Agric.) University of Alexandria, Egypt

THE YIELD AND CHARACTERISTICS OF GUDEIM (Grewia tenax) JUICE

By Abdalla Elsheikh Mohamed Salih Alrikain B.Sc. (Agric.) University of Alexandria, Egypt

A THESIS SUBMITTED TO THE UNIVERSITY OF KHARTOUM IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE of M.Sc. (Agric.)

Supervisors: Prof. ABDEL MONEIM I. MUSTAFA (Internal Supervisor) FACULTY OF AGRICULTURE, UNIVERSITY OF KHARTOUM and Prof. ELGASIM ALI. ELGASIM (External Supervisor) COLLEGE OF AGRICULTURAL AND FOOD SCIENCES

KING FAISAL UNIVERSITY, K.S.A

Department of Food Science and Technology Faculty of Agriculture, University of Khartoum

August 2004

DEDICATION

First I dedicate this piece of work to my village Wad Alrikain, west of Al-Fao city, where I was born, enjoyed my childhood, and learned how to love my family and my nation. Second I would like to express my most gratitude to the souls of my father, and grand fathers, may Allah host their pure souls in perpetual paradise. Third my deep dedication to my wife, my dear sons and my sweet lovely daughters for their encouragement and interminable support without which this thesis would have never been finished. Moreover, I wish to extend my dedication to my mother, sisters and brothers, without their copious prayers, this study would have never been completed At the end, my dedication is to my teachers, colleagues, friends and all those who offered me their valuable knowledge and trust.

ACKNOWLEDGEMENTS

Foremost, I owe sincere gratitude and praise to Allah Al-Mighty who gave me health and durable patience to finish this study. I would like to express my deepest respect and thanks to my supervisor's Prof. Abdelmoneim Ibrahim Mustafa and Prof. Elgasim Ali Elgasim, for their great assistance, valuable advice, kind supervision and unremitting suggestions through out my master program. My deep thanks to the members of my Master examining committee, to the staff and the head of the department of food science and technology, and to the Dean of the faculty of Agriculture, U.of.k.

3 TABLE OF CONTENTS Title Page #

Dedication Acknowledgment Contents I List of tables III List of figures V English abstract VI Arabic abstract VII

1. Introduction 1

2. Literature review 4 2.1 Plant and fruit 4 2.1.1 Scientific and common names of Gudeim plant 4 2.2 Agro ecology 4 2.3 General description and uses 4 2.4 Fruit and Juice 6 2.4.1 Grewia species 6 2.4.2 Fruit species and juice name 8 2.4.3 Juice extraction 8 2.4.3.1 Water extracted fruit juice 8 2.4.3.2 Quality of extraction water 8 2.4.3.3 Juice production 9 2.4.4 Juices of similar extraction steps to Gudeim juice 11 2.4.4.1 Soya bean drink 11 2.4.4.2 Tomato juice 12 2.4.4.3 Cranberry juice 12 2.4.4.4 Red cherry juice 13 2.5 Juice yield 13 2.6 Juice packaging 13 2.6.1 Package types 14 2.7 Juice characteristics 15 2.7.1 Chemical and physical characteristics 15 2.7.1.1 Approximate composition of fruit and juice 16 2.7.1.2 Soluble solids and acid content 18 2.7.1.3 Acidity and pH 18 2.7.1.4 Crude fibers 19 2.7.1.5 Pectin and viscosity 19 2.7.1.6 Vitamins and mineral 20 2.7.2 Color 20 2.8 Microbiology of juices 22 2.9 Organoleptic characteristics 26 2.10 Juice shelf life 27 2.11 Juice consumption in Sudan 28

4 3. Materials and Methods 30 3.1 Materials 30 3.1.1 Gudeim fruit 30 3.1.2 Water for extraction 30 3.1.3 Packages 30 3.2 Methods 30 3.2.1 Juice extraction 31 3.2.2 Yield calculation 31 3.2.3 Physicochemical assessment 35 3.2.3.1Color measurement 35 3.2.3.2 Viscosity measurement 35 3.2.3.3 Soluble solids (ºBrix) 35 3.2.3.4 pH measurement 35 3.2.3.5 Total acidity 36 3.2.3.6 Stability 36 3.2.4. Proximate composition 36 3.2.5 Minerals content 36 3.2.6 Sugars content 37 3.2.7 Microbiological analysis 37 3.2.7.1 Total bacterial and fungi counts 37 3.2.7.2 Total Coliform counts 37 3.2.8 Sensory evaluation 37 3.2.9 Storage life evaluation 38 3.2.10 Experimental Design and Statistical analysis 38

4. Results and Discussion 39 4.1 Quality of water for juice extraction 39 4.2 Fruit proportions 39 4.3 Juice yield 42 4.4 Proximate analysis 45 4.5 Sugar content 45 4.6 Visual features of Gudeim juice 51 4.7 Juice stability 54 4.8 Physicochemical properties 54 4.9 Color evaluation 67 4.10 Microbiological analysis 75 4.11 Sensory evaluation 79 4.12 Shelf life 81

5. Conclusions and Recommendations 87 5.1 Conclusions 87 5.2 Recommendations

6. References 89

5 LIST OF TABLES Table # Page #

Table [1] : Examples of fruit juice pH and risk organisms 25

Table [2] : Volume, growth rate and per capita consumption of ready to drink juice in Sudan 29

Table[3] : Properties of water used in Gudeim juice extraction 40

Table[4] : Gudeim fruit parts proportions before and after washing 41

Table[5] : Effect of extraction method and extraction ratio on the yield of Gudeim juice 44

Table [6] : Proximate composition of Grewia tenax juice and Fruit 46

Table [7] : Typical chemical composition of some fruits (edible portion) compared to that of Gudeim 47

Table [8] : Minerals contents of Gudeim fruit and juice and the effects of extraction temperature on the minerals content of Gudeim juice (ppm) 49

Table [9] : Sugar contents of Gudeim flesh and juice (%) 50

Table [10] : Stability tests results for a semi-clarified Gudeim juice 57

Table[11] : Natural fruit juice Brix and relative density in comparison with Gudeim juice 58

Table [12] : Effect of extraction temperature on certain Physico- chemical Properties of Gudeim juice 60

Table [13] : Effect of extraction method on certain physico- Chemical properties of Gudeim juice 61

Table [14] : Effects of extraction method and temperature on certain physicochemical properties of Gudeim juice 62

Table [15] : Effect of storage period on certain physicochemical properties Of Gudeim juice 63

Table [16] : Effect of package type on certain physicochemical properties of Gudeim juice 65

III

6 Table [17] : Interactive effects of extraction method and storage period on the total soluble solids (Brix), pH and acidity of Gudeim juice 66

Table [18] : A comparison between the physicochemical properties and yield of Gudeim juice and that of some tropical fruits juices 68

Table [19] : Effects of extraction method on the hunter color values of Gudeim Juice 69

Table [20] : Effects of storage period on the hunter color values of Gudeim Juice 71

Table [21] : Interactive effects of storage period and extraction temperature on the hunter color values of Gudeim juice 72

Table [22] : Interactive effects of storage period and method of extraction on the Saturation index and Hue angle of Gudeim juice 74

Table [23] : Comparison of Gudeim juice Hunter color values with that of Mango and Gamardeen juices 76

Table [24] : Effects of extraction temperature and storage period on certain micro-biological properties of Gudeim

juice(log10 CFU/ml) 77

Table [25] : Effects of extraction method and storage period on Sensory properties of Gudeim juice 80

Table [26] : Effect of extraction temperature and storage period on certain physicochemical properties and sensorial acceptability of Gudeim juice 82

Table [27] : Summary of observations on refrigerated Gudeim juice after21 days of storage in four types of packages 84

7 LIST OF FIGURES

Figure # Page #

Fig [1]: Gudeim fruit setting in twos and fours 7

Fig [2]: The protocol of preparing Gudeim fruits for juice extraction 32

Fig [3]: The soaking step in Gudeim juice production 33

Fig [4]: Flow diagram for Gudeim juice extraction, packaging and storage 34

Fig [5]: Gudeim waste after the juice extraction by hand pressing 43

Fig [6]: Color appearance of Gudeim juice from cold and hot extraction immediately after extraction 52

Fig [7]: Gudeim juice from cold (right picture) and hot (left) extraction after 7 days of storage at about 3 ºC 53

Fig [8]: Separation of Gudeim juice from cold and hot hand pressed (a) and cold and hot blended (b) after allowed to stand for 24 hours 55

Fig [9]: Depth of separation layer of Gudeim juice from hot and hand pressed HH- (left) and hot blended (right) after allowed to stand for 24 hrs. 56

Fig [10]: Bottled Gudeim juice immediately after cold (blue cap) or hot (red cap) extraction 85

Fig [11]: Evidence of blowing (arrow) in cold extracted Gudeim juice after 28 days of refrigerated storage 86

8 ABSTRACT A 2×2×4 factorial experiment in a completely randomize design was utilized to study the effects of extraction temperature [cold (room) and hot (65ºC)], extraction methods (hand pressing and blending) and 4 types of packages (GB, PB, PC and TT carton) on yield and physicochemical, microbiological and storage life of Gudeim (Grewia Tenax) juice stored refrigerated for up to 28 days. Irrespective of the extraction temperature or extraction method, a 1:4 ratio (Gudeim fruit: water) gave a Juice yield of about 76 %. Fresh Gudeim juice has a pH around 4.00, an acid content of 0.25 – 0.29 %, total soluble solids of 9.36 ºBrix , total solids of 10.15% , viscosity of 11.4 sec. and specific gravity of 1.055 . The chemical composition revealed that glucose and fructose are the two main sugars in Gudeim fruit and juice with fructose being the predominant sugar. Cold extracted Gudeim juice contained substantial amount of iron ( 6.73 ppm) and potassium (1.42 g/kg) however hot extraction resulted in a substantial decrease in mineral contents of Gudeim juice. The chemical composition of Gudeim fruit resembles that of most fruits except that it has higher protein and ash contents. The physicochemical properties of hand pressed juice particularly ºBrix and pH were significantly higher than those of blended juice but had significantly lower acidity. Effect of storage period on total soluble solids was noticeable after 14 days while pH and acidity decreased and increased respectively with the increase in storage period. Package type had only slight effects on the physicochemical properties of Gudeim juice. All Hunter color values showed a significant change with storage period. Hunter L* value of cold extracted juice was higher than that of hot extracted juice. Initially cold extracted juice had higher total plate count (TPC) and Coliform however hot extracted juice had higher yeast and moulds count, the trend continued throughout the storage period tested. The storage life of semi-clarified unpasteurized Gudeim juice was about 14 days. VI

9 اﻟﻤﻠﺨّﺺ

اﺳﺘﺨﺪﻣﺖ ﺗﺠﺮﺑﺔ ﻋﺎﻣﻠﻴﺔ (2×2×4 ) ﻓﻲ ﺗﺼﻤﻴﻢ ﺗﺎم اﻟﻌﺸﻮاﺋﻴﺔ ﻟ ﺪِ ر ا ﺳَ ﺔ ﺗﺄﺛﻴﺮ د ر ﺟ ﺔِ ﺣﺮارة اﻹﺳﺘﺨﻼص [ ﺑﺎرد( درﺟﺔ ﺣﺮارة اﻟﻐﺮﻓﺔ) وﺣﺎر (º65س) ] ، ﻃﺮق اﻹﺳﺘﺨﻼص ( اﻟﻌﺼﺮ اﻟﻴﺪوي واﻟﺨﻠﻂ اﻻﻟﻲ) و4 أ ﻧ ﻮ ا عِ ﻣِ ﻦْ اﻟﻌﺒﻮات( ﻗﺎرورة زﺟﺎﺟﻴﺔ،ﻗﺎرورة ﺑﻼﺳﺘﻴﻜﻴﺔ، آﻮب ﺑﻼﺳﺘﻴﻚ و ﻋﺒﻮة آﺮﺗﻮﻧﻴﺔ) ﻋﻠﻰ ﻋﺎﺋﺪ ﻋﺼﻴﺮ اﻟﻘﻀﻴﻢ و اﻟﺨﺼﺎﺋﺺ اﻟﻔﻴﺰﻳﻮآﻴﻤﻴﺎﺋﻴﺔ و اﻟﻤﻴﻜﺮوﺑﻴﻮﻟﻮﺟﻴﺔ و ا ﻟﻌﻤﺮ اﻟﺘﺨﺰﻳﻨﻲ ﻟﻠﻌﺼﻴﺮ اﻟﺬي ﺧَﺰن ﻣُ ﺒَ ﺮﱠ د اً ﻟﻤﺪة أﻗﺼﺎهﺎ 28 ﻳﻮ ﻣﺎ . ﺑﻐﺾ اﻟﻨّﻈﺮ ﻋﻦ د ر ﺟ ﺔِ ﺣﺮارة اﻹﺳﺘﺨﻼص أَو ﻃ ﺮ ﻳ ﻘ ﺔَ اﻹﺳﺘﺨﻼص ،ﻓﺎن ﻧﺴﺒﺔ 4:1 (ﻗﻀﻴﻢ: ﻣﺎء) أ ﻋ ﻄ ﺖْ ﻋﺎﺋﺪ ﻋ ﺼ ﻴ ﺮِ ﻓﻲ ﺣﺪود 76 %. آﺎن ﻟﻌﺼﻴﺮ اﻟﻘﻀﻴﻢ اﻟﻄﺎزج أس هﻴﺪروﺟﻴﻨﻲ (pH ) ﺣﻮاﻟﻲ 4.00، ﻧﺴﺒﺔ ﺣﻤﺾ 0.25 - 0.29 %، ﻣﻮاد ﺻ ﻠ ﺒ ﺔَ ﻗﺎﺑﻠﺔ ﻟ ﻠ ﺬ و ﺑ ﺎ نَ º9.36 ﺑﺮآﺲ ، ﻣﻮاد ﺻ ﻠ ﺒ ﺔَ آﻠﻴﺔ 10.15 %، ﻟﺰوﺟﺔ 11.4 ﺛﺎﻧﻴﺔ(زﻣﻦ اﻧﺴﻴﺎب) ووزن ﻧﻮﻋﻲ 1.055. آَ ﺸ ﻒَ ا ﻟ ﺘ ﺮ آ ﻴ ﺐَ اﻟﻜﻴﻤﻴﺎﺋﻲَ أ نّ اﻟﺠﻠﻮآﻮزِ و اﻟﻔﺮآﺘﻮزهﻲ ا ﻟ ﺴ ﻜّ ﺮ ﻳ ﺎ تَ اﻟﺮﺋﻴﺴﻴﺔَ ﻓﻲ ﻟ ﺐِ و ﻋ ﺼ ﻴ ﺮِ اﻟﻘﻀﻴﻢ ﻋﻠﻤﺎ أن اﻟﻔﺮآﺘﻮزهﻮ ا ﻟ ﺴُ ﻜّ ﺮَ ا ﻟ ﺴ ﺎ ﺋ ﺪَ. اﺣﺘﻮي ﻋ ﺼ ﻴ ﺮِ اﻟﻘﻀﻴﻢ اﻟﻤﺴﺘﺨﻠﺺ ﻋﻠﻲ اﻟﺒﺎرد ﻋﻠﻲ ﻧﺴﺒﺔ ﺟﻴﺪة ﻣﻦ اﻟﺤﺪﻳﺪ ( 6.73 ﺟﺰء ﻣﻦ اﻟﻤﻠﻴﻮن ) و اﻟﺒﻮﺗﺎﺳﻴﻮم ( 1.42 ﺟﻢ /آﺠﻢ ) ﻏﻴﺮ أن اﻻﺳﺘﺨﻼص اﻟﺤﺎر أدّى إﻟﻰ اﻧﺨﻔﺎض آﺒﻴﺮ ﻓﻲ ﻣﺤﺘﻮي اﻟﻌﻨﺎﺻﺮ اﻟﻤﻌﺪﻧﻴﺔِ ﻓﻲ ﻋ ﺼ ﻴ ﺮِ اﻟﻨﺎﺗﺞ. ﻳَﺸْﺒﻪُ ا ﻟ ﺘ ﺮ آ ﻴ ﺐُ اﻟﻜﻴﻤﻴﺎﺋﻲُ ﻟﻔﺎآﻬﺔِ اﻟﻘﻀﻴﻢ ﻧﻈﻴﺮﻩ ﻓﻲ ﻣﻌﻈﻢ اﻟﻔﻮاآﻪ اﻷﺧﺮيِ ﻣﺎﻋﺪا أن ﻣﺤﺘﻮاﻩ ﻣﻦ اﻟ ﺒﺮوﺗﻴﻦُ و اﻟﺮﻣﺎدأﻋﻠﻰ ﻣﻦ ﻧﻈﻴﺮﻩ ﻓﻲ اﻟﻔﻮاآﻪ اﻷﺧﺮي . اﺣﺘﻮي اﻟ ﻌﺼﻴﺮ اﻟﻤﻨﺘﺞ ﺑﺎﻟﻌﺼﺮ اﻟﻴﺪوي ﻋﻠﻲ ﺧﺼﺎﺋﺺ ﻓﻴﺰﻳﻮآﻴﻤﻴﺎﺋﻴﺔ ﺧﺼﻮﺻﺎً اﻟﻤﻮاد اﻟﺼﻠﺒﺔ اﻟﺬاﺋﺒﺔ ( درﺟﺔ ﺑﺮ آﺲ) واﻷس اﻟﻬﻴﺪروﺟﻴﻨﻲ (4.1) أﻋﻠﻰ ﻣﻦ اﻟﻌﺼﻴﺮ اﻟﻤﻨﺘﺞ ﺑﺎﻟﺨﻠﻂ اﻵﻟﻲ ﻏﻴﺮ أﻧﻪ اﺣﺘﻮي ﻋﻠﻲ ﺣﻤﻮﺿﺔ أﻗﻞ . آﺎن ﻟ ﻔ ﺘ ﺮ ةِ ا ﻟ ﺨ ﺰ نِ ﺗﺄﺛﻴﺮ واﺿﺢ ﻋﻠﻰ اﻟﻤﻮاد ا ﻟ ﺼ ﻠ ﺒ ﺔِ اﻟﻘﺎﺑﻠﺔ ﻟ ﻠ ﺬ و ﺑ ﺎ نِ ﺑﻌﺪ 14 ﻳ ﻮ مِ ﺑﻴﻨﻤﺎ اﻧﺨﻔﺾ و ارﺗﻔﻊ اﻷس اﻟﻬﻴﺪروﺟﻴﻨﻲ (pH) وﻧﺴﺒﺔ اﻟﺤﻤﻮﺿﺔ ﻋﻠﻰ اﻟﺘﻮاﻟﻲ ﺑﺎزدﻳﺎدِ ﻓ ﺘ ﺮ ةِ اﻟﺘﺨﺰ ﻳ ﻦِِ. آﺎن ﻟﻨﻮع اﻟﻌﺒﻮة ﺗﺄﺛﻴﺮﻃﻔﻴﻒ ﻋﻠﻲ اﻟﺨﺼﺎﺋﺺ اﻟﻔﻴﺰﻳﻮآﻴﻤﻴﺎﺋﻴﺔ ﻟﻌﺼﻴﺮِ اﻟﻘﻀﻴﻢ . ﺗﻐﻴﺮت آُﻞّ ﻗِﻴَﻢ هﻨﺘﺮ ﻣﻌﻨﻮﻳﺎ ﻣﻊ ازدﻳﺎد ﻓﺘﺮةِ اﻟﺘﺨﺰﻳ ﻦِ. آﺎﻧﺖ ﻗﻴﻢ هﻨﺘﺮ *L ﻟ ﻌ ﺼ ﻴ ﺮِ اﻟﻘﻀﻴﻢ اﻟﻤﺴﺘﺨﻠﺺ ﻋﻠﻲ ا ﻟ ﺒ ﺎ ر دِ ( 52.17)

VII10 أﻋﻠﻰ ﻣِﻦْ ﺗﻠﻚ اﻟﻨﺎﺗﺠﺔ ﻣِﻦْ اﻟﻌﺼﻴﺮِ اﻟﻤ ﺴﺘﺨﻠﺺ ﻋﻠﻲ اﻟﺤﺎرِ( 49.81). ﺑﻌﺪ اﻻﺳﺘﺨﻼص ﻣﺒﺎﺷﺮة آﺎن اﻟﻌﺪ اﻟﻜﻠﻲ ﻟﻠﺒﻜﺘﺮﻳﺎ و ﺑﻜﺘﺮﻳﺎ اﻟﻘﻮﻟﻮن ﻟ ﻌ ﺼ ﻴ ﺮِ اﻟﻘﻀﻴﻢ اﻟﻤﺴﺘﺨﻠﺺ ﻋﻠﻲ ا ﻟ ﺒ ﺎ ر دِ أﻋﻠﻰ ﻣﻤﺎ هﻮ ﻣﻮﺟﻮد ﻓﻲ ﻋﺼﻴﺮ اﻟﻘﻀﻴﻢ اﻟﻤﺴﺘﺨﻠﺺ ﻋﻠﻲ اﻟﺤﺎر ﻏﻴﺮ أن اﻷﺧﻴﺮ اﺣﺘﻮي ﻋﻠﻲ ﺧﻤﺎﺋﺮ و ﻓﻄﺮﻳﺎت أﻋﻠﻰ و ﻗﺪ آﺎن هﺬا هﻮ اﻻﺗﺠﺎﻩ اﻟﻐﺎﻟﺐ ﺣﺘﻲ ﻧﻬﺎﻳﺔ ﻓﺘﺮة اﻟﺘﺨﺰﻳﻦ اﻟﻤ ﺨﺘﺒﺮة. ان اﻟﻌﻤﺮ اﻟﺘﺨﺰﻳﻨﻲ ﻟﻌﺼﻴﺮ اﻟﻘﻀﻴﻢ ﻏﻴﺮ اﻟﻤُﺒَﺴﺘَﺮ وﺷﺒﻪ اﻟﺮاﺋﻖ ﻳﺴﺎوي ﺗﻘﺮﻳﺒﺎً 14 ﻳﻮﻣﺎ.

VII

1. INTRODUCTION

Gudeim (Grewia tenax) from the family Tiliaceae is a tropical bushy tree 2-7 m high. Its flowers are yellow, purple or white, solitary or in twos or fours, in a terminal head about 5cm long, with central flowers opening first. The fruit is in four parts, each rounded and fleshy about 5-10 mm across. Fruits are edible. Fruits color change gradually from green to bright red when ripe. The soil types favored by the plant in Sudan are rocky, sandy depressions, dunes, clay, and temporary pools. In Ethiopia: semi-arid woodland in dry and moist mid-and lowlands (1000-2300m). In India: rocky, gravelly piedmont plains and hills. The Fruit is eaten fresh or dried for later consumption and the seeds are edible. In Sudan several savanna trees yield edible fruits e.g Aradaib (Tamarindus indica), ‘Dom’ (Hyphaene thebaica), ‘Gunguleiz’ (Adansonia digitata), ‘Lalob’ (Balanites aegyptiaca) and ‘Nabag’ (Ziziphus spina-chrisiti). These fruits are extensively used as a diet for rural people. They provide vitamins, proteins and minerals and ensure food and nutritional security especially during periods of climatic stress as well as nutritional and financial deficiency. The fruits have an exceedingly wide range of uses, i.e. food source, beverages and medicinal uses. Gudeim juice traditionally prepared at home by cleaning the fruits, overnight soaking, pressing or blending, sieving, and sweetening. Porridge, called Nesha, is prepared from the juice, by addition of custard and flour. Nesha is given to mothers to improve their health and lactation. The market for commercially packaged juice products in Sudan has remained small due to the fact that consumers are used to fresh fruit grown locally (e.g. Lemon, Orange, Grapefruit, Guava and Mango) ,from which they squeeze fresh juices at home or purchase it by the

12 cup from juice stalls. At these juices stalls, juice extracted by diffusion from fruits of Sudan savanna trees (e.g. Aradaib, Gunguleiz and Gudeim) were found among the fresh squeezed juices of the above mentioned locally grown fruits. So nowadays Gudeim juice became of some market value; it is prepared as a market juice product and sold among the other chilled unpasteurized fruit juices and drinks to different consumers. The people believe that it is a simple safeguard against iron-deficiency anemia. Hence Interest in the Gudeim fruit and juice chemical composition has intensified because of the increased awareness of the possible nutritional values of its constituents in addition to its economical value. From the microbiological point of view the chilled unpasteurized juices are more susceptible to microbial deterioration than juices pasteurized under time/temperature regimens. Unpasteurised high acid juices rely only upon low pH, cold temperature scrupulous sanitation and good manufacturing practice (GMP’s) to inhibit microbial contamination and proliferation during handling, storage anddistribution. Yeast predominates in spoilage of acid fruit products because of their high acid tolerance and the ability of many of them to grow anaerobically. Yeasts, molds, and lactic acid bacteria have been implicated in spoilage of fruit juices. Fruit juices are widely consumed in ever-increasing quantities and are very important commodities in the trade of most countries. The Institute for Monetary and Economic Studies (IMES, UK) performed a research report on the Sudan market consumption of ready to drink juice products, and reported that the consumption increased from 0.2 million liter in the year 1995 to 1.3 million liter in the year 2000, and expected to grow at a rate of 12% through the following five years. In comparison with the neighboring countries if we look to the Saudi Arabia market we find that the IMES consulting limited reported that

13 consumption of fruit juice and drinks in 1992-1996 increased from 236 million liters in the year 1992 to 321 million liters in the year 1996 and forecasted to reach 392 million liters in the year 2000. Hence From the marketing point of view, with the development occurring in the juice market of Sudan, the consumption of Gudeim juice will have the chance to grow among the other juices and its yield evaluation will help to estimate the revenue from it as a commercial commodity.

Objectives of the study 1- To determine the yield of Gudeim juice. 2- To study the physicochemical properties of Gudeim juice. 3- To study the storage life of Gudeim juice.

14 2. LITERATURE REVIEW 2.1 Plant and Fruit

2.1.1 Scientific and Common Names of Gudeim Plant

Campin (2002), Westermier and Kraus (1999), Bekele-Tesemma (1993) and Freedman (1998) reported the scientific name Grewia tenax (Forssk) Fiori under the family Tiliaceae. Sudanese investigators (Eltohami 1998, Abdelmuti 1991, Elsiddig 2002) agreed on the scientific name i.e. Grewia tenax (Forssk) Fiori, however each one of them reported a slightly different local name i.e. Gaddem (abdelmuti 1991), Godeim (Eltohami 1998) and Gudeim (Elsidig 2002). Since Gudeim is most commonly used name in Sudan we will use it throughout this text. Common name in Ethiopia is (Fo) and in India (Gangera or Gangeran).

2.2 Agro Ecology

Gudeim in Sudan is found rocky, sandy depressions, dunes, clay, and temporary pools (Abdelmuti, 1991).Where as in Ethiopia is found in semi- arid woodland in dry and moist mid – and lowlands (Bekele-Tesemma, 1993). In India it is found in Rocky, gravelly piedmont plains and hills (Gupta, 1998 ; Sastri, 1956 ). 2.3 General Description and uses According to Bekele-Tesemma, (1993) Grewia plant propagation is by seedling. Desroseir (1977) reported that fruits are defined as ripened ovaries of a flower; the edible portion is usually the fleshy covering over the seeds. Tree fruits are grouped into deciduous (shed their leaves in the fall) and evergreen (shed their leaves in the spring).

15 Gebauer et al., (2002) described Grewia tenax as a deciduous shrub, up to 2-meter height; they considered it as one of several savanna trees that yield edible fruits. These fruits are widely used in rural people diet. They provide their consumers with useful nutrients like vitamins, proteins and minerals; hence they ensure some sort of food security especially during periods of climatic stress.

Elsiddig (2002) reported that Gudeim tree is a tropical bushy tree, up to 2m high, with rounded, pendulous fruit, 5-10 mm across. Fruit change gradually from green to red when quite ripe. Fruits are eaten fresh or dried for later consumption. The firm, fleshy layer surrounding the stone is edible and is relished out-of-hand by children and adults, alike. Fruit Juice is regarded a great thirst- quencher, especially during the hot months from March to July. Also thin porridge (Nesha), prepared by boiling fruit pulp and millet flour is given to pregnant and lactating women to improve their health and milk production. The wood is hard and durable.

Eltohami (1998) included the Gudeim in the list of the medicinal and aromatic plants of Sudan.

Abdelmuti (1991) reported that Gudeim Fruit is eaten fresh or dried for later consumption. Soaking the fruit overnight, hand pressing, sieving, and sweetening prepare a drink. Porridge, called Nesha, is also prepared from this drink, by the addition of custard and flour. Nesha is given to mothers to improve their health and lactation.

Bekele-Tesemma, (1993) considered Grewia tenax as one of Ethiopia famine foods and described it as a shrub or small tree up to 7m. The flowers are yellow, purple or white, solitary or in twos or

16 fours, in a terminal head about 5cm long, the central flowers opening first, many stamens in the center. The fruit is in twos or fours (Fig.1), each rounded and fleshy about 5mm across. The ripe fruits are edible and are eaten raw. The fruits are sweet and may be eaten either as a whole or chewed and only the sweet juice is swallowed. If large amounts of seeds are ingested they may cause severe constipation. The fruits are always collected and consumed between September and April, and everybody enjoys its taste also in good times. Grewia tenax – ferruginea can give fruits three times a year, provided there is sufficient rain. At the time of food shortage Gudeim can fill the food gap.

Grewia tenax is regarded as one of India famine foods and that it is an acrid orange fruits usually eaten raw Freedman (1998). 2.4 Fruit and Juice

2.4.1 Grewia species

Freedman (1998) reported the following species of the genus Grewia among the famine foods of the family Tiliaceae: (Grewia asiatic, Grewia microcos, Grewia oppositifolia, Grewia populifolia, Grewia pilosa, Grewia tiliaefolia, Grewia villosa).

Morton (1987) reported on Grewia asiatic (Vernacular name: Falsa). Fruits are small almost round drupes like blueberry and purple, crimson or cherry red in color when ripe. Phalsa is the most used vernacular name in India where there are a number of dialectical names. The plant is called falsa in Pakistan.

Fig. 1: Gudeim fruit setting in Twos (upper) and Fours ( lower)

19 2.4.2 Fruit Species and Juice Name

The species indicated as the botanical name shall be used in the preparation of fruit juices and fruit nectars bearing the product name of the applicable fruit. For fruits not included in the list of the International Codex Alimentarius Commission, the corrected botanical or common name shall apply (Codex Stan 164, 1989). For fruit juice extracted from dried fruit and other juices, which need to be extracted with water, the name of the product shall be “______juice” or “juice of______”. Hence we will use the name Gudeim Juice through out this text.

2.4.3 Juice Extraction 2.4.3.1 Water extracted fruit Juice Water extracted fruit juice is the product obtained during the primary extraction of pulpy whole fruit or dehydrated whole fruit by diffusion with water (Codex stan 164, 1989). The UK fruit juice and nectars regulations 1977 stated that fruit juice means food consisting of fermentable but unfermented juice which is obtained from fruit other than apricots, citrus fruits, grapes, peaches, pears or pineapples by diffusion process and intended to be used in the preparation of the concentrated fruit juice. 2.4.3.2 Quality of Extraction Water Bockelmann and Bockelmann (1998) reported that the quality of water used for juice extraction is of primary importance. It should be of potable water quality. Ashurst et al. (1998) stated that water for juice extraction should be free from high levels of elements and mineral salts, objectionable tastes & odors, and Organic material. It should also be clear and colorless, free from dissolved oxygen, and sterile, i.e. free from microorganisms.

20 2.4.3.3 Juice Production Many fruits are eaten fresh but high juice demand and a value added potential have increased interest in producing juice (Golaszewiski et al., 1998). The suitability of fruits for juice production is greatly affected by cultivars, maturity, and growing conditions (Robert, 1974). Westermeier and Kraus (1999) assed the ability of Gudeim beans for juice production and determined its chemical composition. They used an extraction ratio of 1 : 4 (Gudeim beans : water ) and soaking time of about two hours then the fruits are pressed and stirred and the whole mass is filtered through a filter cloth and pressed. They obtained a yield of 75% deep orange juice which tastes good and fruity; and it can stay in the refrigerator for a long time without loosing quality. The juice had a pH of 4.5, total soluble solids of 8.4º Brix and acid content of about 2.5g/L . Such an acid content may explain the ability of Gudeim juice to stay preserved for a long time. Ashurst et al. (1998) reported that juice processing technology in general could be in the following steps: fruits are collected, sorted and washed, and then subjected to a mechanical compression that is relevant to the fruit concerned. Some fruit types (e.g. pomes fruits such as apples and pears) requires mechanical treatment (milling) coupled with a biochemical process (involving enzymes) to breakdown the cellular structure and obtain best yields. Additionally, and as mentioned in the juice definitions, a diffusion or extraction process can be used to obtain best yields from certain fruits. If juice is not to be sold as ‘not from concentrate’, it is usually screened and pasteurized immediately after pressing, an operation with two main objectives; The first is to control growth of spoilage microorganisms that live on the fruit surface (mainly yeasts and moulds). The second is to destroy the pectolytic enzymes that occur naturally in fruit, which would otherwise breakdown the cloudy nature of the juice. If, however, a clear juice is

21 required (e.g. apple or raspberry), enzymes may be added to accelerate this natural process. Detailed operations for obtaining juices vary considerably depending upon the types and characteristics of the fruit concerned. However, almost without exception there are three separate stages of Juice extraction, finishing (separation of juice from fruit pulp or fruit parts) and some kind of stabilization (often pasteurization or heat treatment in some form). Norman (1973) stated that the fruit is normally washed and screened to remove foreign bodies followed by crushing or squeezing process using grinders, disintegrators, or reamers usually carries out juice extraction. To clarify the juice it is necessary to treat the juice beyond simple filtration or centrifugation since the fine pulp, which makes filtering or centrifuging, more effective. Orange juice on the other hand is more acceptable if it retains a slight cloud of suspended pulp and so this is not removed. The juice pressed contains small quantities of suspended pulp, which is often removed. Fine filters may do this, but these have a tendency to Clog, it is common to use high-speed centrifuges, which separate the juice from the pulp according to their differences in density. Robert (1974) reported that finishing the juices was usually carried out by means of screening device, usually with a conical or cylindrical screw forcing the juice components through fine screen. Usually this phase is followed by a heat or enzymes treatment, or more recently, ion exchange or dialysis to protect or stabilize flavors, cloud, and other desirable physical factors. Ashurst et al. (1998) reported that juice was separated using either centrifuges or fruit presses. Bockelmann and Bockelmann (1998) claimed that since heat treatment may induce flavor change and loss of vitamin C, the heat treatment should be kept as low as possible. Enzymes especially pectinase need to be inactivated and this

22 requires a certain minimum heat temperature. Warring (1981) stated that a filter is basically a device for separating one substance from another-hence filtration is basically a process of separation. Filters are used also for separating contaminants. 2.4.4Juices of similar extraction steps to Gudeim Juice

2.4.4.1 Soya bean Drink

Bockelmann and Bockelmann (1998) reported on the step of cleaning fruits for Soya bean drink, that commercial Soya beans contain microorganisms, dirt, and dust on their surfaces. Removal of foreign materials such as straw, stones, metals and weeds is as important as the removal of damaged Soya beans. It is an advantage to wash the Soya beans before they are processed. The beans swell to a very high degree when immersed in water. Washing should be done at ambient temperature (~ 30 ºC) for a minimum of two hours, but not for more than five hours. Soya bean drinks can be made from either soaked or dry beans. Soya beans can be soaked in about three times their weight of water. Typically, the soaking time is 8-10 hours at 20 ◦C. the soaking times are shorter at higher temperatures. At soaking temperatures above 45 ºC, the total solids content decrease from 60% to 55%. There is also small decrease in the recovery of fat and protein.

Dehulled Soya beans reach full hydration much faster than whole Soya beans: only 2-3 hours are required at 30 ◦C or 1 hour at 50 ◦C, compared to 7 hours at 30 ◦C, and 3-4 hours at 50 ◦C for whole beans. Filtering the insoluble Soya residues are removed from the slurry by a decanter centrifuge to improve flavor, texture and to dispose oligosaccharides. Soya bean drink is cooked (100 ◦C for 8 to 22 minutes) in order to destroy microorganisms and to improve

23 flavor. One way to increase acceptance of Soya bean drinks is through an appropriate formulation that uses sweetening and a variety of flavoring agents.

2.4.4.2 Tomato juice Tomatoes are generally extracted by what may be thought of as preliminary finishing operation. After being inspected, trimmed and sorted, the fruit may be chopped into relatively large pieces without preheating (cold-break) or after preheating to about 160 ºF (hot-break). The tomato pieces are then pressed through a screen usually having 0.04. – 0.060 in. openings and this may be followed by a similar pressure-screening-finisher type operation using 0.020 – 0.025 in. openings. The finished material is used as tomato juice (Johnson and Peterson, 1974).

2.4.4.3 Cranberry Juice Johnson and Peterson (1974) reported that cranberry fruits might be crushed in a screw paddle type pressure extractor similar in principle to citrus juice finishers, or in some cases merely crushed by mixing with large paddles in holding tanks. They may be either hot or cold pressed and hydraulic pressure or, more usually carries out the pressing recently, by pressure filtration or continuous screw expeller presses. Most juices are pasteurized or stabilized at 175º – 190 ºF for few minutes. Norman (1973) reported that cranberry juice cocktail and similar cranberry juice products are among the most successful recently developed fruit products. Bockelmann and Bockelmann (1998) illustrated the production of cranberry juice according to the flow diagram below.

Cranberries Water Wash De-Watering Milling 24 Pasteurization & Filling Filtration Cranberry Pressing juice 2.4.4.4 Red cherry juice Red cherry juice may be prepared by either hot or cold pressing of fresh cherries or cold pressing of frozen cherries. Red cherries received at the processing plants are graded for defective, undersized, and immature fruit. Sorting is done to remove fruits that do not have typical red cherry color and those that showed blemishes as scar tissue, fungus and insect injury, hail injury, limb rubs, and excessive bruises. Sorted cherries are pitted with automatic pitting machine. The pits constitute 6.5 to 8.5 % of the weight of the cherries. A loss in the juice also occurs during the pitting operation and varies from 5-8% (Norman, 1973).

2.5 Juice Yield Braddock (1999) reported that as fruit matures the dry solids of the whole fruit and each component increases significantly. At the same time, the juice yield decreases substantially. Different types of fruit gave different juice yield. Saint-Hilaire and Struebs (1982) reported a juice yield in the range of 25 to 80 for different fruits as shown below: 1) pine apple:72% 2) mango: 31% 3) papaya: 70% 4) Guava: 25-30% 5) Cashew apple: 55-80% Anand (1960) extracted juice from Grewia asiatica but he did not report on the yield. Rather he concentrated on the preservation of the juice from yeast fermentation. 2.6 Juice Packaging Packaging is the key to the successful marketing of modern food products. It goes beyond eye appeal, convenience in size, and ease of opening (Pintauro, 1978). The packaging requirements depend on the kind of drink produced and the demand for shelf life connected

25 with processing. The shelf life increases if the package provides protection against light and oxygen (Bockelmann and Bockelmann, 1998). 2.6.1 Package types Ashurst et al. (1998) reported that traditionally most beverages were packed in glass, which has many attractive features. It is an excellent protective medium but its over-riding disadvantage is its weight and brittleness and cost (expensive compared to other types of packages) despite this, high volumes of soft drinks and juices remain in glass, some of it multi-trip packaging. The development of the board-polymer-aluminum package used to form in-line boxes, which are packed aseptically, has been perhaps the out standing packaging development for beverages. The pack provides an almost ideal combination of protection, minimal weight, and economic size. The third important packaging development area is plastic. Various plastics have been and continue to be used namely high and low- density polyethylene (HDPE, LDPE), polyvinyl chloride (PVC), and polystyrene (PS) and various barrier plastics. These can be formed into bottles of conventional shape or fed into machines producing form-fill-seal packages, typically cups. By far the most important plastic is polyethylene terphthalate (PET) which has properties that, apart from weight and brittleness, are surprisingly like those of glass. Perhaps the most exciting developments are yet to feature in fruit juices packaging. PET can be laminated with other plastics, such as nylon and EVOH (ethylene vinyl alcohol), to give extremely good barrier properties .Polyethylene naphthalate (PEN) may give a plastic bottle that can be pasteurized at high temperatures. The packaging type (bottles, cans, cartons, flexible pouches etc.) often determines the process available and sometimes the raw materials used. The formulator must select and establish that these together produce a product that has the required stability for the requested shelf life. Willige et al., (2002) reported that the absorption rate of flavor by the plastic materials: linear low-density polyethylene (LLDPE), oriented polypropylene (OPP), polycarbonate (PC), PET and PEN, increased considerably with temperature from 4 to 40 ºC. depending on storage temperature, total flavor absorption by the polyolefins (LLDPE and OPP) was 3 to 2400 times higher than by the polyesters (PC, PET, and PEN). Hence based on this flavor absorption factor, polyesters are preferred over polyolefins as packaging materials.

26 2.7 Juice Characteristics

2.7.1 Chemical and physical characteristics The quantitative analysis of fruits and their products may broadly be divided into proximate and ultimate analysis. The former gives useful information, particularly from the nutritional and biochemical point of view, while the latter refers to the determination of a particular element or a compound present in the material (Ranganna, 1977). Elsiddig (2002) reported that the Sudanese people consider Grewia Fruit a substitute for iron supplement, of the wide range of nutrients in the grewia fruit, the iron content has attracted most attention. Indeed the iron content to local Sudanese communities who know well that it is a simple safeguard against iron-deficiency anemia. It has on average, 2-3 times the Fe content of orange with up to 74 mg per 100 g fruit edible portion. The iron in the fruit juice, in particular, is noted for being much more easily assimilated than man-made forms of iron. The fruit is also rich in carbohydrates, minerals and vitamins, and low in fat and sodium. Fruit juice is important in human nutrition far beyond its use as a refreshing source of liquid. Many fruits contain a variety of minor ingredients, particularly vitamins and minerals, as well as carbohydrates, which are the predominant solid component. Although fruit contains small amounts of protein and fat, these are not important ingredients of juices (Ashurst, 1998).

2.7.1.1 Approximate Composition of Fruit and Juice Moisture, ash, acids, crude fat or ether extractives, protein, sugars and crude fiber are the major chemical compounds of fruits and fruit juices. Their sum (total) percentage subtracted from 100 represents primarily the amount of carbohydrates that includes starch, pectin,

27 gums, etc. in addition, all the errors in the determinations of all the other constituents are also reflected in the calculation of the carbohydrates other than sugars (Ranganna, 1977). Composition of fruits not only vary for a given kind in accordance with botanical variety, cultivation practices, and weather, but change with degree of maturity prior to harvest, and the condition of ripeness, which is progressive after harvest and is further influenced by storage conditions. Nevertheless, some generalizations can be made. Most fresh fruits are high in water, low in protein, and low in fat. In these cases water contents will generally be greater than 70% and frequently greater than 85%. Commonly protein contents will not be greater than 3.5% or fat contents greater than 0.5%. Exceptions exist in the case of dates and raisins, which are substantially, lower in moisture but cannot be considered fresh in the above sense. Fruits are important sources of both digestible and indigestible carbohydrates. The digestible carbohydrates are present largely in the forms of sugars and starches while the indigestible cellulosic materials provide roughage important to normal digestion. Chemical composition of Gudiem fruit (Sudan sample) was reported by (Abdelmuti, 1991)who found that a 6.3 % protein (dry); 0.4 % fat (dry); 8.1 5 crude fiber (dry); 4.5 % ash (dry); 15.1 % carbohydrate (dry); 1.60 % sucrose (dry); 21.0 % D-glucose (dry); 24.3% D-fructose (dry) and the following amino acids (g [16g N] -¹): 8.1(g) aspartic acid; 2.1(g) serine, 2.4(g) threonine; 6.2(g) glutamic acid; 2.0(g) lysine; 2.4(g) alanine 1.1(g) histidine ; 1.0(g) cysteine. Westermeier and Kraus (1999) reported that Grewia tenax juice contain different minerals, soluble solids, vitamin C in different proportions. The juice contained phosphorus, iron, manganese, magnesium, calcium, sodium, potassium, ascorbic acid, total soluble solids and total dry solids in the amounts of 81.5mg/kg, 7.02mg/kg,

28 0.66 mg/kg, 108 mg/kg, 73.7mg/kg, 61.6 mg/kg, 1610 mg/kg, 25mg/kg, 8.42 ºBrix/20 ºC and 8.43 % respectively. This juice had a pH of 4.50, a Titratable acidity of 2.60 mg/kg and a Relative Density 20/20 of 1.03375. Yadav (1999) reported that nutrient values per 100 grams phalsa fruits (Grewia asiatica) produced at fort valley, Georgia were as follows: calories (Kcal), 90.5; calories from fat (Kcal), 0.0; moisture (%), 76.3; fat (g), <0.1; protein (g), 1.57; carbohydrates (g), 21.1; dietary fiber (g), 5.53; ash (g), 1.1; calcium (mg), 136; phosphorus (mg), 24.2; iron (mg), 1.08; potassium (mg), 372; sodium (mg), 17.3; vitamin A (µg), 16.11; vitamin B, thiamin (mg), 0.02; vitamin B2, riboflavin (mg), 0.264; vitamin B3, niacin (mg), 0.825; vitamin C, ascorbic acid (mg), 4.385. Morton (1987), reported that analysis made on Grewia asiatica fruits in the Philippines show the following values: calories, 329 per lb (724 per kg); moisture, 81.13%; protein, 1.58%; fat, 1.82%; crude fiber, 1.77%; sugar, 10.27%.

2.7.1.2 Soluble solids and acid content

Braddock (1999) reported that the combined sensory properties of sweetness and tartness are most important to the fruit and juice quality of citrus. The sugars and acids are the most contributors to the soluble solids. Soluble solids content of the juice is determined based on specific gravity or refractive index of sucrose solutions and measured on a scale of ºBrix. Acids are determined by titrable acidity and expressed in grams per liter or as percent citric acid or other acid. The ºBrix/Acid ratio is an important sensory indicator useful in defining flavor attributes that depend on maturity and fruit ripeness. In most fruit juices sugars are a major component of the product. All

29 juices contain glucose, fructose, and some sucrose, but the individual proportions of these sugars will depend on the fruit variety and stage of maturity of the fruit from which the juice is extracted. One of the quickest and simplest way of assessing the soluble solids content in juices is to measure its refractive index using a refractometer, the assessment of refractometric solids content, generally referred to as °Brix. Wide range of high performance liquid chromatography (HPLC) methods has been used to determine sugars quantitatively and qualitatively. 2.7.1.3 Acidity and pH The normal method used to assess the juice acidity is by titration using sodium hydroxide. Traditionally phenolphthalein was used as an indicator to detect the end-point of the titration. Now, however, with the ready availability of pH meters, this is normally carried out to a final pH of 8.1, this has a major advantage as it allows the titration to be carried out automatically and avoids problems with colored products (Hammond, 1998). 2.7.1.4 Crude Fiber Crude fiber is the organic residues, which remains after the food sample has been treated under standardized conditions with petroleum spirit, boiling dilute sulphuric acid, boiling dilute sodium hydroxide solution and alcohol. The crude fiber consists of cellulose together with a little lignin (Ranganna, 1977). 2.7.1.5 Pectin and Viscosity The complex polymers of sugar acid derivatives include pectin and closely related substances. The cement-like substance found especially in the middle lamella, which helps hold plant cells to one another, is a water- insoluble pectic substance. Upon mild hydrolysis it yields water-soluble pectin and acid. Certain water-soluble substances also react with metal ions, particularly calcium, to form water-insoluble salts such as calcium pectate.

30 The various pectic substances may influence texture of fruits and vegetables in several ways. When vegetables or fruits are cooked some of the water- insoluble pectic substance is hydrolyzed into water-soluble pectin. This results in a degree of cell separation in the tissues and contributes to tenderness. Since many fruits and vegetables are somewhat acidic and contain sugars the soluble pectin tends to form colloidal suspensions, which will thicken the juice or pulp of these products. Fruits and vegetables also contain a natural enzyme (pectin methyl esterase) , which can further hydrolyze pectin to the point where the pectin loses much of its gel forming property. Products such as tomato juice or tomato paste will contain both pectin and pectin methyl esterase. If freshly prepared tomato juice or paste is allowed to stand, the original viscosity gradually decreases due to action of pectin methyl esterase on pectin gel. This can be prevented if the tomato products are quickly heated to a temperature of about 180 ºF to inactivate the pectin methyl esterase liberated from broken cells before it has a chance to hydrolyze the pectin. Such a treatment is commonly practiced in the manufacture of tomato paste and tomato juice products. This is known as the hot-break process and yields products of high viscosity. In contrast, where low viscosity products are desired no heat is used and enzyme activity is allowed to proceed. This is the cold-break process. After sufficient decrease in viscosity is achieved the product can be heat treated, as in canning, to preserve it for long-term storage. 2.7.1.6 Vitamins and Minerals Vitamin C is the most commonly used vitamin. It contributes to acidity otherwise has little initial flavor effect. It is easily broken down by oxygen thus stability is poor unless protected. In time it may cause browning of fruit juice, fading of color and off-flavors when added at high levels. The recommended daily allowance (RDA) is 60 mg for adults. Vitamin B complex has satisfactory stability and flavor profile in a soft drinks environment.

31 Calcium is usually added to help reduce osteoporosis and build strong teeth and bones. Iron, even at low levels, affects the flavor by imparting a metallic aftertaste. This is difficult to mask. Iron may adversely affect the stability of flavor and colors. Abdelmuti (1991) reported the following minerals contents of analyzed Gudeim fruit: Sulfur (dry), 00.10 %; potassium (dry), 00.08 %; magnesium (dry), 00.17 %; calcium (dry), 0.61 %; Na (dry), 0.01 %; K (dry), 1.45 %; zinc (mg/kg), 21; iron (mg/kg), 74; copper (mg/kg), 7; manganese (mg/kg), 10. 2.7.2 Color In addition to a great range of textures, much of interest that fruits add to our diets is due to their delightful and variable colors. The pigments and color precursors of fruits and vegetables occur for the most part in the cellular plastid inclusions such as the chloroplasts and the other chromoplasts, and to a lesser extent dissolved in fat droplets or water within the cell protoplast and vacuole. These pigments are classified into four major groups, which include the chlorophylls, carotenoids, anthocyanins, and anthoxanthins. Pigments belonging to the latter two groups also are referred to as flavonoids, and include the tannins (Norman, 1973). Natural plant-produced anthocyanin pigments, the substances that are largely responsible for intense red to blue colors in many foods, and related flavonoid phytochemicals are considered to be responsible for a range of unique and broad-spectrum health benefits. Hammond (1998) reported that fruit juice color might be assessed in a number of ways. If the juice is clear, it can simply be carried out by measuring the absorbance of the juice at one or more wavelength. The actual values chosen will depend on the particular color of the product. For a yellow product, such as apple juice, wavelengths of 465, 430 or

32 420 nm are often chosen to assess the color. These values can then be expressed in European brewing convention (EBC) units by multiplication by a factor of 25. The actual Brix value chosen to assess the color depends on the country; however, levels between 11 and 12 are often taken as the norm. If dealing with a red colored product the assessment is generally carried out at 520 nm. Absorbance values are sometimes also taken at 420 nm in red or black juices to assess the brownness of the product. The two-absorbance values are often used to express a colour ratio, which gives an indication of colour brownness: Color ratio = absorbance at 520 nm/absorbance at 420 nm. In cloudy products color assessment is more difficult. Removal of the particular material by filtration can be done in some cases. It has been known for a number of years that the simple approach of measurement of a product’s absorbance values at 420 or 520 nm does not fully address this issue because some products can have similar absorbance values at these wavelengths but will be perceived as very different by eye. One way that this has been addressed is by the use of tristimulus colour measurement. In this method the color is split into three separate primary components, which more closely match the way the eye perceives color. In this method the absorbance or reflectance of a product is measured at a range of wavelengths in the red, green and blue areas of the spectrum. The values are taken and the components X,Y,Z are calculated. These X,Y and Z values are then transformed to split the color up into three variables that address the color or hue (red/green, yellow/blue) of a product, the capacity of the color (how much light it reflects or absorbs) and finally the depth or intensity of the color (deep purple/pale purple). This three-dimensional space can be represented by either L, a, b or H, C, L values, which are different conventions used to describe a color in conceptionally a similar manner. In the L, a, b system, used by Hunter Lab, the color is defined in terms

33 of its lightness (L*) and two variables a* and b*, the latter two define the color hue and intensity. Red colors are situated in the +a direction; green has -a values. Yellow is in the +b direction and blue has -b values. The size of the value is an indication of the intensity of the color (i.e. the larger the size of the value, the more intense is the color). In the CIELAB 76 convention L defines the lightness, whereas H (hue angle) defines what the color is (red is situated at 0º, yellow at 90º, green at 180º and blue at 270º) and C (chroma) describes the intensity or depth of color. 2.8 Microbiology of juices Incidence of coliform types of bacteria is reported in fruit juices. Consumption of unpasteurised apple juice and cider had resulted in several episode of E.Coli 0157:H7. (Zhao et al. 1993;; Splittstoesser et al. 1996; Parish ,1997). Several factors have been cited for the contamination of apple juice with this pathogen among which are release of the organism from contaminated dropped apple with animal manure, contaminated water used in the extraction, food handlers combined with inadequate manufacturing practices. It is generally accepted that E.Coli 0157:H7 has low infective dose, ingestion of 10 to 100 cells can produce the disease also this organism is acid tolerant ( pH 3-4 ), hence is able to survive for extended period of time (Miller,1994; Splittstoesser et al. 1996). The main mycotoxin reported in fruit juices like apple, Guava, Orange, Grapefruit, tomato, pear, pineapple, strawberry, and cherries, include aflatoxins B1 and GI, Ochratoxin A, Patulin and alternariol ( Gokmen et al. 1998 and Acar et al. 1998). The maximum concentrations of these mycotoxins in fruit juices ranged from 0.03 to 733 ppb. The level of these toxins is affected by several factors e.g. fruit quality used in juice production, washing treatment prior to juice extraction, processing and

34 storage conditions (Jackson et al. 2003, Acar et al.,1998; Lovett et al., 1975). A characteristic shared by most fruit juices is high acidity. Accordingly a low pH in the range of 5.0 to less than 2.5 is considered the single most important factor in determining the types of microorganisms that can spoil fruit juices. While such low pH range inhibits most types of bacteria, fungi (yeast and moulds) tolerate such high acidity. Accordingly, yeast and moulds could be regarded as the principal spoilage microorganisms of fruit juices. For along time fruit juices were not recognized as vehicles of food borne illness because of their low pH and high organic acids levels. In the year 2001 FDA estimated 16000 to 48000 illnesses per year can be attributed to juices, most of it is due to consumption of unpasteurised juices. The types of bacteria that captured the attention of several investigators in fruit juices include E.Coli 0157:H7, Listeria monocytogens, Salmonella and Bacillus cereus (Collado et al. 2003). Vegetable and fruit juices most implicated include apple, orange, grape, carrot, lime and lemon. In recognition of the seriousness of the food-borne diseases that can be transmitted via unpasteurised fruit juices, different techniques were investigated to secure the safety of fruit juice. Davenport (1998) stated that the food microbiology is usually considered in two strategic areas: (i) Food-borne microbial diseases and the protection of the customer from these. (ii) Prevention of food spoilage due to the activity of microorganisms. Microorganisms associated with the soft drinks industry are usually confined to some yeast, acid-tolerant bacteria, a few non-acid- tolerant bacteria and a selection of moulds (table 1). Of these, the yeasts are the most important spoilage agents (Davenport, 1998). Bockelmann and Bockelmann (1998) reported that the main spoilage organisms in juices are yeast and moulds, though some (primarily lactobacillus and streptococcus) can multiply at low pH values i.e. below 4.6 and are those able to damage the product. Andres et. al. (2001) stated that from the microbiological point of view the chilled unpasteurised juices are more susceptible to microbial deterioration than juices pasteurized under time/temperature regimens. Unpasteurised high acid juices rely only upon low pH, cold temperature scrupulous sanitation and GMP’s to inhibit microbial contamination

35 and proliferation during handling, storage and distribution. Yeast predominates in spoilage of acid fruit products because of their high acid tolerance and the ability of many of them to grow anaerobically. Yeasts, molds, and lactic acid bacteria have been implicated in spoilage of fruit juices. Juices as fruit products or as ingredients have to be pasteurized or must receive an equivalent process that insures the production of juice free from pathogenic microorganisms as E.coli O157:H7, Salmonella and Criptosporidium. Previous washing of citrus fruits with chlorinated water is recommended to remove the soil from the fresh products. If washing is done properly, microbial population can be lowered.

The Grewia asiatica (phalsa) juice ferments so readily that sodium benzoate must be added as a preservative (Anand, 1960).

Table 1: Examples of fruit juice pH and risk organisms Fruit Approximate Risk organisms pH ranges Apples 2.9 – 3.91 Yeasts Grapes 3.20 – 4.51 Yeasts Oranges 3.20 – 4.30 Yeasts Raspberries 3.12 Yeasts Blackcurrants 2.48 – 3.60 Yeasts Pineapples 3.3 – 3.70 Yeast & bacteria Mangoes 3.95 – 4.50 Yeast & bacteria

36 Tomatoes 3.8- 4.8 Yeasts, bacteria and mould/bacteria Source: Ashurst et al. (1998).

2.9 Organoleptic Characteristics Flavor and odor of a soft drink or a fruit juice are important elements of the product that need to be closely monitored and controlled. Trained panelists generally carry this out. Sensory assessments should be carried out in a surrounding where the panelists can concentrate on their work without distractions (Hammond 1998). Braddock (1999) reported that a necessary requirement for processing fruit is that the juice has desirable sensory attributes. Sensory testing of juice flavor, color and other characteristics is widely practiced where juice is manufactured and packaged. The Florida citrus processor’ Association contracts one of the official taste panels with USDA. A unique feature is that this panel is a consumer preference panel composed of local citizens and processing plant personnel. The panel tests the juice on a nine-point hedonic scale rating from “extremely poor to excellent”. In general it is advisable to use 5 – 10 trained panelists and tell them the type of sample they are evaluating, but not much else. Random sample rating, coding and

37 presentation to the panelists is also very important to prevent bias. The number of samples should also be few (not more than 2-4 for citrus juices). Testing conditions, time of day, and procedure are all- important to the results. Finally the sample questionnaire and the type of taste test should be as simple as possible. Commonly tests of citrus juices are the triangle test, paired comparison, and product ranking. Glaszewiski et al.(1998) reported that juices from three strawberry cultivars were stored at 2 ºC and 25 ºC for six wk and evaluated for the sensory attributes fresh strawberry, strawberry-jam, off-flavor, and sweet. Fresh flavor declined while off-flavor increased during storage, with the largest changes occurring at 25 ºC. the off-flavor was described by panelists as an oxidized, acrid flavor very noticeable in product stored at 25 ºC after 2 wk of storage. Juice color and ascorbic acid also degraded much faster at 25 ºC. Browning results primarily from polymerization of anthocyanins and reactive phenolics and is major cause of color deterioration in strawberry preserves. 2.10 JUICE SHELF LIFE

Storage life was defined as the time to reach microbial counts of 1000000 CFU/ml (Howard and Dew 1995). Use of a factorial experimental design with interaction can help to identify the scores of sensory and chemical change during shelf life and ultimately this understanding can be related to consumer acceptance data and help predict shelf life from given ingredients, packaging and storage conditions. Beal (1998) identified many factors that can affect the shelf life of beverages (juices, milks etc). Some of the more important factors that affect shelf life are: raw materials, product formulation, processing, hygiene, packaging, storage/distribution, consumer

38 handling and display conditions. Preservation by chilling is normally limited to durations ranging from 2 days at 3 – 5 ºC to 7 days at 0 to 3 ºC. Most commercial reconstituted fruit juices are pasteurized and refrigerated at around 4°C for 30 days. Pasteurization increases the product preservatability (Ciobanu et al. 1976). In order to design a shelf life test that can be helpful to commercial and technical functions, it is important to have an understanding of all factors that affect the consumer acceptance, i.e. product formulation, processing and packaging as well as changes in sensory perception during storage that can be linked to consumer acceptance scores. Use of a factorial experimental design with interaction can help to identify the sources of sensory and chemical change during shelf life and ultimately this understanding can be related to consumer acceptance data and help predict shelf life from given ingredients, packaging and storage conditions. More than one type of test will often be used to answer the shelf-life test objectives.

2.11 Juice consumption in Sudan The Institute for Monetary and Economic Studies (IMES) consulting limited (UK) studied the Sudan market and prepared a report entitled "Overview of selected dairy products and Juice beverages in Sudan, 2002 ". A summary of the findings of this report is shown on table 2, from which it can be concluded that Sudan fruit juice market is quite promising and appealing for new products like Gudeim juice.

According to the aforementioned report up to 1995 the market for commercial, packaged juice products in Sudan has remained small (volume = 0.2 millions) due to use of squeeze fresh juice at home or purchase from juice stalls by cup and due to limited packaged juice

39 products locally-produced low quality concentrated drinks, sold in plastic containers or glass bottles.

From 1997 new companies started producing well-packaged juice drinks that lead to the increase in the consumption volume from 0.3 to 0.7 millions, the consumption increase continued at steady rate to the year 2000.The growth rate reached its peak (130 %) in 1997 and then dropped to 29 % in the next year growth became stable after that and expected to increase at steady rate in the following years. Per capita consumption showed significant increase in 1997 and then continued until reached 52.00 in the year 2000 and expected to increase through the following years at steady rate .

Lemon, Gunglaiz, Karkadey, Aradaib, Orange, Grapefruit , mixed fruit and mango juices are all sold either on the street sides, Cafterias or restaurants but we are not sure that they were included in the above mentioned per capita consumption estimated from the data provided by the IMES consulting limited (UK).

Table 2: Volume, growth rate and per capita consumption of ready to drink juice in Sudan Item Year *

40 1995 1996 1997 1998 1999 2000 2005 Volume (Million Liters) 0.2 0.30 0.70 0.90 1.00 1.3 2.3 Growth rate (%) N/A + 50 +130 + 29 + 11 + 12 Per Capita (ml) Consumption 8 12.00 32.00 36.00 40.00 52.00 91.60 * Calculated on the basis of 12% annual increase. ** Sudan Population approx. 25 millions Source: IMES Consulting Limited.(2002). Overview of selected Dairy Products and Juice Beverages In Sudan. A report prepared for Al-Rabie .

3. MATERIALS AND METHODS 3.1 Materials 3.1.1 Gudeim fruit

Dried Gudeim fruits were purchased from local market (Omdurman City market), kept in polyethylene bags and transported by air to Saudi Arabia, stored at room temperature until used. The origin of the Gudeim fruits in use is the southern part of Kordofan region in the western part of Sudan.

41 3.1.2 Water Potable water was used for the juice extraction, properties of which is shown in table 3. 3.1.3 Packages

Four types of packages most commonly used to pack soft drinks and fruit juices were used in this study. Normally glass bottle (GB), plastic bottle (PB) made from high density polyethylene (HDPE for blow molding)with closure made from linear low density polyethylene (LLDPE for injection molding), thermoforming plastic cups (PC) made from high impact polystyrene (HIPS330+PS100 or 125 for thermoforming) sealed with aluminum foil lid, and tetra top cartons. The packages were obtained from the local market in Al-Hofuf, Kingdom of Saudi Arabia. 3.2 Methods

Assessment includes juice yield calculation, physiochemical properties [proximate composition, titratable acidity, minerals content, pH, color evaluation, soluble solids (ºBrix), viscosity, specific gravity and stability],microbiological analysis (total count, coliform, Yeast and Mould), sensory evaluation and storage life.

3.2.1 Juice extraction

The fruits were manually sorted, weighed on an electronic balance (Type PB5001-S.Mettler Toledo, Switzerland). The protocol of preparing Gudeim fruits for juice production is depicted in Fig.2. Weighed amounts of Gudeim fruit namely 250, 350 and 500 g were soaked in potable water in the ratio of 1:4, 1:3 and 1:2 ( fruit : water).The water quantity used for extraction was measured using volumetric cylinder (Pyrex 3022 TC 20 ºC). Fruits were soaked ( Fig. 3 ) for 2 hrs either at room temperature for cold extraction or at 65 ºC for hot extraction, in this case a water bath (Memmert Gmbh+co

42 Germany, Type: WB 14 Nemtemp = 100 ºC) was used to keep the temperature of the water at 65ºC. The temperature was measured using a digital thermometer (Hanna instruments type H93510). Juice was extracted from the soaked fruit either manually i.e. hand pressing (H) or mechanically by blending ( B ) using Molinex -easy compact, Type ABMI 42E/800- 19109. Extracted juice was immediately filtered using a 710-µ-aperature laboratory test sieve (BS 410 /1986 made by Endicott's Ltd. London, England). The volume of obtained juice was measured for each treatment. Part of the juice was used for the initial measurements and evaluations. The rest of the juice was packed in Plastic Cups ( PC ) , Tetra Top ( TT ) carton , Glass Bottle ( GB ) and Plastic Bottle ( PB ) size 250 ml and stored refrigerated ( 3±1ºC ) until used at the appropriate time for further analysis or evaluations. Gudeim juice extraction process is summarized in fig.4. 3.2.2 Yield calculation

The yield of Gudeim juice was calculated according to the following equation:

juice wt X 100 Yield % = fruit + water wt

43 Unsorted

Sorted fruit

Culled fruits & foreign matters

Washed sorted fruit

Fig. 2: The protocol of preparing Gudeim fruits for juice production

Fig. 3: The soaking step in Gudeim juice production.

Fruit

Washing and cleaning

Cold soaking Hot soaking

Hand pressing extraction Blending extraction

Filtration

Packaging

Storage at about 3ºC for up to 28 days

Fig. 4: A flow diagram for Gudeim Juice extraction, packaging and storage.

3.2.3 Physicochemical assessment

46 3.2.3.1 Color measurement Color of Gudeim juice was measured objectively using Hunter lab color measurement device (Hunter color Quest 45/0, Hunter Associates Laboratory, Reston, VA. USA) to measure Hunter values L*, a* and b*. These values were then used to calculate the saturation index and Hue angle according to following equations: Saturation index: SI = ( a ² + b ²) ½ - (tan ¹b/a) x 180 Hue angle: H = π a = Hunter a* value b = Hunter b* value tan = tangent Color of the juice was evaluated initially (day 0) and every 2 days up to the 10th day of storage. 3.2.3.2 Viscosity measurement For measuring the viscosity a stop watch and a 100 ml viscosity cup type acc. DIN 53 211 (measuring viscosity range from 0.0055 to 32 pas) were used. Viscosity was expressed as flow time in seconds. The viscosity of cold and hot extracted juice was measured once immediately after extraction. 3.2.3.3 Soluble solids (ºBrix) Soluble solids were determined at 20°C using a Hand refractometer (Hand Refractometer, Tago Japan) with degree ºBrix scale 0-32. 3.2.3.4 pH measurement The pH was determined by immersing pH electrode in gudeim juice placed in a 50 ml beaker. Sufficient juice to cover the tips of the electrodes was used. A digital pH meter (Cole-Parmer instrument Co. Vernon Hills, Illinois, USA) was used for the measurement.

3.2.3.5 Total acidity Ten mls of Gudeim juice were taken in a 50ml beaker and

47 phenolphthalein was added as an indicator. This was titrated carefully with 0.1 N NaOH and titratable acidity was determined using the following formula:

Titer Value X 0.1 X 64 X 100 Total acidity (as citric acid %) =

Volume of sample X 1000

3.2.3.6 Stability The stability of semi clarified juice was measured by placing 100 ml of thoroughly mixed juice in a 100 ml. graduated cylinder and allowed to stand for 24 hrs. At the end of 24 hrs, it is evaluated according to the following Euro citrus (1990) scale after examination for visible physical separation of serum. Scale of separation: 0 – 10 ml. Separation : slight 10 – 20 ml. Separation : moderate. 30 – 40 ml. Separation : severe. Over 40 ml. Separation : extreme

3.2.4 Proximate composition

Moisture, protein, fat and ash content: of Gudeim fruit and juice were determined according to the AOAC(1995) procedure. The carbohydrate content was determined by difference. Fiber content was determined according to the AOAC procedure (AOAC, 1995). 3.2.5 Minerals The ash was further analyzed for individual mineral content using an inductively coupled plasma (ICP) emission spectrometer ( Plasma 400, Perkin Elmer) at an operating conditions specified by the manufacturer.

48 3.2.6 Sugars

Glucose and fructose were measured by according to the AOAC(1995) procedure using a high performance liquid chromatography ( HPLC) from Gilson (France).

3.2.7 Microbiological analysis 3.2.7.1 Total bacterial and fungi counts

Well homogenized samples were serially diluted with peptone water and plated on plate count agar (PCA) for total flora counts and on acidified (10% tartaric acid) potato dextrose agar for mould and yeast counts. Plates were incubated at 30°C for 48 hours for total flora and for 5 days for moulds and yeast. 3.2.7.2 Total coliform counts

Well homogenized samples were serially diluted with peptone water and plated in Petri plates in duplicate. The colony forming units (CFU) were determined using the red bile agar (VRB). Plates were incubated at 37 ºC for 48 hrs. Microbial counts were determined initially (day 0) and up to the 7th day of storage.

3.2.8 Sensory evaluation

Gudeim Juice samples were placed in plastic cups coded with 3-digit- numbers. Cups were capped and served to panelist at a temperature of 20 °C. Water was provided for mouth cleansing. An 8-member sensory panel, consisting of the staff members of food science and technology department, college of agricultural and food sciences, King Faisal University, K.S.A. and staff of juice processing

49 plant from the same area of king Faisal university, semi trained according to the procedure of Cross et al. (1978). The panelist were semi trained in five training sessions to familiarize them with gudeim juice and the parameters to be measured namely visual color, taste, aroma and overall acceptability of the juice. Aroma of gudeim juice was evaluated by sniffing headspace in the cup; taste was evaluated by mouth (tongue) to determine the degree of sweetness, sourness and bitterness if any. Finally the panelist decides the overall acceptability bearing in mind the taste, aroma and color of the juice tested. Color, taste, aroma and overall acceptability attributes were evaluated using a 7-point hedonic scale (7= extremely like, 4= neither like nor dislike , 1 = extremely dislike). The juices were evaluated initially (day 0) and at 4, 7, 10 and 14 days of refrigerated storage.

3.2.9 Storage life evaluation

Attempts will be made to make use of all the data collected on the physicochemical, sensory and microbiological properties of Gudeim juice stored refrigerated for up to 28 days, to estimate the storage life of the Gudeim juices under investigation. 3.2.10 Experimental Design and Statistical Analysis

A 2x2x4 factorial experiment with 3 replications was used to study the juice yield, characteristics and shelf life of Gudeim (Grewia tenax) juice. The data collected were subjected to analysis of variance and whenever appropriate the mean separation procedure of Duncan was employed ( Steel and Torrie, 1980 ). The SAS program (SAS, 2001) was used to perform the GLM analysis.

50 4. RESULTS AND DISCUSSION

4.1 Quality of water for juice extraction The properties of water used in the extraction of GJ, in the three replicates, compared with those suggested by a group of experts (JECE/FAO) are shown in table 3. While the pH of water used for the extraction of GJ, in the three replicates, is within the pH range suggested by the Codex Alimentarius group of experts, the rest of the properties are far way better i.e. less than the limits suggested by the group. Overall, the properties of water used to extract Gudeim juice in the three replicates in this study were either similar or mostly higher than the standards suggested by the Codex Alimentarius group of experts (JECE/FAO). 4.2 Fruit proportions

Before washing, the flesh of Gudeim fruit represents approx. 49% (table4). Upon washing, the proportion of the flesh of the Gudeim fruit increased to 59%. Flesh to seed ratio increased from 0.96:1 to 1.43:1 upon flash washing. On the average the flesh and seeds represents 54% and 46% of Gudeim fruit respectively with a flesh to seeds ratio of 1.17:1. Yadav (1998) reported that Grewia asiatica (phalsa) Indian type and Miami 12489 type had a flesh to seed ratio of 6.13:1 and 5:1 respectively. Apparently varietal difference can be assumed to account for the observed difference in the flesh to seed ratio of the two species (Grewia asiatica vs. Grewia tenax). Another factor that could have contributed to the observed difference in the flesh to seed ratio between the two species is climatic conditions to which they were subjected in addition to the cultural practices. Regardless of the factors that lead to the difference in the flesh to seed ratio and based on the higher flesh to seed ratio we can safely conclude that Grewia asiatica is better than Grewia tenax for juice production but this

51 should not be taken as an absolute judgment as we don't have a data to compare the organoleptic properties of the two species.

Table 3: Properties of water used in Gudeim juice extraction Parameter Control* Actual limit Rep-1 Rep-2 Rep-3 pH – Value 6.8-7.0 6.90 6.80 6.78 Total Dissolved Solids ( mg/l) <300 150 120 108 Residual Chlorine (ppm) Nil Nil Nil Nil Sulfate (mg/l) < 200 18.28 18.12 20.80 Ca (mg/l) < 75 7.20 7.05 8.15 Na ( mg/l) < 120 22.11 23.50 21.8 Fe (mg/l) < 0.1 0.02 0.03 0.02 Cu (mg/l) < 0.05 0.01 0.02 0.01 Total Bacterial Count (CFU/ml) < 10 1 Nil Nil Coliform Bacterial Count ( CFU/ml) < 1 Nil Nil Nil * Reference: Draft Code of Practice for the Quality of Water Used for the Reconstitution of Fruit Juices Concentrates, Joint ECE/FAO Codex Alimentarius group of experts on standardization of fruit juices, Geneve, July 1979.

Table 4: Gudeim fruit parts proportion before and after washing Item Before washing After washing Average Value % value % Value % Whole fruit wt. gm /100fruits 12.93 100 12.93 100 12.93 100 Flesh wt. (gm) 6.32 48.9 7.61 58.9 6.97 54 Seeds wt. (gm) 6.61 51.1 5.32 41.1 5.97 46 Flesh to seed ratio 0.96: 1 1.43: 1 1.17 : 1

53 4.3 Yield

Upon extraction the flesh part of the fruit went in the juice and a sizeable portion of it was discarded as a waste (Fig. 5), this is particularly so for hand pressed treatment. Examination of table 5 suggests that extraction ratio of 1:4 (Gudeim fruit: H2O) gave the highest juice yield among all extraction ratios tested in this study. Generally irrespective of the extraction temperature (cold or hot) or extraction method (Hand pressing or blending) Juice yield decreases (P < .05) as the extraction ratio increases i.e. the higher the extraction ratio the lower the Juice yield. Within extraction ratios, cold extraction method (Pool of CB and CH) gave significantly (P < .05) higher yield than hot extraction method (Pool of HB and HH) in The case of extraction ratio of 1:4, while for the extraction ratios of 1:3 and 1:2 the trend continued however the yield of cold extracted juice is only numerically higher (P>. 05) than those of hot extracted juice. Within extraction methods, at an extraction ratio of 1:4, cold extraction and blending (CB) gave the highest yield (77.11%) among the other methods. Also comparison of CB with hot extraction and blending (HB) revealed that CB had higher yield (P < .05) than HB. Again comparison CH and HH revealed that CH had higher (P < .05) yield than HH. The same trends were observed in the other extraction ratios (1:3 and 1:2) where the difference in yields between CB and HB, and between CH and HH were only numerical (P >. 05). Apparently cold extraction gave better yield than hot extraction. Beveridge et al. (1987) noted that treatment of apple mash with enzyme prior to juice extraction resulted in a higher juice yield than heat-treated apple mash. Cold extraction and hand pressing at an extraction ratio of 1:4 (Gudeim fruit: water) gave a juice yield of 76.62 % (calculated from table 5). A value which is slightly higher than that obtained by Westmeier and Kraus (1999) under similar condition (75 % yield ).

Fig. 5: Gudeim waste after the juice extraction by hand pressing, hull ( left) and seeds ( right).

Table 5: Effect of extraction method and extraction ratio on the yield of Gudeim juice Extraction Method Extraction Ratio 1:4 1:3 1:2 CB 77.11 Aa 59.27 Ab 54.21 Ac CH 76.62 Aa 59.60 Ab 54.52 Ac HB 74.63Ba 58.62Ab 53.32 Ac HH 75.58Ba 58.46Ab 53.57Ac * Means in the same row bearing different superscript small letters are significantly different ( P≤ 0.05 ). ** Means in the same column bearing different superscript capital letters are significantly different ( P≤ 0.05 ). N= 3

4.4 Proximate analysis The proximate analysis of Gudeim fruit and Gudeim juice is shown in table 6. Obviously the water content of Gudeim juice is way higher

56 than Gudeim fruit. This is because of the added water upon extraction of the juice from the flesh of Gudeim fruit. Like most other fruit juices, water constitute the major portion of Gudeim juice (table 6) and it is within the 85-95 % water content of most soft drinks (Taylor, 1998). Contents of ash, fat, protein and carbohydrate of Gudeim juice were only < 10%, 4.9%, 5.7% and 55.7% respectively (calculated from table) of that found in Gudeim fruit. Hence with the exception of carbohydrates the greater proportion of these components is lost in the left over of Gudeim fruit after extraction. Carbohydrate with 8.47 % is the second major component of Gudeim juice. Comparison of the proximate composition of Gudeim fruit with that reported by Yadav (1999) for phalsa fruit (Grewia asiatica) reveal that Gudeim fruit (Grewia tenax) had higher moisture, protein, ash and fructose content, but less carbohydrate. Ash, fat, crude protein and carbohydrate of Gudeim fruit reported in this study are similar to that reported by Abdelmuti (1991).

Compositions of representative fruits in comparison with Gudeim fruit are seen in table 7. Looking at this table we can say that generally the water contents for all fruits are greater than 73 % and frequently higher than 84 %. Gudeim fruit shows less water content compared to other fruits. In all these fruits neither the protein content is greater than 1.3 % or fat content greater than 0.5 %. The contents of carbohydrates in Gudeim are very close to apple contents and so do ash contents. Among these fruits the composition of apple is the closest one to the composition of Gudeim (table 7).

Table 6: Proximate composition of Grewia tenax juice and fruit Item Juice Fruit Water 90.60 73.49 Ash 0.41 4.4 Fat 0.02 0.41

Protein (N x 6.25) 0.37 6.5

Carbohydrates 8.47 15.2 Crude Fiber 0.13 ND ND= Not determined

Table 7: Typical chemical composition of some fruits (edible portion) compared to that of Gudeim. Fruit Carbohydrates Protein Fat Ash Water Banana * 24 1.3 0.4 0.80 73.5 Orange * 11.3 0.9 0.2 0.50 87.1 Apple * 15 0.3 0.4 0.30 84 Strawberries * 8.3 0.8 0.5 0.50 89.9 Melon * 6.0 0.68 0.2 0.40 92.8 Gudeim 15.2 6.5 0.41 4.40 73.49 * Source: Food Composition Tables, F.A.O United Nations, Rome, 1982

59 Fruits composition differs according to fruit group (berries, cherries, grapes, melons, drupes, pomes, and citrus fruits), variety, cultivation practice and climate. Most of fresh fruits are high in water, low in protein, and low in fat but a good source of carbohydrates and minerals (Stewart 1982). Expectedly Gudeim fruit has higher (P< 0.05) minerals than Gudeim juice from cold or hot extractions (table 8). The different minerals found in Gudeim fruit were extracted in the juice in variable percentages ranging from 0 to 21%. Mg (calculated from table 8) is the most extracted mineral, followed by Cu, K and Zn. The rest of the minerals are extracted in the juice at less than 10% of their content in Gudeim fruit. This may indicate that most of the mineral found in the whole fruit could be found in the seed or hull portion of the fruit rather than pulp which most goes in the juice, however for Mn the entire amount may be found in the seed or hull of the fruit. With the exception of Na hot extraction resulted in a substantial (P < 0.05) decrease in the mineral contents of Gudeim juice, possibly due to binding with other components that don't go in to the juice. Bockelmann and Bockelmann (1998) reported that hot extraction results in the decrease of total solids in the Soya bean drinks. 4.5 Sugar content Glucose and fructose are the two main sugars in Gudeim fruit and juice (table 9). Fructose represents 90% and 79% (calculated from data on table 9) of the sugars in the Gudeim flesh and Gudeim respectively, accordingly fructose is the predominant sugar. Babsky et al. (1986) noted fructose is the predominant sugar in subtropical fruits like apples and pears. On the other hand Buglione and Lozana (2002) noted that fructose to glucose ratio is approximately one. In the current study fructose to glucose ratios in Gudeim fruit and Gudeim juice were approximately 9 and 3.7(calculated from data on table 9) respectively.

Table 8 : Minerals contents of Gudeim fruit and juice and the effects of extraction temperature on the minerals content of Gudeim Juice ( ppm). Gudeim Juice Mineral Gudeim fruit Cold Extraction Hot Extraction P 347a 134b 121c Ca 6922a 594b 413c Mg 1314a 276b 185c K 9280a 1421b 1036c Na 2159a 254c 333b Cu 8.53a 1.47b 0.73c Fe 98.26a 6.73b 1.71c Mn 6.54a 0b 0b Zn 14.26a 1.45b 0.81c *Means in the same row bearing different superscript letters are significantly different ( P≤ 0.05 ). N= 3

Table 9: Sugar contents of Gudeim flesh and juice (%). Sugar Fruit flesh Fruit juice Glucose 2.30 0.6 Fructose 8.60 5.4 Maltose - - Sucrose - - Total 10.9 6.0 - = Traces.

A number of researchers believe that there is a practical interest in the comparative reactivity of fructose and glucose and their influence

62 on quality. Both of these sugars in the presence of glycine are involved in Millard browning reaction. It is generally accepted that fructose initially brown at a faster rate than glucose but is later overtaken by glucose. Using accelerated storage conditions similar findings were reported by Reyes et al. (1982). In this study, Glucose and fructose contents of Gudeim fruit were 8.7& 32.8%(calculated on dwtb ) respectively. The Glucose content was far less than those reported by Abdel muti (1991), however fructose content (on dry wt basis) of our study was higher (32.8 vs. 24.3%). while Abdulmuti (1991) reported a 1.6% Sucrose in Gudeim fruit, in the current study only traces of sucrose were found. Total sugar of Gudeim fruit was similar to that in phalsa (10.9% vs. 10.27%) reported by Morton (1987). To our knowledge, sugar content of Gudeim juice was not reported before; accordingly there were no data in the literature to compare.

4.6 Visual features of Gudeim juice

Although Gudeim fruit look like deep red with some unmissed yellow color, its fresh juice is characteristically bright yellowish in color which slightly darken upon storage (Figs. 6 and 7). The two pigments responsible for red and yellow color in fruit and fruit juices are anthocyanins and carotenoids; this may suggest that Gudeim is rich in these two pigments. Also the contribution of iron to the color appearance of Gudeim juice or Gudeim fruit should not be under scored. The data presented earlier in Table 8 suggest that both Gudeim fruit and Gudeim juice has substantial amounts of iron. Initially Gudeim juice from cold or hot extraction had an appealing color (Fig. 6) however it started to darken upon refrigerated storage ( Fig. 7 ). Gudeim Juice resembles Gamardeen juice in color

63 appearance and texture.

Fig. 6: Color appearance of Gudeim Juice from cold (upper picture) and hot extraction ( lower picture ) immediately after extraction.

Fig. 7: Gudeim Juice from cold ( right ) and hot ( left )extractions after 7 days of storage at about 3°C showing evidence of darkening.

4.7 Juice stability When the juices from the different treatment were allowed to stand for 24 hrs, they separated into two layers. Irrespective of the extraction temperature the depth of the liquid phase layer is less in the juice obtained by blending (Fig. 8 b) compared to that of the juices obtained by hand pressing( Fig.8 a). Also when extraction temperature was considered, the depth of the liquid phase layer of hot extracted juice is greater than that of cold extracted juice. Again within the same extraction temperature the depth of the liquid phase layer is bigger in the juice obtained by hand pressing (Fig. 9). To test further the stability of the juices obtained, the clear liquid phase was collected and allowed to stand for 24 hrs in graduated volumetric flask and the separation layer was measured. Apparently after clarification hot and cold blended juices are more stable than cold and hot hand pressed juices as they have less visual separation (Table 10).

4.8 Physicochemical Properties

The relative density of Gudeim juices irrespective of extraction method or extraction temperature is similar or quite comparable to that of orange, apple, grape, mango, and apricot juices and higher than that of tomato, lemon and guava juices (table 11). Within Gudeim juices, CB, CH, HH and HB had similar relative densities (Table 11). Likewise the total soluble content (ºBrix) of Gudeim juice is comparable to apricot, and guava, less than mango, apple, orange and grape juices but higher than that of tomato and lemon juices. Taylor (1998) reported that the AIJN code of practice lays down the

66 basic requirements for 18 fruit juices in terms of Brix and relative density. This list gives a prescribed number of physical and chemical parameters for a particular fruit, or fruit juice, it constitutes the bare minimum of testing but not to prove juice authenticity.

Fig. 8: Separation of Gudeim Juice from cold and hot hand pressed ( a ) and cold and hot blended ( b ) after allowed to stand for 24 hrs. Note the clear difference in the depth of

67 the liquid phase ( bars ).

Fig.9: Depth of separation layer of Gudeim Juice from hot hand pressed- HH- (left ) and hot blended ( right) after allowed to stand for 24 hrs. Note the clear difference in the depth of the liquid phase ( bars ).

Table 10: Stability tests result for a semi-clarified Gudeim juice. Juice sample Visual separations (ml) Rep-1 Repl-2 Rep-3 Mean CB 3 2 3 2.67 CH 15 14 14 14.33 HB 2 2 3 2.33 HH 10 11 10 10.33

Table 11: Natural fruit juice Brix & relative density in comparison with Gudeim juice Relative Density (20/20 Fruit juice ºC) ° Brix Gudeim CH* 1.056 9.00 Gudeim CB* 1.055 9.10 Gudeim HH* 1.061 9.25 Gudeim HB* 1.062 9.35 Orange** 1.040 10.00 Apple** 1.040 10.00 Grape** 1.055 13.50 Lemon** 1.028 7.00 Apricot** 1.041 10.20 Tomato** 1.015 4.00 Mango** 1.057 14.00 Guava** 1.034 8.50 * = Data from current study. ** = From Ref.: AIJN (Association of the industry of juices and nectars from fruits and vegetables of the EU) Code of practice 1st completion, February 1996

Physiochemical properties of cold extracted Gudeim juice and hot extracted juice is shown in table 12. Apparently the extraction temperature had no effect (p > .05) on the total soluble solids (ºBrix), pH, total solids and specific gravity of the two juices. However the treatment significantly (p < .05) affected both titratable acidity and viscosity, hot extracted juice had less titratable acidity and viscosity than cold extracted juice. Result presented in Table 13 show that extraction method (hand pressing and blending) significantly (p < .05) affected pH, titratable acidity and soluble solids (ºBrix) where hand pressed juice had higher total soluble solids and pH but less titratable acidity than those of the juice obtained by blending. Result presented in Table 14 show that extraction method and extraction temperature (CB, CH, HB, HH) significantly (p < .05) affected pH, titratable acidity and soluble solids (ºBrix). Among extraction methods HB gave a juice with the lowest (p <. 05) soluble solids (ºBrix) in the favor of CB method (Table 14). Again HB had the lowest pH and highest acidity among the extraction methods tested (p <. 05). Also HH had the highest pH and lowest acidity (p < .05) values among the extraction methods. Although the acidity of CB and CH methods differ significantly yet this difference was not reflected on the pH of the two methods as they have similar pH ( P ≥.05 ). The effect of storage period on the total soluble solids (ºBrix) was noticeable only after 14 days of storage on wards (Table 15). In the first seven days of storage the ºBrix value of the juice at 7 days of storage was similar (P>.05) to that at day 0 (initial value).

71 Results presented in Table 14 show that pH and titratable acidity significantly (P<. 05) changed during storage. While the pH showed a continuous decrease, titratable acidity showed a continuous increase with storage period. A significant (P<. 05) –ve correlation (r = -0.47) between pH and titratable acidity was noted (data not shown). The slight increase in the acidity of Gudeim juice might be partly due to the production of organic acids in the juice with increase in storage time.

Table 12 : Effect of extraction temperature on certain physicochemical properties of Gudeim juice. Property Cold Extraction Hot extraction ºBrix 9.33a 9.4a Titratable Acidity 0.31a 0.29b pH (unit) 4.08a 4.15a Total solids 10.1a 10.2a Viscosity (sec.) 12.01a 10.79b Specific Gravity 1.05a 1.06a Means in the same row bearing different superscript letters are significantly Different (P≤ 0.05). N= 3

Table 13 : Effect of extraction method on certain physicochemical properties of Gudeim juice. Property H B ºBrix 9.5a 8.95b Titratable Acidity 0.28b 0.33a pH (unit) 4.10a 3.93b Means in the same row bearing different superscript letters are significantly different (P≤ 0.05). N= 3 H= Hand pressed. B= Blending.

Table 14 : Effect of extraction method and extraction temperature on certain physicochemical properties of Gudeim juice Extraction method ºBrix pH Acidity % HH 9.83a 4.21 a 0.25 d CB 9.28 b 4.02 b 0.29 c CH 9.18 c 4.01 b 0.30 b HB 8.62 d 3.87 c 0.37 a * Means in the same column bearing different superscript letters are significantly different ( P≤ 0.05 ). N= 16

Table 15: Effect of storage period on certain physicochemical properties of Gudeim juice Storage period ºBrix pH Acidity % (days) 0 9.28 a 4.14 a 0.28d 7 9.28 a 4.09 b 0.30c 14 9.21 b 3.99 c 0.31b 21 9.14 c 3.89 d 0.34a * Means in the same column bearing different superscript letters are significantly different ( P≤ 0.05 ). N=16

Results presented in table 16 show that package types (PB, GB, PC, and TT) had no effects on the total soluble solids (οBrix) of Gudeim juice (p > .05). This indicates that none of the packages tested absorbed substantial amount of the soluble solids in Gudeim juice. Several investigators have reported on observation of certain component of fruit juices (particularly flavor compounds) and model solutions in contact with packaging materials (Halek and Meyers, 1989; Sadler and Braddock, 1991). With regard to pH and acidity % of Gudeim juice a slight effect of packages can be noticed. While PB and GB had similar (p>.05) pH and acidity, PC and TT package types had also similar (p > .5) pH and acidity. It is also noticed that the latter two packages had slightly lower (p < .05) pH value compared to that of PB and

GB package types. Likewise PC and TT had slightly higher acidity % (p< .05) compared to that of PB and GB. Initially (day 0) the amounts of soluble solids were affected by the extraction method with HH giving the highest value and HB giving the lowest value (table 17), the trend continued for the rest of the storage period. Within each extraction method, storage period had no effects on soluble solids (ºBrix). Initially (day 0) CB and HH had the Highest and lowest pH and acidity respectively among extraction methods. On the 7th day of storage CB and CH methods had similar pH and acidity ( P>0.05 ). The pH of these two methods were significantly higher than that

76 of HB ( P<0.05 ) but significantly lower than that of HH method. The acidity of CB and CH at this time (day 7) were similar ( P >0.05 ) but significantly ( P<0.05 ) lower and higher than that of HB and HH respectively. On day 14 and 21 of storage, CB and CH had similar (P>0.05) pH and acidity. On the 21st day of storage, the two methods had a similar pH (P<0.05) to HB method but significantly lower than that of HH (P<0.05).

Table 16 : Effect of package type on certain physicochemical properties of Gudeim juice Package type ºBrix pH Acidity % PB 9.25 a 4.05 a 0.30 a GB 9.23 a 4.05 a 0.30 a PC 9.22 a 4.01 b 0.31 b TT 9.21 a 4.00 b 0.31 b * Means in the same column bearing different superscript letters are significantly different ( P≤ 0.05 ). N=16

Table17 : Interactive Effects of extraction method and storage period on the total soluble solids ( Brix ) , pH and acidity of Gudeim Juice. Storage period Method ( days) Brix pH Acidity CB 0 9.30Ba ± 0.13 4.23 Aa ± 0.04 0.24 Cc ± 0.01 CB 7 9.30 Ba ± 0.13 4.11 Bb ± 0.12 0.29 Bb ± 0.01 CB 14 9.25 Ba ± 0.06 3.98 Bc ± 0.10 0.29 Bb ± 0.01 CB 21 9.25 Ba ± 0.06 3.75 Bd ± 0.10 0.35 ± 0.01 CH 0 9.20 Ba ± 0.07 4.11 Ba ± 0.02 0.28 Bc ± 0.01 CH 7 9.20 Ba ± 0.07 4.10 Ba ± 0.02 0.29 Bb ± 0.01 CH 14 9.18 Ba ± 0.05 3.97 Bb ± 0.01 0.29 Bb ± 0.01 CH 21 9.15 Ba ± 0.06 3.86 Bc ± 0.10 0.34 Ba ± 0.01 HB 0 8.70 Ca ± 0.05 3.92 Ca ± 0.08 0.33 Ad ± 0.01 HB 7 8.70 Ca ± 0.05 3.90 Ca ± 0.03 0.36 Ac ± 0.02 HB 14 8.58 Ca ± 0.15 3.85 Ca ± 0.01 0.39 Ab ± 0.01 HB 21 8.50 Ca ± 0.14 3.82 Ca ± 0.02 0.40 Aa ± 0.01 HH 0 9.90 Aa ± 0.13 4.28 Aa ± 0.04 0.25 Ca ± 0.01 HH 7 9.90 Aa ± 0.08 4.26 Aa ± 0.04 0.25 Ca ± 0.01

78 HH 14 9.85 Aa ± 0.10 4.18 Aa ± 0.05 0.25 Ca ± 0.01 HH 21 9.68 Aa ± 0.10 4.12 Aa ± 0.03 0.25 Ca ± 0.01 *Means in the same column for the same extraction method bearing different superscript small letters are significantly different ( P≤ 0.05 ). ***Means in the same column for the same storage period bearing different superscript capital letters are significantly different ( P≤ 0.05 ).

Within each extraction method, particularly CB and CH, while pH decreased with increase in storage period ( P<0.o5 ), acidity increased with increase in storage period ( P<0.05 ). The storage period did not affect (P>0.05) the pH of HB or HH juices. Again the storage period had no effect (P>0.05) on the acidity of HH juice. Although there was a continued significant increase in the acidity of HB juice, but this was not reflected on the pH of the juice samples from HB method. A summary of the physiochemical properties and yield of Gudeim juice in comparison to the most popular fruit juice in Sudan are shown in table 18. Apparently the physiochemical properties of Gudeim juice are quite comparable to these fruit juices common in Sudan.

4.9 Color evaluation

Cold extracted Gudeim juice has significantly (P<0.05) lighter color than Hot extracted Gudeim juice (Table 19). However when we look at the magnitude of this change we find that it is small (- 4.5%). On the other hand other Hunter values (a* and b*), SI and Hue angle of both cold and hot extracted juices are similar (P>0.05). So generally, extraction temperature had no effects on the color characteristics of

79 extracted juice. Goodman et al. (2002) observed no overall significant difference between the color of cold extracted and hot extracted tomato juice. Such finding was not supported by Bontovits (1981) who observed a color deterioration that correspond to two and a half color grades between cold and hot extracted tomato products. Grape juice extracted at 99 ºC was rated higher in color and flavor than the juice extracted at 60 ºC (Morris et al. 1986). It should be noted here that effects of extraction temperature depend on the temperature, extraction time, and nature of the fruit variety.

Table 18: A comparison between the physicochemical properties and yield of Gudeim juice and that of some tropical fruits juices Fruit Component ◦Brix Acidity % pH Yield % Brix/ acid ratio Guava* 3.0-11 0.36-0.66 3.2 25-30 20 Mango* 10-15 0.20-0.70 - 31 40 Papaya* 9-10 0.05-0.1 5-5.5 70 > 10 CEGJ** 9.33 0.31 4.08 76.8 30

HECJ** 9.40 0.29 4.15 75.1 32

80 * Source: Saint-Hilaire and Struebi (1982). ** Current study.

Table 19 : Effects of extraction method on the Hunter color values of Gudeim Juice. Hunter Values Extraction Method % Difference Cold Hot L* 52.17a 49.81b -4.5

a* 21.01a 21.16a +0.71

b* 48.67a 48.34a -0.68

SI 53.02a 52.75a -0.51

Hue 66.65a 66.37a -0.42

* Means in the same row bearing different superscript small letters are significantly different (P≤ 0.05).

The effects of storage period on the Hunter color values of Gudeim juice irrespective of the extraction methods is shown in table 20. All Hunter values showed a significant change (P< 0.05) with storage period, such a change varied from one Hunter value to the other. Generally by the end of storage period (10 days), the total change for each value varied from 2.4 – 10.53 % of its initial value. The greatest change was 10.53% and 9.55% for b* and SI values respectively. The minimal change was 2.4% for the Hue angle. As it is well known Hue angle describes what the average person envisions when speaking of color e.g. green, red, yellow and so on. Since the change in Hunter L*, a* and Hue angle was minimal, the overall change in the color of Gudeim juice during storage up to 10 days was also minimal probably due to the short storage period. BunLione and Lozana (2002) found that only one variety of the three Grape juice varieties studied showed a remarkable change in Hue angle parameter after prolonged storage. The stability of refrigerated sulfited and non-sulfited unpasteruized Muscadin grape juice during prolonged storage (9 wk) was attributed to absence or low levels of polyphenol oxidase ( PPO ) activity ( Sims et al. 1991 ; Sims et al. 1995).

82 It is well known that the naturally occurring colors of many food items undergo undesirable changes during storage. Fruit juice is no exception. Fruit and fruit products pigment usually deteriorate with storage time leading to visual changes in the color appearance. Changes in Hunter color values of CEGJ and HEGJ with storage period are shown in table 21. Changes in the Hunter color values L*, a* and b* were followed for up to 10 days of storage. Generally, throughout the storage period tested CEGJ had higher (P < .05) L* value than HEGJ (table 21). Also within each storage period CEGJ had lighter color than HEGJ. Hunter L* value of CEGJ showed much stability than that of HEGJ. Over the first 8 days of storage L* values of CEGJ were similar (P> .05), only on the 10th day of storage a significant reduction (P< .05) was observed.

Table 20 : Effects of storage period on the hunter color values of Gudeim Juice. Time Hunter Values (days) L* a* b* SI Hue 0 51.90a 21.45a 51.21a 55.51a 67.28a

2 51.28b 21.36a 48.80b 53.27b 66.34c

4 50.84c 21.35a 48.88b 53.35b 66.41c

6 50.68c 20.80b 45.82d 50.32d 65.56d

8 50.13d 20.84b 48.43b 52.65c 66.89b

10 50.11d 20.73b 47.92c 50.21d 66.60c

83 3.45% 3.3% 10.53% 9.55% 2.4%

*Means in the same column bearing different superscript small letters are significantly different ( P≤ 0.05 ). LSD= 0.29

Table 21: Interactive effects of storage period and extraction temperature on the Hunter color values of Gudeim Juice. Time Method Hunter Values (days) L* a* b* C 52.92Aa 21.43 Aa 51.24 Aa 0 ±0.09 ±0.17 ±0.03 H 50.89Ba 21.47 Aa 51.19 Aa ±1.86 ±0.25 ±0.27 C 52.74 Aa 21.50 Aa 49.69 Ab 2 ±0.06 ±0.22 ±0.25 H 49.81 Bb 21.22 Aa 47.92 Bb ±0.40 ±0.28 ±0.34 C 52.36 Aa 21.28 Aa 49.01 Ab 4 ±0.08 ±0.14 ±0.10 H 49.32 Bb 21.40 Aa 48.75 Bc ±0.50 2±0.35 ±0.33

84 C 52.63 Aa 20.84 Ab 46.75 Ac 6 ±0.27 ±0.10 ±0.28 H 50.72 Ba 20.76 Ab 44.89Bd ±0.32 ±0.09 ±1.27 C 51.49 Aa 20.58 Ab 48.31 Ad 8 ±0.12 ±0.14 ±0.08 H 48.77 Bc 21.09 Aab 48.54 Ae ±0.36 ±0.41 ±0.57 C 50.87 Ab 20.45 Ab 47.07 Ac 10 ±0.26 ±0.25 ±0.38 H 49.35 Bb 21.02 Aab 48.77 Ae ±0.13 ±0.25 ±0.37 *Means in the same column for the same extraction method bearing different superscript small letters are significantly different ( P≤ 0.05 ). ** Means in the same column for the same storage period bearing different superscript capital letters are significantly different ( P≤ 0.05 ).

Initially (day 0) Hunter a* and b* values of the CEGJ and HEGJ were similar (P >.05). Interestingly, within each storage period and throughout the storage period tested CEGJ and HEGJ had similar Hunter a* values. Within each extraction temperature Hunter a* values did not show any change with storage time till the 6th day of storage when their values were significantly lower (P< .05) than their values in the first 4 days of storage (table 21 ). For the first 6 days of the period tested CEGJ had numerically or significantly (P < .05) higher Hunter b* values than HEGJ. From the 8th day of storage onwards the two treatments had similar Hunter b* values (P > .05). Within each extraction temperature Hunter b* values decreased (compared to its initial value at day 0) with the increase in storage period. Both CEGJ and HEGJ reached their lowest values on the 6th day of storage. From there onwards they started to increase but never reached their initial value on day 0.

85 In conjunction with Hunter color L*, a* and b* values, Saturation Index and Hue angle can improve our understanding to the changes in the color of the CEGJ and HEGJ throughout the storage period. The saturation index is the attribute of color perception that expresses the degree of departure from the gray of the same lightness. While Hue angle is the attribute of color perception by means of which an object is judged to be red, yellow, green, blue or purple.

Changes in the saturation Index (SI) and Hue angles (Hue) of the CEGJ and HEGJ stored refrigerated for up to 10 days are shown in table 22. Initially (day 0), day 4 and day 8, SI of the CEGJ and HEGJ were similar (P > 0.05) , while on day 2 , 6 and 10 SI of the CEGJ and HEGJ were different (P < 0.05). On day 2 and 6 CEGJ had higher SI values than HEGJ.

Table 22 : Interactive effects of storage period and method of extraction on the Saturation Index and Hue angle of Gudeim Juice. Time (days) Method SI Hue 0 C 55.53 Aa ± 0.08 67.32 Aa ± 0.16 H 55.50 Aa ± 0.16 67.20 Aa ± 0.35 2 C 54.14 Ab ± 0.30 66.61 Ab ± 0.14 H 52.41 Bc ± 0.24 66.01 Ab ±0.30 4 C 53.45 Ac ± 0.07 66.55 Ab ± 0.14

86 H 53.25 Ab ± 0.31 66.28 Ab ± 0.39 6 C 51.18 Ae ± 0.30 65.98 Ab ± 0.06 H 49.46Bd ± 1.14 65.15 Ac ± 0.70 8 C 52.51 Ad ± 0.08 66.93 Aa ± 0.15 H 52.80 Ac ±0.46 66.85 Aa ± 0.42 10 C 51.32 Be ± 0.45 66.52 Ab ± 0.10 H 53.10 Ab ±0.33 66.69 Aa ± 0.33 * Means in the same column for the same extraction method bearing different superscript small letters are significantly different ( P≤ 0.05 ). ** Means in the same column for the same storage period bearing different superscript capital letters are significantly different ( P≤ 0.05 ).

The two treatments reached their lowest values on day 6 of the storage. Within each extraction temperature SI decreased (P < 0.05) with the increase in storage time (table 22). Within each storage period Hue angles of CEGJ and HEGJ were similar (P > 0.05) i.e. showed the slightest change with storage period. Changes in color and development of undesirable haze and turbidity during storage are common side-reactions in fruit juices that compromise commercial acceptability of bright red ultra-filtrated apple juice (Gokmen et al. 1998). Also several investigators (Constenla and Lozano 1995; Maier et al. 1994; Stutz 1993) concluded that polyphenolic compounds with relatively low molecular weights have been found responsible for physicochemical deterioration of apple juices and concentrates during storage.

87 The major visual color of mango, gamardeen and Gudeim juice is a mix of yellow and red. Accordingly gamardeen and mango juices were chosen to compare the color of GJ because their visual color resembles it to a great extent. Mango juice had the highest Hunter L* value followed by CEGJ, HEGJ and Gamardeen (table 23). GJ, irrespective of the extraction temperature, had more redness (a*) than mango and gamardeen juices (P<. 05). Mango juice has more yellowness (b*) than both Gudeim juices and gamardeen. The latter is less yellow (P<. 05) than mango juice but more than Gudeim juices (P<. 05). Also mango juice and gamardeen were superior in SI and hue angle to Gudeim juices. Species differences should be considered upon comparing Hunter color values of GJ with Mango and gamardeen. 4.10 Microbiological analysis Table 24 shows the effect of extraction temperature and storage period on total plate count (TPC), Coliforms and fungi (yeast and moulds) counts. Although Gudeim seeds were screened as indicated in the material and methods section and washed before the juice extraction process, yet appreciable numbers of microorganisms exist.

Table 23: Comparison of Gudeim juice Hunter color values with that

88 of Mango and Gamardeen juices. Gudeim Juice Hunter value Mango juice Gamardeen Cold Extraction Hot Extraction L* 62.20a 46.40d 52.17b 49.81c a* 20.74b 19.62c 21.01a 21.16a b* 78.67a 61.30b 48.68c 48.34c SI 81.36a 64.36b 53.02c 52.75c Hue 75.25a 72.27b 66.65c 66.37c Means in the same row bearing different superscript small letters are significantly different (P≤ 0.05). N= 3

Table 24: Effect of extraction temperature and storage period on certain microbiological properties of Gudeim juice (log10 CFU/ml ). Property Extraction Storage period (days) Temperature 0 2 4 7 % TPC Cold 4.00 Ac 4.48 Aa 4.38 Ab 4.40 Ab 10 Hot 3.65 Bc 3.85 Ba 3.78 Bb 3.76 Bb 3 Coliform Cold 2.00 Ac 3.11 Aa 2.64 Ab 2.56 Ab 2.8 Hot 1.70 Bc 2.97 Ba 2.23 Bb 2.15 Bb 2.6 Yeast & Cold 2.95 Ba 2.68 Bb 2.98 Aa 3.00 Aa 1.7 Moulds Hot 3.20 Aa 3.10 Aa 2.93 Ab 2.96 Ab 7.5 * Means in the same row bearing different superscript small letters are significantly different (P≤ 0.05). ** Means in the same column for the same microbiological property bearing different Superscript capital letters are significantly different (P≤ 0.05). N= 3

Several methods for reducing microorganisms numbers and toxins in fruit and vegetable juices have been studied by numerous investigators. Such methods include culling, washing; removal of decayed or damaged fruit or trimming of moldy portion of fruits and vegetables prior to processing can reduce microorganisms numbers or toxins in fruit and vegetable juices (Lovett et al. 1975; Sydenham et al. 1997; Jackson et al. 2003). Washing apples with high-pressure water spray prior to processing to apple juice was effective in

90 reducing patulin levels by 54% (Acar et al. 1998). A similar finding was reported by Jackson et al. (2003). Initially (day 0), irrespective of extraction temperature, Gudeim juice microbial counts were 3.82,

1.85 and 3.07 log 10 CFU/ml for total plate count (TPC), coliform and yeast and moulds (data not shown, however calculated from data in table 24 ). Initially (day 0) cold extracted Gudeim juice had significantly (p < 0.05) greater total plate count (4.0 vs. 3.65 log10

CFU/ml) and total coliforn count (2.0 vs. 1.7 log10 CFU/ml0 than hot extracted Gudeim juice (table 24). On the other hand hot extracted Gudeim juice had significantly (p<0.05) greater yeast and moulds counts (3.20 vs. 2.95 log10 CFU/ml) than cold extraction Gudeim juice. Generally TPC and coliforn counts of both cold extraction Gudeim juice and hot extraction Gudeim juice increased (p<0.05) with storage period (table 24). Interestingly, the counts in both CEGJ and HEGJ reached their peak after 2 days of storage. On the 4th day of storage the counts of TPC and coliforms of CEGJ and HCGJ decrease (p<0.05), from that at day 2 of storage. From day 4 to the end of storage period tested the counts of TPC and coliforn of both cold extraction contents of TPC and coliforn of both cold extraction and hot extraction Gudeim juice did not change (p>0.50). Some types of coliforn particularly E.coli 0157: H7 received good attention from researchers concerned with wholesomeness and safety of fruit and vegetable juices (Fisher and Golden 1998; Yuste et al. 2002; Nogueira et al. 2003). Other types of bacteria that are known to grow in vegetable and fruit juices include salmonella, listeria monosytogerms, and Bacillus cereus (Nogueira et al. 2003; Collado et al. 2003). Unexpectedly, initially (day 0) HEGJ contained higher yeast and mould counts (P<0.05) than CEGJ (Table 24 ). Yeast and moulds counts of CEGJ slightly increased (P>0.05) from 2.95 log CFU/ml at

91 day 0 to 3.0 log10 CFU / ml at the end of the storage period ( day 7 ) tested ( Table 24 ). On the other hand yeast and moulds counts of

HEGJ decreased (P < .05) from 3.2 log10 CFU/ml at day 0 to 2.96 log10 CFU/ml. The overall change in TPC and yeast and moulds counts at the end of storage period was minimal, while a considerable overall change in coliforms count (26-28%) at the end of storage period was noted.

4.11 Sensory evaluation

The effects of extraction temperature and storage periods on the sensory properties of Gudeim juice are shown in table 25. The visual color scores of CEGJ and HEGJ within each storage period were compared. Consistently and throughout the storage period tested CEGJ had significantly (p < .05) higher scores than that of HEGJ, indicating that panelists prefer the color of CEGJ. Such a subjective evaluation is consistent with objective evaluation using Hunter L* values presented in table 18. Within each extraction temperature, the visual color of Gudeim juice is affected by the storage period. The visual color of CEGJ was stable till the 7th day of storage (p < .05) to reach its lowest value i.e. tended to darken on the 14th of day of storage. Also visual color of HEGJ was stable till the 7th day of storage (p < .05). after that from the 10th day

Table 25 : Effect of extraction temperature and storage period on sensory properties of Gudeim juice. Extraction Propert Storage period (days) Temperature y 0 4 7 10 14 Co 5.23Aa 5.31 Aa 5.18 Aa 5.02 Ab 4.81 Ac Cold Ar 3.68 Ba 3.63 Ba 3.61 Ba 3.52 Ba 3.55 Ba Ta 4.76 Ab 5.00 Aa 5.04 Aa 5.11 Aa 4.83 Ab OA 4.19 Aa 4.25 Aa 4.17 Aa 4.02 Ab 4.05 Ab Co 4.88 Ba 4.92 Ba 4.86 Ba 4.71 Bb 4.29 Bc Hot Ar 3.94 Aa 4.03 Aa 4.17 Aa 4.14 Aa 4.06 Aa Ta 4.65 Aa 4.51 Ba 4.67 Aa 4.53 Ba 4.48 Ba OA 4.12 Aa 4.16 Aa 4.06 Aa 4.01 Aa 4.03 Aa *Means in the same row bearing different superscript small letters are significantly different ( P≤ 0.05 ). ** Means in the same column for the same sensory property bearing different superscript capital letters are significantly different (P≤ 0.05). N= 24. *** Co= color, Ar= Aroma, Ta= Taste, OA= Over All acceptability.

on ward its scores decreased significantly (p < .05) i.e. tended to darken more to reach its lowest value on the 14th day of storage. The

93 aroma (Ar) and overall acceptability (OA) of CEGJ and HEGJ were not affected (p < .05) by the storage period. Within all storage period tested, the panelists rated the Ar of HEGJ higher than that of CEGJ (p < .05). Probably some of the objectionable volatile compounds might have been expelled during hot extraction. Initially (day 0), the panelist found the taste of CEGJ & HEGJ to be similar ( p > .05), however from there till the end of storage period tested, they significantly preferred the taste of CEGJ to that of HEGJ. While the taste of HEGJ was not affected by storage period ( p ≥.05), the taste of CEGJ showed a fluctuation as the scores were low initially (day 0), increased gradually from the 4th till the 10th day of storage and to decrease at the end of storage period to a score almost similar to that of day 0. The Aroma and taste results of the panel are casted by the fact that none of the panelists who contributed in this study had a previous experience with Gudeim juice except the semi training that they were subjected to prior to the evaluation sessions.

4.12 Shelf life

The total soluble solids (◦Brix) of CEGJ did not change with the storage time (P > .05) however it showed a slight decrease at the end of storage period (28 days). Also HEGJ showed no change in ◦Brix over 21 days of storage but significantly declined at the end of storage period (28 days). The two juices (CEGJ and HEGJ) had similar (P>.05) ◦Brix values on the 28th day of storage. The titratable acidity of CEGJ increased significantly (P<.05) with storage period (table 26). Similarly titratable acidity of HEGJ increased significantly (p<.05) with the storage period (table 26). Within each storage period, HEGJ had continually higher titratable acidity (P<.05) than CEGJ (table 26). In the first 7 days of storage

94 neither the pH of CEGJ nor that of HEGJ changed (P>.05), from the 14th day onward the pH of both juices

Table 26: Effect of extraction temperature and storage period on certain physicochemical properties and sensorial acceptability of Gudeim juice. Property Temperature Storage period (days) of Extraction 0 7 14 21 28 Brix Cold 9.20Ba 9.20 Ba 9.15 Ba 9.15 Ba 9.10 Aa Hot 9.3 Aa 9.3 Aa 9.3 Aa 9.3 Aa 9.10 Ab Titratable Cold 0.28 Bd 0.29 Bc 0.29 Bc 0.33 Bb 0.34 Ba acidity Hot 0.29 Ae 0.30 Ad 0.33 Ac 0.40 Ab 0.41 Aa PH Cold 4.11 Aa 4.10 Aa 3.96 Ab 3.92 Ab 3.85 Ac Hot 4.10 Aa 4.15 Aa 3.95 Ab 3.93 Ab 3.87 Ac Acceptabili Cold Y Y Y Y No -ty Hot Y Y Y Y No *Means in the same row bearing different superscript letters are significantly different ( P≤ 0.05 ). N= 3 ** Means in the same column for the same physicochemical property bearing different superscript capital letters are significantly different (P≤ 0.05).

(CEGJ and HEGJ) showed a significant (P<.05) or a numerical (P>.05) decrease. Cold or hot extracted Gudeim juice was sensorially acceptable till the 14th day of storage (table 26). These observations coincide with the upper observations on pH and acidity of the two juices. It looks like a juice is acceptable when its pH is around or higher than 4.0 and its titratable acidity is below 0.34 %. However a clear demarcation between the acceptability and unacceptability using the physiochemical properties particularly pH and acidity from the current study can not be suggested. Hence further investigation is needed before a concrete conclusion is suggested. In conjunction with the upper findings, further observations on these juices were made by the panelists are summarized in table 27. Regardless of the extraction method or package type all the juice samples had fermented taste, fermented odor, had showed a separation into two layers and all were deemed unacceptable after 21 days of storage. The appearance of Plastic bottles (PB) filled with cold or hot extracted juices immediately after extraction was normal (Fig. 10) i.e. no evidence of blowing. Only one sample from CEGJ packed in plastic bottle (PB) showed evidence of blowing (Fig.11), the rest of CEGJ packed in the other containers (particularly TT and PC) did not show any signs of blowing. Also none of HEGJ package showed any sign of blowing. With the exception of CEGJ sample packed in TT, which had a bright yellowish-red color after 21 days of storage, the color of most HEGJ and CEGJ samples was dull yellowish-red.

Table 27: Summary of observations on refrigerated Gudeim juice after21days of storage in four types of Packages

Observations Extraction Package Overall temperature type Blowing Separation Color Odor Taste Acceptability G B NA Y BY R Fermented Fermented Unacceptable TT N Y BY R Fermented Fermented Unacceptable C PB Y Y DY R Fermented Fermented Unacceptable

PC N Y DY R Fermented Fermented Unacceptable DY R GB NA Y Fermented Fermented Unacceptable DY R H TT N Y Fermented Fermented Unacceptable DY R PC N Y Fermented Fermented Unacceptable

DY R PB N Y Fermented Fermented Unacceptable C = Cold extraction . H = Hot Extraction. NA= not applicable. BYR= Bright Yellowish Red. DYR = Dull Yellowish Red

Fig. 10: Bottled Gudeim juice immediately after cold ( blue cap ) or hot ( red ) extraction.

Fig. 11: Evidence of blowing (arrow) in cold extracted Gudeim juice after 28 days of refrigerated storage.

5. CONCLUSIONS AND RECOMMENDATIONS 5.1 CONCLUSIONS

1. The yield of Gudeim juice obtained from the ratio of 1:4 (fruit to water) was 76 % , this ratio was found to be the most appropriate for juice extraction. 2. The hand pressing method is more appropriate than the blending method for the juice extraction. 3. Generally Gudeim juice physicochemical properties are similar to most of the popular fruit juices in Sudan. Freshly extracted Gudeim juice was found to be acidic (pH 4.0), had a total acidity in the range of 0.25 to 0.29 % with a total soluble solids of 9.36 ºBrix with a sweety taste and attractive yellowish red color. 4. Gudeim juice is rich in minerals particularly potassium and iron. 5. The microbiology of the unpasteurized Gudeim juice was found to be reasonably safe. 6. The physicochemical properties of Gudeim juice were stable for a period of up to 14 days when stored refrigerated in glass bottles, plastics bottles ,plastic cups and tetra top cartons type of packages. 5.2 RECOMMENDATIONS

1. Commercialization of Gudeim juice as one of the national fruit juices and drinks. If the production of Gudeim juice is to be commercialized further work is needed to duplicate the hand pressing extraction technique mechanically, and to study the juice ability to be pasteurized. 2. Genetic improvement of Gudeim fruit to improve its processing potentialities. 3. Further investigations are needed to acertain the wholesomeness and safety of unpasteurized Gudeim juice. 4. To study thoroughly the effect of clarification technique on the nutritive value of Gudeim juice. 5. More investigations are needed on the packaging of Gudeim juice. 6. Further investigations are needed to explore the potentialities of Gudeim products for use in other food product.

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