الفهرس 
ACKNOWLEDGEMENT
Physical propertiesOnly 14 pages are availabe for public view
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Abstract
This study was conducted during two successive seasons of 2015 and 2016 on Red Roomy grapes grown in the orchard of Pomology Department, Faculty of Agriculture, Assiut University. At the harvest date many of clusters were collected and selected for uniformity of size and shape and absence of visible defects and were directly transferred to the laboratory of pomology Department, Faculty of Agriculture, Assiut University.
The collected clusters were divided into three similar groups. Each group (consisted of 18 clusters) was subjected to one of the following treatments:
1- Control (distilled water)
2- Chitosan 2%
3- Clove oil 3%
The clusters of all treatments were dipped for 60 second in the solution of each treatment, and airs dried, and then were stored at 0±2°C and 90-95 R.H.
The parameters of storage grape clusters were determined periodically at weekly interval as follow:
A-Physical properties:-
A-1 Weight loss (%).
A-2 Decay (%).
B-Chemical properties:-
B-1Total soluble solids percentage (T.S.S %)
B-2 Total acidity (%)
B-3 T.S.S/acid ratio
B-4 Reducing sugar (%)
B-5 Ascorbic acid (Vit. C) (Mg/100ml juice).
The obtained results could be summarized as follow:
Physical properties:-
Weight loss (%):-
Generally the weight loss significantly increased with the prolonging of storage period in the two successive seasons. Moreover the maximum values of weight loss (%) were recorded at end of storage period for all treatments. The result showed also that both of chitosan and clove oil coating significantly decreased the percentage of weight loss as compared with untreated grapes (control) during both tested seasons. The highest values of weight loss (%) were found in the untreated (control) grapes at the end of storage period during both 2015 and 2016 seasons. On the other hand, the lowest values of weight loss (%) were recorded in the grapes coated with chitosan during the first season, while clove oil treatment gave the lowest values of weight loss (%) during the second season 2016.
Decay (%):-
Generally the percentage of decay gradually and significantly increased by the prolonging the storage period and reached its maximum values at the end this period for all treatments during both 2015 and 2016 seasons.
The highest values of decay percentage of grapes were recorded in the untreated grapes (control) during both seasons 2015and 2016.Moreover the lowest values of decay (%) were found in the coated grapes with chitosan in the first season 2015, while the coated grapes with clove oil had the lowest value of decay during the second season 2016.
Chemical properties:-
Total soluble solids percentage (T.S.S %):-
T.S.S content (%) significantly increasing with extending the storage period and reached the maximum values at the end of storage period for all treatments during both experimental seasons.
Moreover the highest values of T.S.S at the end of storage period were recorded in coated fruits with chitosan, while the untreated fruits (control) contained the lowest values of T.S.S at the end of storage period during both tested seasons. The increment of T.S.S (%) with the progress of storage period may be attributed to the water loss increasing during storage.
Total acidity (%):-
Total acidity content gradually decreased for all treatments with the begging of storage period, and then it significantly increased (except the control 2016) and reached its maximum values at the end of storage period during both tested seasons. Both of chitosan and clove oil coating treatments significantly increased the acidity content in the grapes comparing with untreated grapes (control) during both experimental seasons. The lowest values of acidity percentages were measured in the uncoated grapes (control) at the end of storage period while the coated grapes with clove oil contained the highest values of acidity during both investigated seasons.
T.S.S/acid ratio:-
The ratio of T.S.S/acidity gradually and significantly increased up to the fourth week in 2015 and the second week in 2016, and then it decreased gradually until the end of storage period during both experimental seasons. At the end of storage period the uncoated grapes (control) contained the highest values of T.S.S/acid ratio. On the other hand the coated grapes with clove oil had the lowest values of T.S.S/acid ratio during both seasons 2015 and 2016.
Reducing sugar (%):-
Reducing sugar content in the grapes of all treatment taok the same trend of T.S.S content during both 2015 and 2016 seasons. Red. Sug (%) gradually increased by the prolonging of storage period for all used treatments and reached its maximum values at the end of storage during both tested seasons. The grapes coated with chitosan had the highest values of reducing sugar at the end of storage duration comparing with clove oil and control treatments while, the lowest values of reducing sugar content (%) were found in the untreated grapes (control) at the end of storage period during both tasted seasons.
Ascorbic acid (Vit.C) (mg/100ml juice):-
General the results show that the grapes content of Vit.C (mg/100ml) for all treatment took approximately similar tendency in most cases during both investigated seasons. Moreover the obtained data indicated that the coated grapes with clove oil contained the lowest values of Vit.C at the end of storage period, while the highest values of Vit.C content were measured in untreated grapes (control) in the first season and in the coated grapes with chitosan at the end of storage period in the second season.
Recommendation:-
It could be recommended that coating of Red Roomy grapes with chitosan or clove oil could extend the storage period of these grapes under cold storage for about 1-2 weeks with maintaining fruit quality by reducing the weight loss and decay percentage.