الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 119 |  |  |
| | | from | 119 | | |
Abstract
The present investigation was carried out in two successive seasons of 2008 and 2009 on “Hindi” and “Zibda” fruiting trees to study the effect of pre-harvest , ten days to harvest, spray with each of vitamin C solution at 1.0gL-1 “T1” and vitamin B12 solution at 1.0mgL-1 “T2”along with tap water to serve as control “Tс” on three physical and five chemical characteristics at harvest date and their changes throughout post-harvest cold storage period at 5±1°C and 80-85% RH for 30 day. These characteristics were measured either on intact fruits or determined in fruit juice and fresh peels. The tested trees were 20-year-old, almost uniform, apparently diseases free and grown in a commercial orchard located in Kafer Saker province, El-Sharkia governorate, Egypt. . Data obtained in this study could be summarized as follows: 1- Changes in fruit firmness: At harvest date, the highest firmness measurement was in fruits of “Hindi” cultivar from trees pre-harvest sprayed with vitamin C solution at 1.0gL-1 “T1”. The same was true in case of changes throughout cold storage period. The similar firmness degree on “Zibda” fruits was from trees under either “Tс” or “T2” treatment. 2- Changes in fruit weight loss percentage: The results showed that weight loss% of fruits of both cultivars were not significantly affected by either cultivar or treatment tested. Moreover, both antioxidant treatments had an effect during storage period lower than the control one with insignificant differences among them in both seasons. 3- Changes in chilling injury incidence: showed the incidence of “CI” symptoms, on stored fruits of the two tested cultivars under the antioxidant treatments, was started from the periodical measurement at 15th day and then gradually increased. Sprayed trees with vitamin C solution at 1.0gL-1 was the better treatment to minimize the incidence of “CI” symptoms especially for “Hindi” stored fruits, whereas the two antioxidant treatments almost had a mild effect on “Zibda” stored fruits till the end of storage period. 4- Changes in vitamin C (Ascorbic acid) content: Vitamin C treatment was the super among the tested ones to harvest “Hindi” fruits of the higher vitamin C content either at harvest date or throughout storage period. This treatment also succeeded to increase vitamin C in juice of “Zibda” stored fruits during cold storage period, whereas the vitamin B12 treatment was the superior in that respect at harvest date. 5-Changes in total acidity percentage: Both antioxidant treatments had a decreasing effect on juice acidity% of both cultivar fruits at harvest date and during cold storage period. Such decrease was higher in juice of “T1” fruits. 6- Changes in total soluble solids percentage: vitamin c caused an increase in juice TSS% at harvest date with different rates. It was in “Hindi” fruit juice better than in “Zibda” fruit juice. The same was true at the end of cold storage period. 7- Changes in total soluble solids/acid ratio: the highest for both cultivars was in juice of “T2” fruits followed by those of “T1” treatment at harvest date. At the end of cold storage period, such ratio in “Hindi” fruit juice was higher than in “Zibda” ones. 8- Changes in pigments content (β-carotene and chlorophylls) in fruit fresh peels: cleared that among the tested antioxidant treatments “T2” one was the best to harvest fruits of both cultivars contained the highest β-carotene content at harvest date. This super effect was also extended to chlorophylls content in fresh peels of “Hindi” fruits. During cold storage period all treatments under study caused an obvious increase on β-carotene and a decrease on chlorophylls content in fruit fresh peels of both cultivars as cold storage period advanced with different rates. The increasing effect on the former pigment in “Hindi” fruits due to the “T1” treatment was higher than “T2” one, whereas in “Zibda” fruits of both treatments had almost an equal effect. Moreover, the determined values were higher than those of “Tс” treatment. As for chlorophylls content, ”Hindi” fresh peels of the “T2” fruits recorded the least decrease during cold storage period. As for “Zibda” cultivar the fewest decrease was in fruit fresh peels of “T1” treatment. According to the results obtained in the current research, it could be concluded that cold storage of harvested fruits (at 5±1°C and 80-85%RH) plus pre-harvest spray with antioxidants solution can be succeeded to improve the quality of mango fruits of the two tested cultivars at harvest date and during cold storage with different rates. Concerning shelf life of stored fruits their effect was differed due to the different genotype of both cultivars under study. As for “Hindi” stored fruits, they continued at storage conditions till 15th day measurement without observing the incidence of chilling injury symptoms and could be extended to 20 day storage with light symptoms. In case of “Zibda” stored fruits, they showed a similar behavior as “Hindi” fruits till cold storage period of 15 day and afterward both antioxidant treatments succeeded to store fruits till the 30th day measurement (end of storage period) with almost mild chilling injury symptoms.