." Olivae 79: 41-50.
111 Connell, J. (1994) "History and scope of the olive industry." In Olive production
manual. Ferguson, L., Sibbett, G. and Martin, G. (Eds). University of
California, Oakland pp. 1-11. d'Andria, R., Morelli, G., Giorio, P., Patumi, M., Vergari, G. and Fontanazza, G.
(1999) "Yield and oil quality of young olive trees grown under
differentirrigation regimes." Acta Horticulturae 474: 185-188.
Delbridge, A., Ed. (1982) The concise Macquarie dictionary. Doubleday Australia
Pty Ltd, Sydney.
Di Giovacchino, L., Sestili, S. and Di Vincenzo, D. (2002) "Influence of olive
processing on virgin olive oil quality." European Journal of Lipid Science
and Technology 104: 587-601.
El Antari, A., Hilal, A., Boulouha, B. and El Moudni, A. (2000) "Influence of the
variety, environment and cultural techniques on the characteristics of olive
fruits and the chemical composition of extra virgin olive oil in Morocco."
Olivae 80: 29-36.
Ferguson, L., Sibbett, G. and Martin, G. (1994) Olive production manual. University
of California, Oakland.
Fernandez, J.E. and Moreno F. (1999) "Water Use by the Olive Tree." Journal of
Crop Production 2: 101-162.
Gandul-Rojas, B. and Minguez-Mosquera, M.I. (1996) "Chlorophyll and carotenoid
composition in virgin olive oils from various Spanish olive varieties."
Journal of the Science of Food and Agriculture 72: 31-39.
Garcia, J., Gutierrez, F., Barrera, M. and Albi, M. (1996a) "Storage of mill olives on
an industrial scale." Journal of Agricultural and Food Chemistry 44: 590-
593.
112 Garcia, J., Seller, S. and Perez-Camino, M. (1996b) "Influence of fruit ripening on
olive oil quality." Journal of Agricultural and Food Chemistry 44: 3516-
3520.
Giametta, G. (1992) "Mecahnical harvesting of olives: Present situation and
prospects." Acta Horticulturae 321: 510-517.
Gimeno, E., Castellote, A., Lamuela-Raventos, R., De la Torre, M. and Lopez-
Sabater, M. (2002) "The effects of harvest and extraction methods on the
antioxidant content (phenolics, α-tocopherol, and β-carotene) in virgin olive
oil." Food Chemistry 78: 207-211.
Grati-Kammoun, N., Khlif, M., Rekik, H. and Hamdi, M.T. (1999) "Evolution of oil
characteristics during olive maturation (Chemlali variety)". Proceedings of
the 3rd International ISHS Symposium on Olive Growing: Acta Horticulturae
474: 701-704.
Gutfinger, T. (1981) “Polyphenols in olive oils.” Journal of the American Oil
Chemists' Society 62: 895-898.
Gutierrez, F., Jimenez, B., Ruiz, A. and Albi, M. (1999) "Effect of olive ripeness on
the oxidative stability of virgin olive oil extracted from the varieties Picual
and Hojiblanca and on the different components involved." Journal of
Agricultural and Food Chemistry 47: 121-127.
Gutierrez Rosales, F., Garrido-Fernandez, J., Gallardo-Guerrero, L., Gandul-Rojas
B. and Minguez-Mosquera, M. (1992a) "Action of chlorophylls on the
stability of virgin olive oil." Journal of the American Oil Chemists' Society
69: 866-871.
Gutierrez Rosales, F., Perdiguero, S., Gutierrez, R. and Olias, J. (1992b) "Evaluation
of the bitter taste in virgin olive oil." Journal of the American Oil Chemists'
Society 69: 394-395.
113 Harwood, J. and Aparicio, R., Eds. (2000a) Handbook of olive oil: Analysis and
properties. Technological aspects. Gaithersburg, Aspen Publishers.
Harwood, J. and Aparicio, R., Eds. (2000b) Handbook of olive oil: Analysis and
properties. Analysis of edible oils. Aspen Publishers, Gaithersburg.
Inglese, P., Barone, E. and Gullo, G. (1996) "The effect of complimentary irrigation
on fruit growth, ripening pattern and oil characteristics of olive (Olea
europaea L.) cv. Carolea." Journal of Horticultural Science 71: 257-263
IOOC (International Olive Oil Council) (no date shown) International olive oil
council, http://www.international oliveoil.org/downloads/
importations1_ang.PDF (date accessed 27/1/05).
IUPAC (International Union of Pure and Applied Chemistry). (1992) Standard
methods for the analysis of oils, fats and derivatives. 7th edition. Blackwell
Scientific Publications, Oxford, United Kingdom.
Jesus Tovar, M., Jose Moltiva, M. and Paz Romero, M. (2001a) "Changes in the
phenolic composition of virgin olive oil from young trees (Olea europaea
L.cv. Arbequina) grown under linear irrigation strategies." Journal of
Agricultural and Food Chemistry 49: 5502-5508.
Jesus Tovar, M., Jose Moltiva, M., Luna, M., Girona, J. and Paz Romero, M. (2001b)
"Analytical characteristics of virgin olive oil from young trees (Arbequina
cultivar) growing under linear irrigation strategies." Journal of the American
Oil Chemists' Society 78: 843-849.
Jose Moltiva, M., Jesus Tovar, M., Paz Romero, M., Alegre, S. and Girona, J. (2000)
"Influence of regulated deficit irrigation strategies applied to olive trees
(Arbequina cultivar) on oil yield and oil composition during the fruit ripening
period." Journal of the Science of Food and Agriculture 80: 2037-2043.
114 Kiritsakis, A., Kanavouras, A. and Kiritsakis, K. (2002) "Chemical analysis, quality
control and packaging issues of olive oil." European Journal of Lipid Science
and Technology 104: 628-638.
Kiritsakis, A.K. (1998) Olive oil from the tree to the table. 2nd edn. Food and
Nutrition Press, Inc., Trumbull, Connecticut, United States of America.
Koprivnjak, O. and Conte, L. (1998) "Specific components of virgin olive oil as
active participants in oxidative processes." Food Technology and
Biotechnology 36: 223-234.
Koutsaftakis, A., Kotsifaki, F., Stefanoudaki, E. and Cert, A. (2000) "A three year
study on the variations of several chemical characterstics and other minor
components of virgin olive oils extracted from olives harvested at different
ripening stages." Olivae 80: 22-27.
Lantzke, N. and Taylor, R. (2001) Irrigation of olives in Western Australia.
Agriculture Western Australia, Perth.
Lavee, S. (1996) Biology and physiology of the olive. World Olive Encyclopaedia.
International Olive Oil Council, Madrid: pp 61-110.
Lawson, H. (1995) Food oils and fats. Chapman-Hall, Melbourne.
Lopez-Villalta, L. (1996) Production techniques. World olive encyclopaedia.
International Olive Oil Council, Madrid: pp 145-190.
Luchetti, F. (2002) "Importance and future of olive oil in the world market - an
introduction to olive oil." European Journal of Lipid Science and Technology
104: 559-563.
Mailer, R.J. Ayton, J. and Conlan, D. (2002) “Comparison and evaluation of the
quality of thirty eight commercial Australian and New Zealand olive oils.”
Advances in Horticultural Science 16: 259-266.
115 Mailer, R.J., (2005) "Variation in oil quality and fatty acid composition in Australian
olive oil." Australian Journal of Experimental Agriculture 45: 115-119.
Michelakis, N., Vouyoukalou, E. and Clapaki, G. (1995) "Plant growth and yield
response of the olive tree cv. Kalamon, for different levels of soil water
potential and methods of irrigation." Advances in Horticultural Science 9:
136-139.
Miller, P. (2002) Building a quality olive industry through modern practices.
Australian Olive Association National Olive Industry Convention
Proceedings, Brisbane, Australia.
Moltiva, M., Romero, M., Alegre, S. and Girona, J. (1999) "Effect of regulated
defecit irrigation in olive oil production and quality." Acta Horticulturae 474:
377-380.
Morello, J., Moltiva, M., Ramo T. and Romero, M. (2003) "Effect of freeze injuries
in olive fruit on olive oil composition." Food Chemistry 81: 547-553
Mousa, Y., Gerasopoulos, D., Metzidakis, I. and Kiritsakis, A. (1996) "Effect of
altitude on fruit and oil quality characteristics of Mastoides olives." Journal
of the Science of Food and Agriculture 71: 345-350.
Parr, J. and Bolwell, G. (2000) "Phenols in the plant and in man. The potential for
possible nutritional enhancement of the diet by modifying the phenols content
or profile." Journal of the Science of Food and Agriculture 80: 985-1012.
Patumi, M., d'Andria, R., Marsilio, V., Fontanazza, G., Morelli, G. and Lanza, B.
(2002) "Olive and olive oil quality after intensive monoclone olive growing
(Olea europaea L. cv. Kalamata) in different irrigation regimes." Food
Chemistry 77: 27-34.
Patumi, M., d'Andria, R., Fontanazza, G., Morelli, G., Giorio, P. and Sorrentino, G.
(1999) "Yield and oil quality of intensively trained trees of three cultivars of
116 olive (Olea europaea L.) under different irrigation regimes." Journal of
Horticultural Science and Biotechnology 74: 729-737.
Paz Romero, M., Jesus Tovar, M., Ramo, T. and Jose Moltiva, M. (2003) "Effect of
crop season on the composition of virgin olive oil with protected designation
of origin "Les Garrigues"." Journal of the American Oil Chemists' Society
80: 423-430.
Pereira, J., Casal, S., Bento, A. and Oliveira, M. (2002) "Influence of olive storage
period on oil quality of three Portuguese cultivars of Olea europaea,
Cobrancosa, Madural, and Verdeal Transmontana." Journal of Agricultural
and Food Chemistry 50: 6335-6340.
Psomiadou, E. and Tsimidou, M. (2001) "Pigments in Greek virgin olive oils:
occurrence and levels." Journal of the Science of Food and Agriculture 81:
640-647.
Psomiadou, E. and Tsimidou, M. (2002) "Stability of virgin olive oil. 2. Photo-
oxidation studies." Journal of Agricultural and Food Chemistry 50: 722-727.
Rahmani, M., Lamrini, M. and Saari Csallany, A. (1997) "Development of a simple
method for the determination of the optimum harvesting date for olives."
Olivae 69: 48-51.
Ranalli, A., Tombesi, A., Ferrante, M.L. and De Mattia, G. (1998) “Respiratory rate
of olive drupes during their ripening cycle and quality of oil extracted.”
Journal of Science and Food in Agriculture 77: 359-367.
Robards, K., Kerr, A. and Patsalides, E. (1988) "Rancidity and its measurement in
edible oils and snack food." Analyst 113: 213.
Robbelen, G., Downey, R. and Ashri, A. Eds. (1989) Oil crops of the world. Olive.
McGraw-Hill Publishing company, Sydney.
117 Ryan, D., Robards, K. and Lavee, S. (1998) "Assessment of quality in olive oil."
Olivae 72: 23-41.
Salvador, M., Aranda, F. and Fregapane, G. (1998) "Chemical composition of
commercial Cornicabra virgin olive oil from 1995/1996 and 1996/1997
crops." Journal of the American Oil Chemists' Society 75: 1305-1311.
Salvador, M., Aranda, F. and Fregapane, G. (1999) "Contribution of chemical
components of Cornicabra virgin olive oils to oxidative stability. A study of
three successive crop seasons." Journal of the American Oil Chemists'
Society 76: 427-432.
Salvador, M., Aranda, F. and Fregapane, G. (2001) "Influence of fruit ripening on
Cornicabra virgin olive oil quality. A study of four successive crop seasons."
Food Chemistry 79: 45-53.
Sanchez-Raya, A.J. (1983) “Physiological parameters of growth and ripening in olive
fruit (Olea europaea L.)” Fruit Science Reports 4:145-160.
Servilli, M., Baldioli, M., Selvaggini, R., Miniati, E., Macchioni, A. and Montedoro,
G. (1999) "High performance liquid chromatography evaluation of phenols in
olive fruit, virgin olive oil, vegetation waters, and pomace and 1D and 2D
nuclear magnetic resonance characterization." Journal of the American Oil
Chemists' Society 76: 873-882.
Skevin, D., Rade, D., Strucelj, D., Mokrovcak, Z., Nederal, S. and Bencic, D. (2003)
"The influence of variety and harvest time on the bitterness and phenolic
compounds of olive oil." European Journal of Food Research and
Technology 105: 536-541.
Smyth, J. (2002) "Perspectives of the Australian olive industry." Advances in
Horticultural Science 16: 280-88.
118 Soler-Rivas, C., Carlos Espin, J. and Wichers, H. (2000) "Oleuropein and related
compounds." Journal of the Science of Food and Agriculture 80: 1013-1023.
Spennemann, D. (1999) Centenary of olive processing at Charles Sturt University.
Charles Sturt University, Wagga Wagga.
Spennemann, D. and Allen, L. (2000) "Feral olives (Olea europaea) as future woody
weeds in Australia: a review." Australian Journal of Experimental
Agriculture 40: 889-901.
Tayfun Agar, I., Hess-Pierce, B., Sourour, M. and Kader, A. (1998) "Quality of fruit
and oil of black ripe olives is influenced by cultivar and storage period."
Journal of Agricultural and Food Chemistry 46: 3415-3421.
Tombesi, A. (1990) "Physiological and mechanical advances in olive harvesting."
Acta Horticulturae 286: 399-412.
Tovar, M., Romero, M., Alegre, S., Girona, J. and Moltiva, M. (2002) "Composition
and organoleptic characteristics of oil from Arbequina Olive (Olea europaea
L.) trees under deficit irrigation." Journal of the Science of Food and
Agriculture 82: 1755-1763.
Tsimidou, M. (1998) "Polyphenols and quality of virgin olive oil in retrospect."
Italian Journal of Food Science 10: 99-115.
Tuck, K. and Hayball, J. (2002) "Major phenolic compounds in olive oil: metabolism
and health effects." The Journal of Nutritional Biochemistry 13: 636-644.
Velasco, J. and Dobarganes, C. (2002) "Oxidative stability of virgin olive oil."
European Journal of Lipid Science and Technology 104: 661-676.
Wahrburg, U., Kratz, M. and Cullen, P. (2002) "Mediterranean diet, olive oil and
health." European Journal of Lipid Science and Technology 104: 698-705.
119 6 Chapter 6
6.1 Appendices
Analysis of variance for the varieties Mission, Corregiolla, and Paragon. * The denominator degrees of freedom used in the calculation of the P- value was determined using Kenward adjustments (as implemented in ASReml).
Table 6.1 Table of P-Values from the analysis of the variety Paragon.
Term Moisture Polyphenol Induction C18.1 C18.2 C18.3 C16.0 Chloro %FFA Perox Toco Mature
Year 0.452 <0.001 <0.001 <0.001 <0.001 0.014 <0.001 0.033 <0.001 0.001 NA 0.163
Irr 0.477 <0.001 <0.001 0.753 0.529 0.592 0.755 0.057 0.296 0.002 0.298 0.622
Year:Irr 0.680 0.001 <0.001 0.776 0.900 0.235 0.246 0.120 0.122 0.176 NA 0.162
Lin(Time) 0.026 <0.001 <0.001 0.123 0.011 <0.001 <0.001 0.019 <0.001 0.233 <0.001 0.015
Year:Lin(Time) 0.012 <0.001 <0.001 0.017 <0.001 0.007 0.188 0.152 0.002 0.300 NA 0.087
Irr:Lin(Time) 0.799 0.117 0.309 0.576 0.528 0.256 0.730 0.095 0.006 0.830 0.474 0.811
Year:Irr:Lin(Time) 0.956 0.470 0.244 0.055 0.229 0.082 0.423 0.073 0.056 0.282 NA 0.576
Table 6.2 Table of P-Values from the analysis of the variety Corregiolla.
Term Moisture Polyphenol Induction C18.1 C18.2 C18.3 C16.0 Chloro %FFA Perox Toco Mature
Year 0.053 <0.001 <0.001 <0.001 <0.001 0.228 <0.001 0.003 0.050 0.010 NA 0.006
Irr 0.986 0.184 0.417 0.292 0.578 0.467 0.077 0.633 0.091 0.193 0.479 0.820
Year:Irr 0.580 0.839 0.969 0.169 0.263 0.392 0.158 0.897 0.887 0.046 NA 0.495
Lin(Time) <0.001 <0.001 0.002 0.283 <0.001 0.087 <0.001 0.016 <0.001 0.358 <0.001 <0.001
Year:Lin(Time) 0.033 0.014 0.068 <0.001 <0.001 0.009 0.026 0.057 0.006 0.141 NA 0.169
Irr:Lin(Time) 0.880 0.533 0.633 0.579 0.643 0.230 0.687 0.764 0.077 0.350 0.362 0.948
Year:Irr:Lin(Time) 0.907 0.535 0.518 0.075 0.368 0.022 0.034 0.713 0.635 0.727 NA 0.739
Table 6.3 Table of P-Values from the analysis of the variety Mission.
Term Moisture Polyphenol Induction C18.1 C18.2 C18.3 C16.0 Chloro %FFA Perox Toco Mature
Year <0.001 0.009 0.002 0.033 0.024 0.019 <0.001 0.322 0.044 <0.001 NA 0.401
Irr 0.470 0.787 0.462 0.042 0.214 0.890 0.056 0.262 0.283 0.149 0.331 0.199
Year:Irr 0.868 0.508 0.506 0.476 0.596 0.797 0.203 0.284 0.372 0.276 NA 0.191
Lin(Time) 0.019 0.010 0.043 0.599 <0.001 <0.001 <0.001 0.003 0.092 0.018 0.002 0.005
Year:Lin(Time) 0.008 0.651 0.417 0.008 0.052 0.008 <0.001 0.519 0.002 0.075 NA 0.710
Irr:Lin(Time) 0.126 0.211 0.752 0.761 0.645 0.131 0.746 0.275 0.156 0.389 0.414 0.705
Year:Irr:Lin(Time) 0.844 0.614 0.799 0.210 0.295 0.432 0.170 0.543 0.347 0.969 NA 0.077
121 Corregiola
60 65 70 75 0.5 1.0 1.5 2.0
induct 2610
C18.1 60 70
C18.2 10 20
C18.3 0.5 1.5
C16.0 11 14 17
24681012 10 15 20 11 13 15 17
Figure 6.1 Relationships between induction time and fatty acids C16:0, C18:1, C18:2 and C18:3.
122 Corregiola
10 15 20 0.2 0.4 0.6 0.8
induct 2610
C18.2 10 20
chloro 01020
Ffatacid 0.2 0.5 0.8
perox 4812
24681012 0 5 10 15 20 468101214
Figure 6.2 Relationships between induction time and C18:2, chlorophyll, free fatty acid and peroxide value.
123 Experimental data
% Free Peroxide Fatty Acid Value (mEq α Cold Press % (as oleic Induction Time Polyphenols (mg Chlorophyll oxygen/kg Maturity tocopherols Harvest Date Variety Treatment Rep # % Moisture Oil (wt/wt) acid) (hours) caffeic / kg Oil) (mg/kg) oil) Index (mg/kg)
28/02/2002 Corregiolla G 1 56.18 ------28/02/2002 Corregiolla G 2 56.58 ------28/02/2002 Corregiolla G 3 55.82 ------28/02/2002 Corregiolla R 1 56.29 ------28/02/2002 Corregiolla R 2 54.72 ------28/02/2002 Corregiolla R 3 55.25 ------28/02/2002 Corregiolla Y 1 60.52 ------28/02/2002 Corregiolla Y 2 56.30 ------28/02/2002 Corregiolla Y 3 55.43 ------28/02/2002 Mission G 1 59.24 ------28/02/2002 Mission G 2 57.28 ------28/02/2002 Mission G 3 58.30 ------28/02/2002 Mission R 1 57.72 ------28/02/2002 Mission R 2 57.23 ------28/02/2002 Mission R 3 57.62 ------28/02/2002 Mission Y 1 57.70 ------28/02/2002 Mission Y 2 57.49 ------28/02/2002 Mission Y 3 58.07 ------28/02/2002 Paragon G 1 55.66 ------28/02/2002 Paragon G 2 55.28 ------28/02/2002 Paragon G 3 56.84 ------28/02/2002 Paragon R 1 53.03 ------28/02/2002 Paragon R 2 55.34 ------28/02/2002 Paragon R 3 54.79 ------28/02/2002 Paragon Y 1 54.30 ------28/02/2002 Paragon Y 2 54.28 ------28/02/2002 Paragon Y 3 54.42 ------
25/03/2002 Corregiolla G 1 58.65 ------25/03/2002 Corregiolla G 2 57.71 ------25/03/2002 Corregiolla G 3 53.49 ------25/03/2002 Corregiolla R 1 56.25 ------25/03/2002 Corregiolla R 2 56.55 ------25/03/2002 Corregiolla R 3 55.90 ------25/03/2002 Corregiolla Y 1 61.97 ------
124 % Free Peroxide Fatty Acid Value (mEq α Cold Press % (as oleic Induction Time Polyphenols (mg Chlorophyll oxygen/kg Maturity tocopherols Harvest Date Variety Treatment Rep # % Moisture Oil (wt/wt) acid) (hours) caffeic / kg Oil) (mg/kg) oil) Index (mg/kg) 25/03/2002 Corregiolla Y 2 56.74 ------25/03/2002 Corregiolla Y 3 52.36 ------25/03/2002 Mission G 1 57.60 ------25/03/2002 Mission G 2 59.06 ------25/03/2002 Mission G 3 59.06 ------25/03/2002 Mission R 1 56.31 ------25/03/2002 Mission R 2 57.01 ------25/03/2002 Mission R 3 56.76 ------25/03/2002 Mission Y 1 60.66 ------25/03/2002 Mission Y 2 56.37 ------25/03/2002 Mission Y 3 59.57 ------25/03/2002 Paragon G 1 52.08 ------25/03/2002 Paragon G 2 53.41 ------25/03/2002 Paragon G 3 54.68 ------25/03/2002 Paragon R 1 52.62 ------25/03/2002 Paragon R 2 53.05 ------25/03/2002 Paragon R 3 52.09 ------25/03/2002 Paragon Y 1 54.17 ------25/03/2002 Paragon Y 2 49.10 ------25/03/2002 Paragon Y 3 52.99 ------
8/04/2002 Corregiolla G 1 54.75 13.1 0.14 3.55 125 1.5 9 2.25 - 8/04/2002 Corregiolla G 2 54.90 12.5 0.20 3.22 202 2.0 12 2.66 - 8/04/2002 Corregiolla G 3 58.41 10.5 0.26 2.80 126 3.8 10 2.66 - 8/04/2002 Corregiolla R 1 57.08 11.8 0.21 3.02 146 2.7 9 2.97 - 8/04/2002 Corregiolla R 2 56.65 13.1 0.23 3.22 140 4.6 15 3.39 - 8/04/2002 Corregiolla R 3 58.54 12.4 0.27 2.70 105 3.8 13 2.55 - 8/04/2002 Corregiolla Y 1 67.07 8.5 0.14 4.80 420 6.2 14 3.35 - 8/04/2002 Corregiolla Y 2 58.76 10.5 0.23 2.88 97 2.8 8 2.29 - 8/04/2002 Corregiolla Y 3 55.13 11.8 0.19 3.23 157 2.7 12 2.83 - 8/04/2002 Mission G 1 58.63 13.1 0.19 8.25 583 14.4 13 1.87 - 8/04/2002 Mission G 2 59.12 11.8 0.21 8.65 691 10.5 14 1.90 - 8/04/2002 Mission G 3 60.56 12.4 0.18 6.77 409 6.2 10 2.42 - 8/04/2002 Mission R 1 57.62 12.5 0.21 6.60 491 6.6 13 2.85 - 8/04/2002 Mission R 2 60.27 11.8 0.25 7.98 522 5.6 12 2.36 - 8/04/2002 Mission R 3 60.48 11.8 0.20 7.62 522 9.3 14 1.91 - 8/04/2002 Mission Y 1 60.18 11.2 0.17 7.47 603 8.7 10 1.83 -
125 % Free Peroxide Fatty Acid Value (mEq α Cold Press % (as oleic Induction Time Polyphenols (mg Chlorophyll oxygen/kg Maturity tocopherols Harvest Date Variety Treatment Rep # % Moisture Oil (wt/wt) acid) (hours) caffeic / kg Oil) (mg/kg) oil) Index (mg/kg) 8/04/2002 Mission Y 2 55.12 13.1 0.24 8.70 700 10.3 14 1.88 - 8/04/2002 Mission Y 3 61.59 9.8 0.22 10.10 852 9.1 7 1.66 - 8/04/2002 Paragon G 1 53.03 14.4 0.23 3.78 178 2.1 11 2.76 - 8/04/2002 Paragon G 2 52.42 14.4 0.18 3.13 87 7.0 15 2.11 - 8/04/2002 Paragon G 3 55.74 13.1 0.16 2.87 139 3.5 10 2.67 - 8/04/2002 Paragon R 1 53.20 14.5 0.22 3.68 209 5.0 11 1.96 - 8/04/2002 Paragon R 2 55.70 12.5 0.18 4.78 114 3.2 11 2.04 - 8/04/2002 Paragon R 3 53.62 13.8 0.15 2.70 104 3.2 12 1.95 - 8/04/2002 Paragon Y 1 51.93 15.7 0.22 3.47 257 2.9 11 2.43 - 8/04/2002 Paragon Y 2 49.62 18.4 0.23 3.47 151 6.8 16 2.53 - 8/04/2002 Paragon Y 3 53.74 13.8 0.18 2.63 97 5.0 13 1.94 -
30/04/2002 Corregiolla G 1 56.76 7.8 0.29 2.22 57 0.6 - 3.16 - 30/04/2002 Corregiolla G 2 52.25 11.8 0.26 2.42 116 0.2 - 3.67 - 30/04/2002 Corregiolla G 3 50.46 12.4 0.26 2.07 73 1.0 - 3.61 - 30/04/2002 Corregiolla R 1 53.98 12.4 0.30 2.13 84 1.3 - 3.08 - 30/04/2002 Corregiolla R 2 50.75 7.9 0.26 2.17 127 0.0 - 4.24 - 30/04/2002 Corregiolla R 3 50.38 15.6 0.29 2.22 74 1.2 - 4.16 - 30/04/2002 Corregiolla Y 1 61.60 5.3 0.14 4.25 206 0.0 - 3.75 - 30/04/2002 Corregiolla Y 2 52.12 12.2 0.29 2.27 89 1.8 - 2.63 - 30/04/2002 Corregiolla Y 3 39.04 21.6 0.34 2.70 148 2.8 - 3.97 - 30/04/2002 Mission G 1 51.49 17.1 0.29 4.50 234 3.2 - 3.38 - 30/04/2002 Mission G 2 61.13 11.8 0.25 7.13 389 5.6 - 2.35 - 30/04/2002 Mission G 3 57.30 11.8 0.22 6.00 318 1.5 - 2.86 - 30/04/2002 Mission R 1 49.82 17.1 0.23 4.62 195 2.5 - 2.75 - 30/04/2002 Mission R 2 60.54 10.5 0.22 5.23 214 2.8 - 3.47 - 30/04/2002 Mission R 3 55.49 11.8 0.30 5.38 233 2.5 - 2.71 - 30/04/2002 Mission Y 1 59.05 10.5 0.24 4.80 244 2.0 - 3.08 - 30/04/2002 Mission Y 2 53.93 14.4 0.22 6.75 318 4.2 - 3.58 - 30/04/2002 Mission Y 3 57.55 13.1 0.22 8.02 455 2.5 - 2.28 - 30/04/2002 Paragon G 1 44.28 23.7 0.33 2.67 139 1.9 - 3.53 - 30/04/2002 Paragon G 2 46.24 19.7 0.25 3.72 204 3.1 - 3.39 - 30/04/2002 Paragon G 3 44.58 12.4 0.26 2.42 113 1.1 - 3.49 - 30/04/2002 Paragon R 1 44.73 19.0 0.25 2.48 120 1.3 - 2.60 - 30/04/2002 Paragon R 2 44.79 19.0 0.27 2.80 94 2.2 - 3.40 - 30/04/2002 Paragon R 3 41.96 18.3 0.22 3.40 136 2.0 - 3.35 - 30/04/2002 Paragon Y 1 43.92 18.4 0.30 2.50 130 2.2 - 3.47 -
126 % Free Peroxide Fatty Acid Value (mEq α Cold Press % (as oleic Induction Time Polyphenols (mg Chlorophyll oxygen/kg Maturity tocopherols Harvest Date Variety Treatment Rep # % Moisture Oil (wt/wt) acid) (hours) caffeic / kg Oil) (mg/kg) oil) Index (mg/kg) 30/04/2002 Paragon Y 2 43.03 22.3 0.32 2.28 130 4.3 - 3.37 - 30/04/2002 Paragon Y 3 43.72 21.0 0.38 2.55 126 3.4 - 2.85 -
23/05/2002 Corregiolla G 1 50.74 13.1 0.29 2.22 65 0.7 8 3.62 - 23/05/2002 Corregiolla G 2 48.72 17.0 0.38 2.25 74 0.7 9 3.88 - 23/05/2002 Corregiolla G 3 43.09 14.4 0.42 2.27 92 0.9 13 3.56 - 23/05/2002 Corregiolla R 1 56.77 11.8 0.43 1.48 58 0.2 10 4.43 - 23/05/2002 Corregiolla R 2 43.71 15.8 0.49 1.92 70 0.3 14 3.89 - 23/05/2002 Corregiolla R 3 50.53 13.1 0.65 1.70 95 0.3 15 4.28 - 23/05/2002 Corregiolla Y 1 57.81 9.2 0.22 4.25 190 0.6 7 4.00 - 23/05/2002 Corregiolla Y 2 53.03 13.1 0.38 2.43 71 1.6 10 3.48 - 23/05/2002 Corregiolla Y 3 47.31 15.7 0.59 1.47 66 0.6 13 2.81 - 23/05/2002 Mission G 1 44.43 19.7 0.47 2.42 113 1.7 13 3.92 - 23/05/2002 Mission G 2 60.55 10.5 0.25 3.68 186 0.6 12 4.08 - 23/05/2002 Mission G 3 58.97 11.8 0.75 2.85 140 1.4 15 4.79 - 23/05/2002 Mission R 1 51.70 17.1 0.85 2.50 126 1.7 14 5.71 - 23/05/2002 Mission R 2 59.86 10.5 0.27 4.93 207 1.5 10 4.52 - 23/05/2002 Mission R 3 57.24 13.1 0.33 4.15 217 1.5 12 4.66 - 23/05/2002 Mission Y 1 57.14 13.1 0.35 3.60 176 1.9 12 4.82 - 23/05/2002 Mission Y 2 52.50 14.4 0.37 4.77 231 1.9 11 4.59 - 23/05/2002 Mission Y 3 64.62 7.9 0.22 5.13 266 0.7 9 4.55 - 23/05/2002 Paragon G 1 37.73 26.1 0.70 2.38 121 2.1 13 3.85 - 23/05/2002 Paragon G 2 38.22 23.6 0.29 3.13 107 1.7 9 3.46 - 23/05/2002 Paragon G 3 44.22 22.3 0.48 2.03 70 1.3 15 3.94 - 23/05/2002 Paragon R 1 39.74 22.3 0.34 2.65 87 1.5 12 3.72 - 23/05/2002 Paragon R 2 41.73 20.4 0.39 2.40 80 2.1 10 3.51 - 23/05/2002 Paragon R 3 39.42 17.0 0.38 2.60 95 1.5 9 4.30 - 23/05/2002 Paragon Y 1 38.72 23.7 0.44 1.77 97 1.1 13 4.02 - 23/05/2002 Paragon Y 2 40.71 22.3 0.42 2.40 93 1.1 11 4.48 - 23/05/2002 Paragon Y 3 41.11 21.7 0.36 2.73 90 3.8 12 2.87 -
8/07/2002 Corregiolla G 1 45.19 15.1 0.49 1.67 40 0.4 8 4.68 - 8/07/2002 Corregiolla G 2 42.74 19.0 0.70 1.85 75 1.0 12 3.49 - 8/07/2002 Corregiolla G 3 39.42 19.6 0.59 2.80 109 1.2 12 3.98 - 8/07/2002 Corregiolla R 1 44.07 18.4 0.46 1.83 88 0.7 10 3.33 -
127 % Free Peroxide Fatty Acid Value (mEq α Cold Press % (as oleic Induction Time Polyphenols (mg Chlorophyll oxygen/kg Maturity tocopherols Harvest Date Variety Treatment Rep # % Moisture Oil (wt/wt) acid) (hours) caffeic / kg Oil) (mg/kg) oil) Index (mg/kg) 8/07/2002 Corregiolla R 2 42.74 23.6 0.68 1.63 41 1.6 13 4.27 - 8/07/2002 Corregiolla R 3 39.51 23.6 0.77 2.67 116 1.6 13 4.00 - 8/07/2002 Corregiolla Y 1 47.12 13.1 0.20 4.63 151 0.7 4 4.00 - 8/07/2002 Corregiolla Y 2 41.21 23.0 0.57 1.73 72 0.5 10 4.12 - 8/07/2002 Corregiolla Y 3 40.48 21.8 0.70 1.47 89 0.4 13 4.50 - 8/07/2002 Mission G 1 49.71 14.4 0.70 1.98 79 0.5 12 4.50 - 8/07/2002 Mission G 2 57.16 9.2 0.33 2.77 111 0.4 9 4.37 - 8/07/2002 Mission G 3 58.17 11.2 0.52 2.00 79 0.3 10 4.98 - 8/07/2002 Mission R 1 52.37 11.8 0.79 1.37 56 0.3 14 4.63 - 8/07/2002 Mission R 2 54.96 10.7 0.57 2.47 91 0.5 10 4.42 - 8/07/2002 Mission R 3 52.05 13.1 0.63 2.90 128 0.3 8 5.19 - 8/07/2002 Mission Y 1 57.88 5.9 0.38 2.68 99 0.3 10 4.74 - 8/07/2002 Mission Y 2 54.55 13.1 0.50 2.83 111 0.5 10 5.29 - 8/07/2002 Mission Y 3 63.33 9.1 0.39 3.68 132 1.0 8 4.10 - 8/07/2002 Paragon G 1 35.81 28.7 1.45 2.38 73 1.3 16 4.12 - 8/07/2002 Paragon G 2 36.26 27.5 0.91 2.03 105 1.1 9 5.50 - 8/07/2002 Paragon G 3 37.56 24.9 0.89 1.60 76 1.0 15 4.00 - 8/07/2002 Paragon R 1 37.54 28.9 0.90 1.75 67 1.8 14 4.36 - 8/07/2002 Paragon R 2 34.91 27.6 0.97 2.05 73 1.3 11 4.00 - 8/07/2002 Paragon R 3 38.56 27.5 0.64 3.12 119 1.4 9 4.03 - 8/07/2002 Paragon Y 1 36.84 27.4 0.97 1.85 171 1.6 13 4.12 - 8/07/2002 Paragon Y 2 32.67 30.2 0.88 2.92 131 2.0 11 4.72 - 8/07/2002 Paragon Y 3 36.31 26.3 0.91 3.44 79 1.7 13 3.80 -
17/02/2003 Corregiolla G 1 56.81 ------0.00 - 17/02/2003 Corregiolla G 2 58.06 ------0.00 - 17/02/2003 Corregiolla G 3 56.34 ------0.00 - 17/02/2003 Corregiolla R 1 55.31 ------0.00 - 17/02/2003 Corregiolla R 2 60.06 ------0.00 - 17/02/2003 Corregiolla R 3 58.25 ------0.00 - 17/02/2003 Corregiolla Y 1 55.04 ------0.00 - 17/02/2003 Corregiolla Y 2 55.06 ------0.00 - 17/02/2003 Corregiolla Y 3 56.23 ------0.00 - 17/02/2003 Mission G 1 53.48 ------0.00 - 17/02/2003 Mission G 2 51.30 ------0.00 - 17/02/2003 Mission G 3 56.52 ------0.00 - 17/02/2003 Mission R 1 53.67 ------0.00 -
128 % Free Peroxide Fatty Acid Value (mEq α Cold Press % (as oleic Induction Time Polyphenols (mg Chlorophyll oxygen/kg Maturity tocopherols Harvest Date Variety Treatment Rep # % Moisture Oil (wt/wt) acid) (hours) caffeic / kg Oil) (mg/kg) oil) Index (mg/kg) 17/02/2003 Mission R 2 53.72 ------0.00 - 17/02/2003 Mission R 3 57.64 ------0.00 - 17/02/2003 Mission Y 1 51.52 ------0.00 - 17/02/2003 Mission Y 2 47.92 ------0.00 - 17/02/2003 Mission Y 3 57.24 ------0.00 - 17/02/2003 Paragon G 1 53.15 ------0.00 - 17/02/2003 Paragon G 2 51.61 ------0.00 - 17/02/2003 Paragon G 3 51.22 ------0.00 - 17/02/2003 Paragon R 1 53.62 ------0.00 - 17/02/2003 Paragon R 2 52.25 ------0.00 - 17/02/2003 Paragon R 3 54.12 ------0.00 - 17/02/2003 Paragon Y 1 51.47 ------0.00 - 17/02/2003 Paragon Y 2 51.20 ------0.00 - 17/02/2003 Paragon Y 3 52.67 ------0.00 -
18/03/2003 Corregiolla G 1 57.22 ------1.29 - 18/03/2003 Corregiolla G 2 56.07 ------1.35 - 18/03/2003 Corregiolla G 3 56.01 ------1.18 - 18/03/2003 Corregiolla R 1 54.00 ------1.05 - 18/03/2003 Corregiolla R 2 54.80 ------1.36 - 18/03/2003 Corregiolla R 3 54.78 ------1.06 - 18/03/2003 Corregiolla Y 1 55.38 ------1.41 - 18/03/2003 Corregiolla Y 2 58.08 ------1.13 - 18/03/2003 Corregiolla Y 3 56.16 ------1.07 - 18/03/2003 Mission G 1 50.09 ------1.12 - 18/03/2003 Mission G 2 53.57 ------1.26 - 18/03/2003 Mission G 3 55.13 ------1.20 - 18/03/2003 Mission R 1 53.70 ------1.06 - 18/03/2003 Mission R 2 51.80 ------1.17 - 18/03/2003 Mission R 3 53.29 ------1.10 - 18/03/2003 Mission Y 1 54.58 ------1.14 - 18/03/2003 Mission Y 2 51.74 ------1.08 - 18/03/2003 Mission Y 3 54.18 ------1.06 - 18/03/2003 Paragon G 1 48.61 ------1.12 - 18/03/2003 Paragon G 2 47.84 ------1.19 - 18/03/2003 Paragon G 3 46.63 ------1.20 - 18/03/2003 Paragon R 1 48.42 ------1.42 -
129 % Free Peroxide Fatty Acid Value (mEq α Cold Press % (as oleic Induction Time Polyphenols (mg Chlorophyll oxygen/kg Maturity tocopherols Harvest Date Variety Treatment Rep # % Moisture Oil (wt/wt) acid) (hours) caffeic / kg Oil) (mg/kg) oil) Index (mg/kg) 18/03/2003 Paragon R 2 45.90 ------1.33 - 18/03/2003 Paragon R 3 46.14 ------1.35 - 18/03/2003 Paragon Y 1 49.41 ------1.18 - 18/03/2003 Paragon Y 2 47.11 ------1.10 - 18/03/2003 Paragon Y 3 47.38 ------1.22 -
7/04/2003 Corregiolla G 1 51.33 14.4 0.22 4.78 239 1.81 7.93 3.24 - 7/04/2003 Corregiolla G 2 52.57 13.1 0.27 6.98 381 6.38 7.58 3.03 - 7/04/2003 Corregiolla G 3 50.57 13.1 0.23 6.57 354 4.76 8.00 2.74 - 7/04/2003 Corregiolla R 1 50.17 14.4 0.30 5.78 381 1.70 8.39 3.00 - 7/04/2003 Corregiolla R 2 51.16 13.1 0.24 7.00 341 3.98 6.07 2.87 - 7/04/2003 Corregiolla R 3 48.18 13.1 0.24 6.75 376 3.06 6.57 2.87 - 7/04/2003 Corregiolla Y 1 50.46 14.4 0.21 6.67 301 2.04 10.08 1.63 - 7/04/2003 Corregiolla Y 2 51.00 14.4 0.22 6.05 356 1.80 7.76 2.92 - 7/04/2003 Corregiolla Y 3 54.32 13.1 0.23 6.98 404 5.28 6.23 2.93 - 7/04/2003 Mission G 1 48.03 13.0 0.37 10.90 870 10.97 5.44 3.13 - 7/04/2003 Mission G 2 51.21 6.6 0.22 9.60 793 3.03 4.32 2.58 - 7/04/2003 Mission G 3 51.54 7.9 0.26 10.20 767 8.29 5.20 3.60 - 7/04/2003 Mission R 1 51.46 11.8 0.35 9.30 718 4.35 5.91 2.89 - 7/04/2003 Mission R 2 47.77 9.2 0.27 10.90 698 8.64 6.79 3.00 - 7/04/2003 Mission R 3 48.40 9.2 0.26 9.93 713 4.06 4.24 3.07 - 7/04/2003 Mission Y 1 49.91 10.5 0.39 11.20 856 6.00 4.73 3.60 - 7/04/2003 Mission Y 2 49.66 11.8 0.31 10.50 857 5.47 4.97 2.94 - 7/04/2003 Mission Y 3 58.02 5.2 0.17 6.10 334 1.10 5.37 3.13 - 7/04/2003 Paragon G 1 50.53 17.0 0.29 7.70 493 12.21 10.95 3.07 - 7/04/2003 Paragon G 2 50.46 16.9 0.28 7.33 584 6.54 10.33 3.38 - 7/04/2003 Paragon G 3 52.59 15.8 0.26 5.28 379 3.59 11.27 3.16 - 7/04/2003 Paragon R 1 40.38 20.9 0.29 9.77 746 11.08 5.28 3.94 - 7/04/2003 Paragon R 2 41.12 21.1 0.30 8.45 678 7.20 7.37 3.86 - 7/04/2003 Paragon R 3 41.64 19.7 0.28 9.03 610 7.62 6.48 3.70 - 7/04/2003 Paragon Y 1 47.99 18.3 0.29 8.23 632 13.61 7.53 3.54 - 7/04/2003 Paragon Y 2 53.43 17.0 0.25 8.08 598 7.63 8.64 3.08 - 7/04/2003 Paragon Y 3 48.16 15.7 0.25 7.25 538 4.35 10.41 2.94 -
30/04/2003 Corregiolla G 1 48.45 13.1 0.24 4.48 194 0.7 7.4 3.00 - 30/04/2003 Corregiolla G 2 51.89 14.4 0.31 4.47 284 2.8 8.2 3.64 -
130 % Free Peroxide Fatty Acid Value (mEq α Cold Press % (as oleic Induction Time Polyphenols (mg Chlorophyll oxygen/kg Maturity tocopherols Harvest Date Variety Treatment Rep # % Moisture Oil (wt/wt) acid) (hours) caffeic / kg Oil) (mg/kg) oil) Index (mg/kg) 30/04/2003 Corregiolla G 3 55.31 13.0 0.26 4.55 285 1.1 7.0 2.89 - 30/04/2003 Corregiolla R 1 49.98 18.3 0.36 4.78 352 1.3 7.4 3.07 - 30/04/2003 Corregiolla R 2 51.42 15.1 0.30 4.85 303 0.9 7.4 2.84 - 30/04/2003 Corregiolla R 3 58.11 9.2 0.22 5.22 220 1.1 5.7 2.10 - 30/04/2003 Corregiolla Y 1 53.53 11.8 0.30 5.62 445 1.3 7.4 2.59 - 30/04/2003 Corregiolla Y 2 51.15 13.1 0.26 4.05 261 1.1 7.9 3.14 - 30/04/2003 Corregiolla Y 3 53.37 15.7 0.24 4.43 159 1.9 5.6 3.74 - 30/04/2003 Mission G 1 47.78 18.4 0.29 8.68 612 3.2 6.5 3.45 - 30/04/2003 Mission G 2 52.43 15.7 0.30 9.53 687 5.3 3.5 3.37 - 30/04/2003 Mission G 3 56.47 10.5 0.21 7.03 402 1.5 6.0 3.34 - 30/04/2003 Mission R 1 50.80 15.7 0.34 10.20 838 7.0 9.3 3.25 - 30/04/2003 Mission R 2 52.99 15.8 0.26 8.93 594 9.6 10.2 3.30 - 30/04/2003 Mission R 3 52.79 17.0 0.28 10.20 608 6.2 7.3 2.94 - 30/04/2003 Mission Y 1 52.20 13.1 0.28 9.18 632 2.7 5.3 3.15 - 30/04/2003 Mission Y 2 52.90 11.7 0.29 10.90 710 3.6 6.9 2.78 - 30/04/2003 Mission Y 3 55.19 14.5 0.24 7.85 432 2.5 6.5 2.80 - 30/04/2003 Paragon G 1 46.12 22.2 0.30 5.35 376 3.2 10.5 3.31 - 30/04/2003 Paragon G 2 45.81 22.3 0.30 5.73 436 2.1 8.1 3.65 - 30/04/2003 Paragon G 3 45.57 23.6 0.32 5.92 368 4.2 11.4 3.68 - 30/04/2003 Paragon R 1 42.39 22.2 0.28 4.80 325 1.1 6.6 4.00 - 30/04/2003 Paragon R 2 46.32 23.5 0.26 6.45 429 3.4 10.3 3.53 - 30/04/2003 Paragon R 3 43.57 23.5 0.24 8.02 495 3.3 5.4 3.83 - 30/04/2003 Paragon Y 1 47.63 22.3 0.34 6.17 440 5.2 11.8 3.16 - 30/04/2003 Paragon Y 2 43.46 22.3 0.21 7.40 593 1.2 4.6 4.03 - 30/04/2003 Paragon Y 3 44.88 22.2 0.33 5.82 372 5.4 12.9 3.67 -
28/05/2003 Corregiolla G 1 44.24 13.07 0.34 3.60 136 1.55 7.9 3.81 - 28/05/2003 Corregiolla G 2 38.58 19.70 0.35 4.35 159 1.50 7.8 3.44 - 28/05/2003 Corregiolla G 3 46.16 21.53 0.27 4.85 159 1.78 7.6 3.74 - 28/05/2003 Corregiolla R 1 39.06 23.57 0.39 4.12 359 1.42 8.1 4.25 - 28/05/2003 Corregiolla R 2 43.11 23.55 0.36 4.10 162 1.21 9.0 4.08 - 28/05/2003 Corregiolla R 3 46.12 14.39 0.32 4.40 189 1.58 6.9 3.00 - 28/05/2003 Corregiolla Y 1 42.11 17.68 0.30 6.98 260 2.51 6.3 2.84 - 28/05/2003 Corregiolla Y 2 43.16 23.56 0.37 4.27 143 1.29 8.2 3.87 - 28/05/2003 Corregiolla Y 3 41.33 22.34 0.42 4.22 174 4.70 7.9 3.32 - 28/05/2003 Mission G 1 42.33 22.27 0.22 9.13 632 2.68 4.1 4.21 - 28/05/2003 Mission G 2 42.45 18.30 0.21 7.52 434 1.54 5.7 4.59 -
131 % Free Peroxide Fatty Acid Value (mEq α Cold Press % (as oleic Induction Time Polyphenols (mg Chlorophyll oxygen/kg Maturity tocopherols Harvest Date Variety Treatment Rep # % Moisture Oil (wt/wt) acid) (hours) caffeic / kg Oil) (mg/kg) oil) Index (mg/kg) 28/05/2003 Mission G 3 47.30 18.25 0.22 9.12 473 2.45 5.0 3.79 - 28/05/2003 Mission R 1 45.42 22.20 0.26 8.53 452 2.96 6.3 4.25 - 28/05/2003 Mission R 2 44.14 16.96 0.22 7.00 346 0.77 3.8 4.40 - 28/05/2003 Mission R 3 45.22 18.38 0.26 7.52 426 2.43 5.4 3.96 - 28/05/2003 Mission Y 1 44.79 17.04 0.24 8.12 477 1.15 5.1 4.08 - 28/05/2003 Mission Y 2 43.86 18.31 0.21 8.08 495 2.14 7.0 4.14 - 28/05/2003 Mission Y 3 49.48 14.43 0.21 6.93 317 1.65 5.9 4.35 - 28/05/2003 Paragon G 1 39.11 27.53 0.28 5.35 227 2.44 8.4 4.27 - 28/05/2003 Paragon G 2 39.45 26.11 0.33 5.58 234 2.10 9.7 3.96 - 28/05/2003 Paragon G 3 40.63 26.20 0.44 4.17 198 1.36 13.5 3.91 - 28/05/2003 Paragon R 1 39.48 27.56 0.29 5.58 262 1.22 6.6 4.47 - 28/05/2003 Paragon R 2 38.10 31.38 0.33 5.38 245 1.62 7.9 3.90 - 28/05/2003 Paragon R 3 32.40 27.53 0.24 6.57 346 0.90 4.9 4.31 - 28/05/2003 Paragon Y 1 39.02 26.10 0.34 5.58 264 3.53 9.4 4.03 - 28/05/2003 Paragon Y 2 36.88 27.60 0.37 4.75 219 2.95 9.6 3.83 - 28/05/2003 Paragon Y 3 38.66 27.47 0.46 4.42 236 1.17 11.6 4.10 -
15/07/2003 Corregiolla G 1 43.08 15.77 0.81 2.53 120 1.17 10.4 3.88 - 15/07/2003 Corregiolla G 2 41.57 14.40 0.61 2.67 110 0.91 8.6 4.52 - 15/07/2003 Corregiolla G 3 40.53 17.07 0.53 4.07 162 1.20 7.8 4.05 - 15/07/2003 Corregiolla R 1 40.92 13.13 0.75 2.60 104 4.28 9.0 3.94 - 15/07/2003 Corregiolla R 2 44.81 15.78 0.59 2.77 117 0.82 7.9 4.70 - 15/07/2003 Corregiolla R 3 44.11 16.98 0.51 4.17 166 1.06 8.9 4.03 - 15/07/2003 Corregiolla Y 1 43.39 13.09 0.35 4.58 174 0.47 6.9 4.44 - 15/07/2003 Corregiolla Y 2 36.84 18.36 0.60 2.65 143 0.52 8.5 4.29 - 15/07/2003 Corregiolla Y 3 40.10 18.31 0.65 3.43 197 0.98 9.1 4.01 - 15/07/2003 Mission G 1 40.79 8.52 0.31 5.20 288 0.13 5.4 4.65 - 15/07/2003 Mission G 2 39.15 4.59 0.21 4.23 211 0.09 5.4 5.20 - 15/07/2003 Mission G 3 44.81 5.57 0.14 3.63 186 0.07 5.1 5.18 - 15/07/2003 Mission R 1 44.67 6.55 0.49 4.42 226 0.19 6.7 4.92 - 15/07/2003 Mission R 2 45.87 7.22 0.10 4.30 262 0.15 5.1 5.20 - 15/07/2003 Mission R 3 41.83 7.84 0.22 4.20 234 0.06 5.4 5.40 - 15/07/2003 Mission Y 1 44.98 6.55 0.26 4.88 236 -0.04 5.3 5.26 - 15/07/2003 Mission Y 2 43.91 7.84 0.18 3.83 247 0.10 7.0 6.00 - 15/07/2003 Mission Y 3 47.18 2.61 0.32 - - 0.08 4.7 5.30 - 15/07/2003 Paragon G 1 38.03 22.36 0.82 3.67 186 1.04 11.8 4.08 - 15/07/2003 Paragon G 2 37.89 23.63 0.98 2.93 198 0.87 10.8 4.32 -
132 % Free Peroxide Fatty Acid Value (mEq α Cold Press % (as oleic Induction Time Polyphenols (mg Chlorophyll oxygen/kg Maturity tocopherols Harvest Date Variety Treatment Rep # % Moisture Oil (wt/wt) acid) (hours) caffeic / kg Oil) (mg/kg) oil) Index (mg/kg) 15/07/2003 Paragon G 3 38.52 18.25 0.86 3.53 197 0.79 11.6 4.09 - 15/07/2003 Paragon R 1 37.48 23.46 0.57 5.23 279 0.62 5.3 4.12 - 15/07/2003 Paragon R 2 36.59 26.08 0.81 3.82 190 4.87 5.6 4.49 - 15/07/2003 Paragon R 3 40.59 23.45 0.52 4.17 226 0.53 4.1 4.00 - 15/07/2003 Paragon Y 1 36.89 26.25 0.70 4.47 235 0.63 8.6 4.52 - 15/07/2003 Paragon Y 2 35.51 22.19 0.82 2.85 154 0.56 9.8 4.37 - 15/07/2003 Paragon Y 3 41.21 19.61 0.50 4.65 225 0.79 8.0 4.21 -
18/02/2004 Corregiolla G 1 51.57 ------0.00 - 18/02/2004 Corregiolla G 2 48.92 ------0.00 - 18/02/2004 Corregiolla G 3 51.60 ------0.00 - 18/02/2004 Corregiolla R 1 55.61 ------0.00 - 18/02/2004 Corregiolla R 2 53.63 ------0.00 - 18/02/2004 Corregiolla R 3 51.52 ------0.00 - 18/02/2004 Corregiolla Y 1 50.51 ------0.00 - 18/02/2004 Corregiolla Y 2 51.98 ------0.00 - 18/02/2004 Corregiolla Y 3 49.94 ------0.00 - 18/02/2004 Mission G 1 47.29 ------0.00 - 18/02/2004 Mission G 2 46.28 ------0.00 - 18/02/2004 Mission G 3 48.48 ------0.00 - 18/02/2004 Mission R 1 45.45 ------0.00 - 18/02/2004 Mission R 2 50.75 ------0.00 - 18/02/2004 Mission R 3 50.21 ------0.00 - 18/02/2004 Mission Y 1 49.76 ------0.00 - 18/02/2004 Mission Y 2 47.08 ------0.00 - 18/02/2004 Mission Y 3 51.99 ------0.00 - 18/02/2004 Paragon G 1 43.01 ------0.00 - 18/02/2004 Paragon G 2 40.72 ------0.00 - 18/02/2004 Paragon G 3 45.80 ------0.00 - 18/02/2004 Paragon R 1 45.89 ------0.00 - 18/02/2004 Paragon R 2 46.82 ------0.00 - 18/02/2004 Paragon R 3 50.52 ------0.00 - 18/02/2004 Paragon Y 1 45.11 ------0.00 - 18/02/2004 Paragon Y 2 48.08 ------0.00 - 18/02/2004 Paragon Y 3 42.69 ------0.00 -
18/03/2004 Corregiolla G 1 55.15 ------0.00 -
133 % Free Peroxide Fatty Acid Value (mEq α Cold Press % (as oleic Induction Time Polyphenols (mg Chlorophyll oxygen/kg Maturity tocopherols Harvest Date Variety Treatment Rep # % Moisture Oil (wt/wt) acid) (hours) caffeic / kg Oil) (mg/kg) oil) Index (mg/kg) 18/03/2004 Corregiolla G 2 55.38 ------0.83 - 18/03/2004 Corregiolla G 3 54.31 ------1.00 - 18/03/2004 Corregiolla R 1 55.79 ------0.21 - 18/03/2004 Corregiolla R 2 40.01 ------0.00 - 18/03/2004 Corregiolla R 3 55.43 ------0.07 - 18/03/2004 Corregiolla Y 1 55.01 ------0.09 - 18/03/2004 Corregiolla Y 2 50.22 ------1.06 - 18/03/2004 Corregiolla Y 3 44.40 ------0.69 - 18/03/2004 Mission G 1 56.44 ------0.68 - 18/03/2004 Mission G 2 56.07 ------1.40 - 18/03/2004 Mission G 3 58.15 ------0.65 - 18/03/2004 Mission R 1 39.38 ------1.39 - 18/03/2004 Mission R 2 43.86 ------1.96 - 18/03/2004 Mission R 3 49.11 ------1.38 - 18/03/2004 Mission Y 1 47.14 ------1.64 - 18/03/2004 Mission Y 2 45.07 ------1.87 - 18/03/2004 Mission Y 3 47.77 ------1.35 - 18/03/2004 Paragon G 1 53.20 ------0.21 - 18/03/2004 Paragon G 2 53.14 ------0.50 - 18/03/2004 Paragon G 3 51.59 ------0.22 - 18/03/2004 Paragon R 1 41.01 ------0.00 - 18/03/2004 Paragon R 2 42.93 ------0.00 - 18/03/2004 Paragon R 3 39.73 ------0.00 - 18/03/2004 Paragon Y 1 42.82 ------0.00 - 18/03/2004 Paragon Y 2 40.91 ------0.00 - 18/03/2004 Paragon Y 3 44.22 ------0.00 -
13/04/2004 Corregiolla G 1 55.73 9.8 0.23 13.1 669 13.8 8.0 1.27 261 13/04/2004 Corregiolla G 2 54.95 9.2 0.19 11.2 496 7.6 7.2 1.23 360 13/04/2004 Corregiolla G 3 54.70 10.5 0.18 10.1 454 9.0 6.8 1.05 315 13/04/2004 Corregiolla R 1 56.39 11.1 0.25 10.3 767 11.3 6.1 2.29 402 13/04/2004 Corregiolla R 2 56.36 9.8 0.27 11.5 815 14.0 6.8 2.45 466 13/04/2004 Corregiolla R 3 55.21 9.8 0.21 9.85 631 10.1 7.2 0.60 355 13/04/2004 Corregiolla Y 1 52.83 10.5 0.22 12.6 637 11.2 7.7 1.14 365 13/04/2004 Corregiolla Y 2 57.42 10.5 0.24 12.15 723 14.6 9.7 1.91 371 13/04/2004 Corregiolla Y 3 54.33 9.2 0.22 10.2 626 12.8 5.4 1.96 347 13/04/2004 Mission G 1 53.90 11.1 0.31 11.0 785 9.6 8.3 1.36 286 13/04/2004 Mission G 2 53.07 9.8 0.29 11.2 798 9.1 5.0 2.01 240
134 % Free Peroxide Fatty Acid Value (mEq α Cold Press % (as oleic Induction Time Polyphenols (mg Chlorophyll oxygen/kg Maturity tocopherols Harvest Date Variety Treatment Rep # % Moisture Oil (wt/wt) acid) (hours) caffeic / kg Oil) (mg/kg) oil) Index (mg/kg) 13/04/2004 Mission G 3 57.17 10.5 0.24 10.7 652 8.9 7.0 1.62 288 13/04/2004 Mission R 1 51.10 7.2 0.18 7.50 438 14.8 6.3 2.29 605 13/04/2004 Mission R 2 53.33 10.5 0.28 11.65 887 6.9 9.1 2.99 277 13/04/2004 Mission R 3 55.61 11.1 0.25 10.2 708 9.1 5.4 2.34 261 13/04/2004 Mission Y 1 57.28 9.2 0.28 10.3 715 7.7 4.7 3.09 324 13/04/2004 Mission Y 2 51.91 9.5 0.27 10.75 764 7.0 6.0 3.46 278 13/04/2004 Mission Y 3 58.20 6.6 0.20 10.7 704 6.9 5.2 2.83 306 13/04/2004 Paragon G 1 54.15 9.2 0.17 8.72 405 14.1 6.6 1.23 347 13/04/2004 Paragon G 2 53.23 9.2 0.17 8.00 401 7.7 8.9 1.58 398 13/04/2004 Paragon G 3 52.04 9.9 0.17 6.70 358 5.8 8.0 1.73 329 13/04/2004 Paragon R 1 55.15 9.2 0.19 10.95 601 21.0 8.3 1.74 393 13/04/2004 Paragon R 2 55.26 10.5 0.21 11.8 692 12.9 5.7 1.95 352 13/04/2004 Paragon R 3 56.71 8.5 0.23 11.4 653 15.0 5.3 1.51 483 13/04/2004 Paragon Y 1 56.18 8.8 0.18 10.5 571 10.9 6.0 2.04 471 13/04/2004 Paragon Y 2 57.21 9.8 0.21 10.70 600 19.5 7.7 2.07 518 13/04/2004 Paragon Y 3 57.38 11.1 0.23 11.5 696 17.0 5.0 1.98 447
5/05/2004 Corregiolla G 1 48.22 15.0 0.31 12.8 729 14.2 10.6 2.47 250 5/05/2004 Corregiolla G 2 45.16 17.0 0.29 9.98 539 8.6 9.6 2.62 215 5/05/2004 Corregiolla G 3 45.31 15.7 0.23 9.65 550 20.5 13.5 1.57 257 5/05/2004 Corregiolla R 1 47.24 17.0 0.30 10.9 717 9.1 7.2 3.03 235 5/05/2004 Corregiolla R 2 47.87 15.7 0.30 12.40 822 17.0 5.7 2.64 288 5/05/2004 Corregiolla R 3 47.46 15.7 0.27 10.50 158 15.4 6.1 2.10 275 5/05/2004 Corregiolla Y 1 49.34 14.4 0.31 10.9 641 9.6 7.6 2.29 112 5/05/2004 Corregiolla Y 2 45.07 15.1 0.29 11.2 710 13.2 6.3 2.49 206 5/05/2004 Corregiolla Y 3 40.58 17.0 0.22 10.24 660 14.8 5.8 3.77 325 5/05/2004 Mission G 1 44.45 19.7 0.30 9.83 798 11.3 5.0 2.99 244 5/05/2004 Mission G 2 45.79 14.4 0.33 11.7 903 9.2 4.8 3.50 0 5/05/2004 Mission G 3 47.20 17.1 0.26 8.70 570 8.7 9.3 3.63 170 5/05/2004 Mission R 1 46.61 17.7 0.21 9.47 673 9.5 5.4 3.11 247 5/05/2004 Mission R 2 48.78 14.4 0.34 12.6 863 10.5 5.8 3.11 234 5/05/2004 Mission R 3 43.92 15.8 0.34 10.5 920 8.6 4.2 3.73 197 5/05/2004 Mission Y 1 48.61 13.8 0.25 10.6 727 6.1 7.0 3.69 136 5/05/2004 Mission Y 2 45.98 14.4 0.33 10.9 870 10.9 4.6 4.31 213 5/05/2004 Mission Y 3 47.44 13.8 0.32 11.25 923 7.9 5.0 3.14 171 5/05/2004 Parragon G 1 39.09 19.6 0.21 7.83 551 19.4 11.1 3.25 357 5/05/2004 Parragon G 2 39.14 17.1 0.21 9.40 476 17.1 9.6 3.04 322 5/05/2004 Parragon G 3 41.55 18.3 0.23 8.82 540 14.4 11.2 2.99 283
135 % Free Peroxide Fatty Acid Value (mEq α Cold Press % (as oleic Induction Time Polyphenols (mg Chlorophyll oxygen/kg Maturity tocopherols Harvest Date Variety Treatment Rep # % Moisture Oil (wt/wt) acid) (hours) caffeic / kg Oil) (mg/kg) oil) Index (mg/kg) 5/05/2004 Parragon R 1 39.46 19.0 0.16 11.60 802 21.2 4.1 2.87 347 5/05/2004 Parragon R 2 39.95 20.4 0.34 12.75 827 22.6 4.9 2.70 340 5/05/2004 Parragon R 3 40.21 21.0 0.26 12.1 760 20.7 6.8 2.88 360 5/05/2004 Parragon Y 1 43.55 16.8 0.24 9.22 634 20.4 7.0 3.08 222 5/05/2004 Parragon Y 2 38.15 17.7 0.25 9.47 653 24.3 8.4 1.96 391 5/05/2004 Parragon Y 3 42.90 16.7 0.21 11.00 645 16.8 6.5 3.02 265
31/05/2004 Corregiolla G 1 46.33 19.6 0.26 9.82 577 4.8 6.3 3.87 235 31/05/2004 Corregiolla G 2 46.57 18.4 0.20 9.22 464 5.5 6.0 3.85 258 31/05/2004 Corregiolla G 3 45.39 18.3 0.18 9.2 479 4.3 5.1 3.93 276 31/05/2004 Corregiolla R 1 44.99 19.7 0.20 9.43 649 3.2 4.2 4.33 255 31/05/2004 Corregiolla R 2 46.54 19.0 0.21 11.3 778 5.8 2.6 4.15 254 31/05/2004 Corregiolla R 3 45.06 19.7 0.24 - 536 4.6 5.2 3.77 199 31/05/2004 Corregiolla Y 1 45.95 17.0 0.22 11.3 700 7.7 3.0 3.92 293 31/05/2004 Corregiolla Y 2 46.91 17.4 0.23 10.2 712 8.1 2.7 3.83 287 31/05/2004 Corregiolla Y 3 46.08 18.0 0.17 9.02 670 7.4 3.9 3.97 281 31/05/2004 Mission G 1 47.19 18.3 0.21 9.15 665 2.5 4.3 4.80 226 31/05/2004 Mission G 2 48.79 11.2 0.17 8.83 539 2.2 3.5 4.50 180 31/05/2004 Mission G 3 45.67 14.4 0.21 7.58 517 1.4 4.1 4.70 158 31/05/2004 Mission R 1 46.69 12.5 0.23 7.99 568 1.0 3.6 4.60 220 31/05/2004 Mission R 2 49.29 16.4 0.27 10.4 758 3.9 3.2 4.30 216 31/05/2004 Mission R 3 47.13 15.1 0.20 8.31 613 2.1 3.8 4.38 167 31/05/2004 Mission Y 1 46.64 10.2 0.22 8.39 636 1.8 2.3 4.90 196 31/05/2004 Mission Y 2 46.73 11.8 0.25 8.63 608 2.5 2.5 4.80 209 31/05/2004 Mission Y 3 49.05 11.5 0.22 9.53 597 3.1 3.1 4.41 182 31/05/2004 Paragon G 1 47.34 15.7 0.16 - 571 5.9 3.2 4.08 331 31/05/2004 Paragon G 2 46.22 17.1 0.18 8.79 449 5.0 3.4 3.98 224 31/05/2004 Paragon G 3 46.39 15.7 0.18 9.43 527 5.2 4.4 3.97 306 31/05/2004 Paragon R 1 47.83 18.3 0.20 10.3 652 9.2 4.5 4.00 315 31/05/2004 Paragon R 2 48.03 20.3 0.24 - 853 9.1 3.3 4.04 314 31/05/2004 Paragon R 3 48.82 17.7 0.22 11.6 758 6.9 3.4 4.04 326 31/05/2004 Paragon Y 1 46.29 17.7 0.19 9.5 639 5.5 4.7 4.04 309 31/05/2004 Paragon Y 2 47.27 15.7 0.24 11 797 9.4 4.5 3.98 365 31/05/2004 Paragon Y 3 48.68 16.4 0.19 10.50 550 6.3 3.8 3.89 319
12/07/2004 Corregiolla G 1 44.51 15.7 0.23 10.5 473 2.2 5.3 4.03 156 12/07/2004 Corregiolla G 2 48.35 6.5 - 3.92 330 - 5.0 3.64 202 12/07/2004 Corregiolla G 3 45.79 18.3 0.19 10.7 514 3.8 4.3 3.52 226
136 % Free Peroxide Fatty Acid Value (mEq α Cold Press % (as oleic Induction Time Polyphenols (mg Chlorophyll oxygen/kg Maturity tocopherols Harvest Date Variety Treatment Rep # % Moisture Oil (wt/wt) acid) (hours) caffeic / kg Oil) (mg/kg) oil) Index (mg/kg) 12/07/2004 Corregiolla R 1 46.53 15.7 0.30 6.43 272 2.2 7.4 3.30 139 12/07/2004 Corregiolla R 2 44.55 15.7 0.18 10.2 593 1.9 3.2 4.10 248 12/07/2004 Corregiolla R 3 45.12 16.4 0.63 11.6 399 3.7 4.8 3.47 226 12/07/2004 Corregiolla Y 1 43.43 18.3 0.22 9.62 461 3.7 4.8 3.68 184 12/07/2004 Corregiolla Y 2 43.88 17.0 0.18 10.8 526 2.6 4.8 3.90 213 12/07/2004 Corregiolla Y 3 43.77 15.1 0.22 8.65 485 2.0 3.6 4.16 245 12/07/2004 Mission G 1 48.22 1.3 0.19 - 292 -0.3 2.3 5.90 185 12/07/2004 Mission G 2 51.29 1.3 0.14 7.27 271 0.0 2.0 5.30 168 12/07/2004 Mission G 3 50.12 1.3 0.15 6.25 200 0.1 2.8 5.50 158 12/07/2004 Mission R 1 47.90 1.3 0.14 7.20 336 0.3 2.4 5.60 204 12/07/2004 Mission R 2 49.89 3.3 0.18 7.53 414 0.0 1.8 5.70 167 12/07/2004 Mission R 3 51.10 1.3 0.15 6.58 271 4.2 2.4 5.30 166 12/07/2004 Mission Y 1 52.71 2.6 - - 251 - 2.6 5.50 159 12/07/2004 Mission Y 2 49.41 1.3 - 7.23 357 - 2.0 5.00 178 12/07/2004 Mission Y 3 52.13 2.0 0.10 - 370 - 2.1 5.00 176 12/07/2004 Paragon G 1 43.33 8.5 0.17 6.77 329 0.3 5.0 4.53 263 12/07/2004 Paragon G 2 44.95 10.5 0.15 6.25 308 0.6 4.1 5.00 267 12/07/2004 Paragon G 3 46.08 10.5 0.18 8.05 301 1.1 4.9 4.22 248 12/07/2004 Paragon R 1 46.56 10.4 0.56 9.45 474 1.3 4.0 4.80 226 12/07/2004 Paragon R 2 45.20 9.8 0.17 9.55 413 0.8 3.1 5.10 253 12/07/2004 Paragon R 3 45.91 11.1 0.18 10.2 540 1.2 4.9 4.40 264 12/07/2004 Paragon Y 1 47.34 7.9 0.13 7.92 337 0.6 5.5 4.20 270 12/07/2004 Paragon Y 2 46.25 8.2 0.14 8.70 440 0.9 4.7 4.50 289 12/07/2004 Paragon Y 3 46.56 13.1 0.19 8.92 421 1.4 5.2 4.30 281
137