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العنوان
Biochemical, Microbiological and Technological Studies on Fruits of Some Date Cultivars in South Valley/
المؤلف
Abdel-Karim, Naglaa Abdel-Sabour Ahmed Ahmed.
هيئة الاعداد
باحث / نجلاء عبد الصبور أحمد أحمد
مشرف / وفيق سند موسى
مشرف / محمد عبد الحميد حسن
مناقش / أحمد عبد العزيز الرفاعى
مناقش / بلبل رمضان رمضان
الموضوع
Food - Analysis.
تاريخ النشر
2012.
عدد الصفحات
82 p. :
اللغة
الإنجليزية
الدرجة
ماجستير
التخصص
علوم وتكنولوجيا الأغذية
الناشر
تاريخ الإجازة
26/6/2012
مكان الإجازة
جامعة أسيوط - كلية الزراعة - Food Science and Technology
الفهرس
Only 14 pages are availabe for public view

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Abstract

The date palm ( Phoenix. dactylifera L.) is one of the eldest of cultivated tree fruits, with its origin in prehistoric times and records indicating culture as early 3000 B.C. in the Near East and North Africa. Dates are an important crop in the desert regions of the world; the date palm tree is among the most presented plants in our Holy Book, the Quran as well as Sunnah.
Egypt lies in the first largest date producer among Arab countries where it produce about 1.130.000 tones. Although there are many known varieties of dates in Egypt, there is also many of unknown dates (seedling) with low or no marketing prices.
In this investigation, a comparative study of physical properties and chemical composition was carried out between four identified date varieties e.g. Amhat, Hayany, Hagazy, Siwi and three of the Unknown date cultivars (seedling fruits) during the three stages of maturity Khalal, Semi-Rutab and Rutab.
In addition, study the aqueous extract of seedling date fruits (juice) was used as a raw- material for the production of ethanol by using of both baker’s yeast and the specific yeast strain Saccharomyces. cerevisiae ATCC4126. The effect of some fermentation conditions such as sugar concentration, pH and fermentation temperature on the obtained ethanol concentration was also studied.
The obtained results could be summarized as follow:-
I- physical properties of date fruits:
1- The fruit number/kg for unknown seedling dates varied from 71- 88, 76 - 96 and 82-102g during the three maturity stages Khalal, Semi-Rutab and Rutab, respectively. While the fruit number /kg ranged between 30 - 62, 36 - 69 and 40 -74g for date the identified varieties during the three maturity stages Khalal, Semi-Rutab and Rutab, respectively.
2- The unknown seedling dates characterized by decrement the fruit weight compared with the identified varieties. It ranged between for unknown seedling dates 11.36 - 14.08, 10.4 -13.16 and 9.80 - 12.19 g during the three maturity stages Khalal, Semi-Rutab and Rutab, respectively. While varied from 16.09 - 33.33, 14.49 -27.77 and 13.51 - 24.90g for date varieties, during the three maturity stages Khalal, Semi-Rutab and Rutab, respectively.
3-The pit percentage of the fruit for unknown seedling dates ranged between 16.34 -20.08, 16.80 - 20.17 and 16.33 - 20.50 % , while the pit percentage of the fruit for date varieties varied from 6.46 - 15.54, 4.95 - 15.18 and 4.52 - 14.59 %, during the three maturity stages Khalal, Semi-Rutab and Rutab, respectively.
4- No significant differences were observed between pH value for date varieties and unknown seedling dates during maturity stage under study .
II- Gross chemical composition of date fruits:
1-The unknown seedling dates characterized by lowest values of total sugar and reducing sugar and have slightly higher for crud fats, protein, ash and fiber compared with the identified date varieties
2-With development of maturity stages contents total sugars and reducing sugars of all date varieties were increased. Total sugars content for unknown seedling dates ranged between 48.67 - 65.01, 57.69 - 67.21 and 57.76 - 74.97%. While in date varieties varied from 71.26 - 76.40, 73.30 - 79.38 and 78.96 - 84.03%, during the three maturity stages Khalal, Semi-Rutab and Rutab, respectively.
3-The contents of ash, crude fiber, protein and fats were slightly decreased for all the studied dates with increasing of the maturity stage.
4- Data of macro-elements (K, Na, Mg and P) of the studied fruits revealed that the macro-elements gave the highest value in Khalal stage, decrease in Semi-Rutab and recorded the lowest value in Rutab stage. Potassium was the predominant elements in the three stage (644.6 - 1296.3 mg/100g), (642.7- 821.9 mg/100g) and (486.0 -633.8mg/100g) in Khalal, Semi-Rutab and Rutab stage, respectively. Phosphorus was the second major element (126.25 - 155.58 mg/100g ), (108.90 - 131.70 mg/100g) and (96.90-129.53 mg/100g) during the three maturity stages Khalal, Semi-Rutab and Rutab, respectively.
III- Ethanol production from seedling dates:
The suitability of seedling date extracts containing different sugar concentrations to ferment into ethanol was studied by two yeast strains. The first one is the commercial baker’s yeast and the second is the specific ethanol producer strain, S. cerevisiae ATCC4126.
The obtained results were as follow:
1-Maximum ethanol concentrations produced by baker’s yeast were 5.78; 6.50; 7.15; 7.22 and 7.04 % from date extracts containing 12, 14, 16, 18 and 20 % sugar, respectively.
2- Saccharomyces. cerevisiae ATCC4126 produced twice concentrations of ethanol from all the studied date extracts, compared with bakers yeast.
3- Date extract containing 18 % sugar was the most suitable for ethanol production. The quantities of ethanol produced by Saccharomyces. cerevisiae ATCC4126 were 12.23 %; 12.34 %; 12.44 %; 14.08 % and 13 % from date extract containing 12; 14; 16; 18 and 20% sugar, respectively. These concentrations were attained after 192 h. in case of juice containing 12 % sugar but after 168h. With juice containing higher sugar concentrations.
4- The optimum temperature for ethanol production ranged between 30 - 35°C and 25- 35°C for baker’s yeast and S. cerevisiae ATCC4126, respectively. Both yeast growth and alcohol production were completely inhibited at temperature higher than 40°C.
5- The most suitable pH values for the production of ethanol by baker’s yeast and Saccharomyces. cerevisiae ATCC4126 were 4.0 and 3.5,respectively.
6- Highly acidic date extracts with the lower pH values ‹3.0 were not suitable for yeast growth and ethanol production.
-from the results of this study, it could be concluded that fruits of (seedling date ) speared large quantities throughout Egypt, as well as fruit unfit for human consumption and the inedible date varieties as well as, the cull fruits from date- packing may. Good as a raw material (the source of essential sugars and cheap). For alcoholic fermentation or other valuable fermentation industries.