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العنوان
Chemical and Technological Studies for Improvement of Date Syrup (Dibs) Quality /
المؤلف
Hamam, Samar Hassan Abdalla.
هيئة الاعداد
باحث / سمر حسن عبد الله هنلم
مشرف / بلبل رمضان رمضان
مناقش / سامى ابراهيم الصياد
مناقش / محمد عبد الحميد حسن
الموضوع
Dates.
تاريخ النشر
2018.
عدد الصفحات
115 p. :
اللغة
الإنجليزية
الدرجة
ماجستير
التخصص
علوم وتكنولوجيا الأغذية
الناشر
تاريخ الإجازة
10/8/2019
مكان الإجازة
جامعة أسيوط - كلية الزراعة - Food Science & Technology
الفهرس
Only 14 pages are availabe for public view

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from 115

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 considered as the first country of the top ten date producers in world (1,694,813 tons), it produces 18% from the overall international produce of date and 23% from the Arab world produce (FAO, 2016). However, a significant portion of date are wasted in date producing countries (e.g. 30% loss of total produce) due to its inferior quality, damage, and undersized fruit of unattractive appearance, The low quality dates are a rich source of carbohydrates composed mainly of sugars and dietary fibres and are safe for human consumption. Owing to their composition, low quality dates were also used for preparation of some products with high value-added. The obtained results could be summarized as follow:
I- Physical characteristics :1-The fruits number/kg were 102, 159 and 300 for Saidy , Tamr and Manthor , respectively. and the Saidy date had the highest mean fruit weight (13.30g) followed by Tamr (6.80g) and Manthor (3.70g).2-The mean weights of flesh were (9.22, 5.86, 2.85g) and pit (1.34, 1.38, 0.80g) in Saidy, Tamr and Manthor date, respectively. 3-Tamr date had the highest percentage of fruit flesh followed by Manthor and Saidy (83.50, 77.00 and 69.30%, respectively). Beside, Saidy fruits recorded the highest flesh/pit ratio (6.90).4-The highest pit percentage was recorded in Manthor date (21.6) followed by Tamr (20.30) and Saidy (10.10).5-The highest fruit length mean was 3.30cm of Saidy followed by Tamr (3.10cm) and Manthor (3.00cm). Besides, the geometric mean diameter was 1.90, 1.70 and 1.60cm of Saidy, Tamr and Manthor date fruits, respectively.6-The mite infestation percentage was highest in Tamr fruits (11%) followed by Manthor (6%) and Saidy (2%) fruits. II- Gross chemical composition of fruits ((dwb), except moisture):1-The moisture content of the studied date fruits was 13.21, 10.72 and 8.12% for Saidy , Tamr and Manthor date fruits, respectively.2-Saidy date fruits had the highest concentration of the total, reducing and non-reducing sugars were (81.50, 75.90 and 50.50%) for Saidy, followed by Tamr (41.70, 57.70 , 40.50%) and Manthor (39.80, 18.20 , 10.00% dwb) fruits. 3-The crude protein varied from 1.81 to 1.93% dwb for Manthor and Saidy, respectively.4-Crude fiber ranged from 2.44% for Saidy to 4.11% dwb for Manthor.5-The ash content of the Saidy , Tamr and Manthor fruits was 1.73, 1.79 and 2.50% dwb, respectively.6-The crude fat content of Saidy , Tamr and Manthor date flesh was 1.39, 1.24 and 1.21% dwb, respectively.7- Saidy date flesh recorded the lowest total acidity values (0.14) of the studied date fruits flesh of Saidy, while Manthor flesh had the highest value (0.22) (% as malic acid).
8- Data of (K, Na, and Mg) revealed that potassium was the predominant macro elements recorded 109.37, 142.52 and 157.37mg/100g dwb for the Saidy , Tamr and Manthor fruits, respectively. Also, found that date was rich in the most important elements such as iron and zenic III- Effect of treatments on date juice properties:a- Effect of enzyme treatments on extracted date juice : 1-from the data it could be concluded that the enzymatic extraction was the most treatment of juice from Saidy, dates recorded high solids recovery and good clarity. The optimum conditions were mixing date pulp with water (1:3), then adding 1% of pectinase enzyme and incubating the mixture ( with continuous agitating at 50 °C for 60 min) and this is the best enzymatic treatments which applied on Tamr and Manthor date fruits. Whereas, pectinase enzyme treatment leads to breakdown of linkage between pectin and cellulose, solubilizing the cell wall polysaccharides , releasing the juices which flow without the application of pressure as free-run.2-from the obtained results, it was clear that as the enzyme dose and incubation time increased, juice extraction improved and more of the TSS could be recovered.3-The enzyme treatment of date pulp greatly improved the clarity, viscosity, turbidity and color as absorbance at 420 nm of the resulted juice.b- Effect of the activated carbon treatments on color removal of dates juice : 1-After filtration, the filtered matter was treated with different concentration of carbon and the mixture heated to 40, 50, 60 and 70 °C for different times 15, 30, 45, 60, 75 and 90 min.2-The result showed that 1.50% of carbon at 60 °C for 45 min gave the highest removal of juice color. It was the best treatments, so it was applied on both Tamr and Manthor juicesIII- physicochemical composition of dibs:1-Saidy dibs :1-The TSS of Saidy dibs produced from pectinase extracted juice, clarified juice by carbon and control were 72.00 , 71.00 and 70.00% on wet weight basis .
2- It was found that Saidy dibs sample produced from enzymic extraction juice contained higher total sugars level compared with control sample. 3-Acidity values of dibs samples obtained from enzymic extraction juice, clarified juice by carbon and control sample were 0.90 , 0.13 and 0.39%, respectively. Moreover their pH values were 5.14 , 5.26 and 5.34, respectively. The higher acidity values as well as slightly lower pH values found in dibs samples produced from pectinase extracted juice could be due to the increase in carboxylic groups liberated during the degradation of pectin by the enzyme action .4- The untreated dibs sample (control) showed high browning index value ( A at 420 nm ) as 0.77 compared with dibs of the treated sample withenzyme which was 0.52 and dibis sample produced from clarified juice (0.36) .5- It was observed that the clarity of dibs sample prepared from carbon clarified juice and the control sample was 71.37 and 60.39%, respectively. On the other hand dibs samples of the enzyme treatment had the highest clarity value (79.43%), this due to the degradation of pectic substances during enzymic extraction.2-Tamr and Manthor dibs :
The results showed similar trends to that found with Saidy dibs regarding effects of juice enzyme extraction and clarification by activated carbon and concentration on the physicochemical characteristics of Tamr and Manthor dibs.
1- Total soluble solids content of Tamr and Manthor dibis produced from enzyme extracted juices , carbon clarified juices and control ( untreated juices ) was 72.5, 70.0 and 68.5% for Tamr dibs, 72.0, 70.0 and 68.0 for Manthor dibs, respectively.2-Total sugars contents of Tamr and Manthor dibs produced from enzyme extracted juices were 63.00 and 72.67%, respectively. While, their total sugar of produced from carbon clarified juices were 55.80 and 54.26%, respectively and for control samples it were 60.43 and 57.69%, respectively. Also, reducing sugars determined by 53.13, 48.00 and 51.00% for Tamr dibs produced from enzyme extracted juices, clarified juices and control, respectively. However, it were 60.77, 43.97 and 49.04%, respectively for Manthor dibs. Tamr and Manthor dibs produced from enzyme extracted juices recorded higher reducing sugars contents compared with untreated samples.3-Acidity values of dibs produced from enzyme treated samples were found to be higher than that of samples obtained from clarified juices and control samples.4-The degradation of pectic substances during enzymatic extracted greatly improved the clarity of Tamr and Manthor dibs samples obtained from enzyme extracted juices.
5- Light color of Tamr and Manthor dibs obtained from clarified juices, which confirmed by the lower values of ( A at 420 nm) 0.31 and 0.72, respectively as compared with higher values (1.46-1.07) of control samples.<from the obtained results of this study, it could be concluded that date juice could be treat with enzymatic treatments and/or clarified by the activated carbon to produce date syrup (Dibs) with good properties and high quality from second grade date fruits and this will gave it a high economic and value-added.