Effect of Mechanically Harvested Olive Storage Temperature and Duration

et al., 2010; Kalua et al., 2008; Effect of Mechanically Harvested Olive Storage Kiritsakis et al., 1998; Yousfi et al., Temperature and Duration on Oil Quality 2009). Moreover, there is generally no indication of whether the fruit originated from rain-fed or irrigated Arnon Dag1, Smadar Boim, Yulya Sobotin, and Isaac Zipori orchards (Agar et al., 1998; Clodoveo et al., 2007; Dourtoglou et al., 2006; Garcıá et al., 1996; Inarejos-Garcıá ADDITIONAL INDEX WORDS. virgin olive oil, temperature, irrigation, mechanized harvest, polyphenols, free fatty acids, peroxide value et al., 2010; Kalua et al., 2008; Kiritsakis et al., 1998; Yousfi et al., SUMMARY. Most newly planted olive (Olea europaea L.) orchards are irrigated and 2009; Youssef et al., 2011), although harvested mechanically. We assessed the effects of olive storage temperature and we may speculate that those which are duration on the resultant oil’s quality in three cultivars from modern orchards. Oil not indicated originated from rain-fed acidity increased with storage temperature and time, most markedly in ‘Barnea’ and orchards. There are almost no such least in ‘Koroneiki’. In ‘Koroneiki’, after 9 days in cool storage (4 and 10 °C), free fatty acid (FFA) level remained constant. Polyphenol (PP) content behaved studies of fruit originating from mod- differently among cultivars: in ‘Picual’, it was relatively invariable; in ‘Barnea’, it ern, irrigated, and mechanically har- decreased moderately; and in ‘Koroneiki’, it decreased sharply to half of its initial vested orchards, although these are value in 4 °C storage and one-sixth its initial value in room temperature storage after becoming more and more common 23 days. Peroxide value (PV) did not increase during the storage period and did not in olive oil producing countries. appear to be affected by temperature. Thus, different cultivars show different Olives from irrigated trees dem- responses to storage, and fruit originated from modern orchards are not necessarily onstrate an apparent sensitivity to me- more sensitive to storage than those from traditional orchards. chanical wounding, which subsequently leads to increased free acidity and per- live has been grown tradi- develop all kinds of degenerative pro- oxide level, and decreased total phenol tionally for centuries in coun- cesses in a short period of time. The content in the oil (Ben-Gal et al., 2011; Otries of the Mediterranean resultant oils tend to show hydrolytic Dag et al., 2008; Patumi et al., 2002). basin. However, the increase in olive and oxidative deterioration, evident Therefore, their storage capacity might oil consumption related to the per- bytheirhighFFAandPVcontent be limited in comparison with fruit ception of its health-related benefits (Garcıá and Yousfi, 2006). Therefore, originated from traditional rain-fed, (Waterman and Lockwood, 2007) has many studies have explored the proper manually picked orchards. Olive stor- led, in the last two decades, to the way to store olives before processing age is important to balance the rates intensification and expansion of olive to maintain good oil quality. Olive oil of harvest with those of oil extraction cultivation, inside and outside of Med- extraction is often not well synchro- in the mill. The objective of the cur- iterranean countries. According to the nized with crop harvests because of rent work was to evaluate the effect of Food and Agriculture Organization of limited labor and machinery available storage temperatures and duration on the United Nations (FAO), at present for harvest, and the number and size extracted oil quality from commercial, there are 9.4 million hectares of olive of oil extraction facilities (Agar et al., mechanically harvested orchards. orchards in the world, most of which 1998). Therefore, short-term storage are still located in the Mediterranean of olive fruit before oil extraction can Materials and methods basin (FAO, 2012). Traditionally, ol- provide a buffer which will enable more SAMPLES. Olive fruit were obtained ives are not irrigated, but recently efficient use of both harvest facilities from irrigated commercial olive or- water application has been recognized and the mill. chards in Israel: the Israeli cultivar as constructive to 1) increase yields of Several papers have been published Barnea and the Spanish cultivar Picual olives in regions with traditional rain- on the effects of storage length and were obtained from Revivim olive farm fed olive production (Moriana et al., conditions on the resultant oil’s quality. (lat. 31.0500°N, long. 34.4103°E), 2003), 2) allow cultivation in high- However, they generally examine man- and the Greek cultivar Koroneiki was density olive orchards, and 3) expand ually picked fruit (Agar et al., 1998; from Gshur olive farm (lat. 32.7708°N, olive production into regions where Clodoveo et al., 2007; Dourtoglou long. 35.7728°E). In Revivim, trees there is not enough rainfall to support et al., 2006; Garcıá et al., 1996; were at 7 · 3.5-m spacing, with irriga- the crop (Connor, 2005). Today, 25% Kyriakidis and Dourou, 2002; Youssef tion of 800 mm per year, and in to 30% of the olive orchards supplying et al., 2011) or give no indication of Gshur, trees were at 4 · 2-m spacing fruit to the oil extraction industry re- the harvest method (Inarejos-Garcıá with irrigation of 600 mm per year. ceive some level of irrigation (Lavee, 2011). It has been claimed that the great- est deterioration of olive oil quality is Units due to poor handling of the olives To convert U.S. to SI, To convert SI to U.S., between harvest and processing (Olias multiply by U.S. unit SI unit multiply by and Garcıá, 1997). These fruit may 0.4047 acre(s) ha 2.4711 0.3048 ft m 3.2808 25.4 inch(es) mm 0.0394 Gilat Research Center, Agricultural Research Organi- 0.4536 lb kg 2.2046 zation, M.P. Negev 85280, Israel 1 ppm mgÁkg–1 1 1Corresponding author. E-mail: [email protected]. (°F – 32) O 1.8 °F °C(1.8·C) + 32 528 • August 2012 22(4) Fruit were collected immediately after Fullerton, CA) at 735 nm using the on the one hand, and of the mill on commercial mechanical harvest on 16 Folin-Ciocalteu reagent (Swain and the other. Here, we followed the effects Dec. 2009 and brought to the labo- Hillis, 1959). of storage length and temperature on ratory. Harvesting was performed with three major quality parameters in three a commercial linear-vibrating trunk Results and discussion different major olive oil cultivars grown shaker (model D10; Dotan Technol- To produce high-quality oil, it is in intensified orchards. ogies, Migdal HaEmek, Israel) in generally recommended that the ol- I NFLUENCE OF STORAGE Revivim and with a commercial over- ives be processed within 12 to 24 h TEMPERATURE ON FFA LEVEL. In- head mechanical harvester (model VX of harvest (Vossen, 2007). However, creased acidity after fruit storage Braud; New Holland, Coex, France) extension of this period by proper correlates well with decay incidence in Gshur. The olives were randomly storage of the fruit would allow more (Gutie´rrez et al., 1992). In general, the divided into 2-kg lots, which were efficient use of the harvest machinery first action of a parasitic microorganism placed in plastic baskets, each basket considered one replicate. Four replicates were used for each cultivar–storage duration–temperature combination. Ma- turity index (Uceda and Frıás, 1975) was recorded and was 3.6 for ‘Barnea’, 2.6 for ‘Picual’, and 2.0 for ‘Koroneiki’. STORAGE TREATMENTS. Three different storage conditions were tested, two at 4 and 10 °C in refrigerated rooms and a third under ambient conditions (room temperature), with temperatures fluctuating between 12 and 25 °C, as recorded by data logging thermometer. Each storage condition was evaluated for five periods: 1, 5, 9, 16, and 23 d. O IL EXTRACTION AND CHARACTERIZATION. Cold-pressed virgin olive oil was obtained with an ‘‘Abencor’’ system (MC2 Ingenieria y Sistemas, Seville, Spain) as described by Ben-David et al. (2010) for olives originated from irrigated orchards. Tested oil chemical quality parameters were: FFA content, PV, and total PP content. Determinations of FFA content and PV were carried out following International Organization for Standardization (ISO) analytical methods 660 and 3960, respectively. Free acidity (ISO 660), given as per- centage of oleic acid, was determined by titration of a solution of oil in ethanol–ether (1:1, v/v) with ethanolic potassium hydroxide. PV (ISO 3960), expressed in milliequivalents active oxygen (O2) per kilogram oil, was determined as follows: a mixture of oil and isooctane–acetic acid (3:2, v/v) was left to react in the dark with a potassium iodide solution and the free iodine was then titrated with so- dium thiosulfate solution. Phenolic compounds were isolated from a solution of oil in hexane by triple extrac- Fig. 1. Changes in free fatty acid (FFA) content (percent oleic acid) of oils obtained tion with methanol–water (60:40, v/v). from olives stored at different temperatures (4 °C, 10 °C, and room temperature) Total PP, expressed as tyrosol equiv- for different periods of time (1, 5, 9, 16, and 23 d). (A) ‘Barnea’, (B) ‘Picual’, and alents (parts per million), were de- (C) ‘Koroneiki’. Data points represent means of four replicates ± SD. An arrow line is termined with a ultraviolet–visible inserted at 0.8% to indicate the maximal accepted level for extravirgin olive oil; (1.8 · spectrophotometer (Beckman Coulter, °C) + 32 = °F. • August 2012 22(4) 529 PRELIMINARY AND REGIONAL REPORTS in an oil-rich tissue is the induction of temperature, FFA content rose by only oil is well known for its high PP content hydrolytic activity by lipases, which 0.04% during that period.

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