الفهرس 
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Abstract
This investigation aimed to study the effect of paraffin oil and polyethylene bags used as separately or in combination on the quality of ”Manfalouty” and ”Hegazi” pomegranate fruits during storage. Pomegranate fruits were collected at maturity stage from the orchard of Pomology Department, Faculty of Agriculture, Assiut University during two seasons 2012 and 2013. Harvested fruits were directly transferred to the laboratory in the same faculty.
The maturity signs of the fruit were that the peel is red color and shiny, full opening of the calyx, juice of arils is deep red colored and T.S.S/TA for juice arils (12/1). The fruits were selected for uniformity of shape, size and free of physical damage and infections.
Experimental fruits were divided into four similar groups. Each group was subjected to one of the following treatments:-
1- Control group (untreated fruits), T1.
2- Packing with polyethylene bags, T2
3- Coating with thin layer of paraffin oil, T3.
4- Coating with thin layer of paraffin oil + packing in polyethylene bags,T4
Each treatment was replicated three times. Half of the experimental fruits were stored at (5ºC±1) and (90%±5) relative humidity and the other half was stored at room temperature (22±5C°). Changes in some physical and chemical fruits properties were determined every 15 days interval. Some fruits from each treatment were selected to determine both weight loss and decay percentage during cold storage and room temperature condition.
*Some physical and chemical properties were measured as follows:
A- Physical properties:-
Weight loss % , decay% and juice volume of 100(g) arils.
B- Chemical properties
Total soluble solids (T.S.S), total acidity (TA) and T.S.S/acid ratio.
The results could be summarized as follows:
A- Physical properties:
1- Weight loss:
Generally, the weight loss % of Manfalouty and Hegazi fruits increased gradually with the progress of storage period during both storage condition. In the first season under room temperature, paraffin oil treatment alone or in combination with polyethylene pack significantly reduced the weight loss, for Manfalouty and Hegazi fruits. Also, in the second season, combination between paraffin oil and polyethylene pack was the leader in reduction of weight loss in Manfalouty and Hegazi cvs. At the end of cold storage period after 90 days, the polyethylene pack alone or in combination with paraffin oil, significantly reduced the weight loss % in both successive seasons, compared with paraffin and control for Manfalouty fruits. Concerning Hegazi fruits under cold storage, paraffin oil alone in 2012 or combined with polyethylene bags in 2013 had the best effect on reduction the weight loss %.
2- Decay
The decay % in Manfalouty fruits increased with the prolonging of storage period under both storage conditions in 2012 and 2013 seasons. At the end of storage, the highest percentage of decay was found in untreated fruits (control) compared with other treatments whereas, the lowest value of decay % was obtained by Paraffin oil + polyethylene bags during room temperature and cold storage, in the two investigated seasons. The decay % of Hegazi fruits as affected by the applied treatments took approximately the same trend as those of Manfalouty fruits. All treatments reduced the decay % of Hegazi fruits as compared with untreated one (control).
3- Juice volume of 100 (g) arils
The juice volume of ”Manfaluty” pomegranate fruits decreased with the storage period increasing for all treatments during both tested seasons. Significant differences were found between treatments and control in different storage conditions during both investigated seasons. Under room temperature and cold storage condition, paraffin oil + polyethylene bags treatment gave the best effect of preserving the reduction of juice volume at the end of storage, in two successive seasons.
Similar findings were found from the obtained results of Hegazi fruits concerning the tested treatments during both 2012 and 2013 seasons. All treatments had significantly higher juice volume / 100 g arils of Hegazi fruits at the end of both storage conditions compared with untreated fruits (control). In addition, the highest values of juice volume were found in the treated fruits with paraffin oil + polyethylene bags, while the lowest values of juice volume recorded in the control fruits.
Chemical Properties
1-T.S.S:-
Generally, T.S.S percentage gradually increased in all stored fruits of Manfalouty and Hegazi cvs. with the extending the storage period until 45 days at room temperature and 90 days under cold storage. Moreover, at the end of storage period the highest values of T.S.S content were found in the juice of untreated fruits (control) at room temperature and at cold storage during both investigated seasons. On the other hand, the treated fruits with paraffin oil + polyethylene bags had significantly the lowest values of T.S.S % as compared with other treatments.
2- Total acidity:-
At room temperature, there were insignificant differences between polyethylene bags, paraffin oil and control while, paraffin oil + polyethylene bags had significant lower acidity % compared with the other treatment and control. The highest values were found in control fruits of Manfalouty and Hegazi cvs. in the two successive seasons. Similar tendency was observed during cold storage condition in the two tested seasons.
3- T.S.S/Acid ratio:-
TSS/acid ratio in Manfalouty fruits increased by the prolonging the storage period in 2012 and 2013 seasons under both storage conditions. In room temperature, higher values of T.S.S/acid ratio in the stored fruits were found by paraffin oil+ polyethylene bags compared with the other treatments and control while, the lowest values were found by control fruits during both seasons. The same trend was observed at the end of cold storage. The results of T.S.S/acid ratio of Hegazi fruits took approximately similar tendency as those of Manfalouty cv. under both storage conditions during 2012 and 2013 seasons.
Conclusion:-
This study illustrated that, Manfaluty and Hegazi pomegranate fruits can be stored for about 45 days in room temperature and 90 days in cold storage. When polyethylene bags and paraffin oil are used separately they can retains the quality of fruits. Whereas, the combination between polyethylene and paraffin oil gave the best positive effect on prolonging the storage period with best fruits quality.