الفهرس 
ِِِAcknowledgementOnly 14 pages are availabe for public view
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Abstract
Egypt lies in the first largest date producer among the world countries (1.465.030 tons). There is a gradual increase of Egyptian date production in the last period (FAO, 2017). Besides, there is a great amount of seeding date palm; some of them are desirable for fruit qualities. This study was carried out on one of the most famous and important date cultivar; Saidy (semi dry variety) in Egypt. There is a large amount of the low quality fruits was found during the sorting and packing process in the date production factory. These fruits and the surplus date yield are usually used in the preparation of the different products such as date paste.
This study was conducted on Saidy date fruits ( the sand grade and low quality) these fruits were prepared to date paste in order to assess the influence of addition citric acid only ascorbic acid only, sodium metabisulfite only, citric acid + sodium metabisulfite, ascorbic acid + sodium metabisulfite.
The irradiation process with 2KGy was applied on the treated date paste with citric acid only, ascorbic acid only and sodium metabisulfite only compared with the control. All date paste samples were stored at room and refrigerator temperatures up to six months. All date paste were evaluated for their physical properties, chemical composition, microbial counts and sensory attributes. Also, the effect of the replacing sugar by date paste in preparation of some bakery products on their chemical composition and sensory quality.
This study led to the following conclusions:
1. Physical characteristics of Saidy date fruits.
The number of Saidy date fruits/kg was 88. Consequently, the mean weight of fruits flesh and pits were 11.36, 9.69 and 1.30, respectively. Meanwhile, the percentage of flesh and pits weight was 87.92 and12.08%, respectively and the flesh / pits ratio of fruits were 7.45. The TSS, pH value and color (OD) of Saidy fruits were 90.01%, 6.20 and 0.47, respectively.
2. Chemical composition of Saidy date fruits.
The chemical composition of Saidy date fruits; the moisture, sugars (total, reducing and non-reducing sugars), crude protein, crude fiber, ash, crude fat and total acidity values were 14.51%, (81.94, 76.12, 5.82%), 2.94, 3.17, 2.80, 1.83 and 0.18%, respectively. The total phenolics content was 296.84 mg GAE/100g.
3. Minerals content of Saidy date fruits:
Data revealed that the potassium, sodium, magnesium, calcium, iron, zinc and copper content were 598.36, 22.89, 60.17, 7.90, 1.56, 0.63 and 0.42 mg/100g dry weight, respectively.
4. Effect of treatments on physical characters of Saidy date pastes during storage:
4.1. pH value:
Results showed that the pH values of all date paste samples were decreased during storage periods. The decreasing in the pH values of the stored date paste samples in the refrigeration was lower than that of the stored at room temperature. The lowest pH value was recorded in citric acid date paste followed by ascorbic acid + sodium metabisulfite at zero time and the end storage time at room temperature. The lowest pH value was observed in the irradiated date paste contained citric acid only at zero time and after six months of storage at room and refrigerator temperatures
4.2. Color (OD):
Data of color as optical density (OD) of Saidy date paste showed that the color values increased during storage as the storage and time temperature increased. All treated date paste recorded (OD) values lower than that of the untreated sample (control) during storage periods. The best color (lowest OD value, 0.883) was found in the formulated date paste by ascorbic acid + sodium metabisulfite after 6 month of storage in the refrigeration followed by at room. The irradiated ascorbic acid date paste sample had the best color (lowest OD value), during storage.
There were high significant differences (p0.05) between all Saidy date paste samples in their color at different storage places, treatments storage periods and the interactions.
5. Effect of treatments on chemical composition of Saidy date pastes
during storage
5.1. Moisture content:
The results revealed that the moisture content of Saidy date pastes (the control and treated samples) decreased during storage. The loss in moisture count of all date paste samples stored in the refrigeration was lower than that lifted at room temperature. The loss rate of moisture count of the treated by ascorbic acid + sodium metabisulfite was 10.70% and 1.52% after 6months of storage at room and refrigeration, respectively. Meanwhile, the irradiated ascorbic acid date paste sample had the lowest decrease in moisture content among all samples; the rate of decreasing was 6.33 and 3.36% at room and refrigerator temperature, respectively after six months.
5.2. Crude protein:
The crude protein content of Saidy date pastes (the control and treated samples) was decreased during storage periods. The reduction level of crude protein content at room temperature was higher than that at refrigeration storage for all date paste. The lowest decreasing rate of protein content was found in ascorbic + sodium metabisulfite sample 20.86 and 9.71% at room and refrigerator temperatures, respectively after six months. Meanwhile, the lowest decrease in crude protein content among the treated date paste was found in the irradiated ascorbic acid, it was 15.32 and 6.31%, at room and refrigerator temperatures respectively after six months.
5.3. Crude fiber: