الفهرس 
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Abstract
Grapefruit sources of vitamin C and potassium and good source of iron, calcium, and other minerals. Pink and red varieties are high in betacarotene, a precursor of vitamin A. High in fiber, low in calories, Contain bioflavonoids and other plant chemicals that protect against cancer and heart disease.
The aim of this study was to investigate the effects of storage on those components, and through the following: To identify the chemical constituents of the fruits of grapefruit when combined directly, to identify the content of grapefruit flavonoids and vitamins and the effect of storage on those components, Examine the level of concentrations of antioxidants found in different parts of the fruits of grapefruit, compared to the levels required to maintain public health and Study the evolution of different chemical components in different parts of the fruit during storage at different temperatures.
Fruits were cleaned, washed with current fresh water and then air dried at roomtemperature. These fruits were stored either at room temperature (22± 2°C) or at refrigerator temperature (4±2°C) for different periods depending on the condition of fruits during the storage. Samples of fruits from each cultivar were randomly taken to determine the physical properties of the fruits. Samples of fruits were taken every week to determine:
Physical properties of fresh fruits in terms of fruit weight; peel weight; pulp weight and juice weight and Chemical composition of fresh fruits in terms of moisture content; sugar contents; protein contents; fat contents; and fiber contents. The PH values; total soluble solids (TSS, °Brix) tiratable acidity %; ascorbic acid content; and the TSS \ acidity ratio of the juice were determined.
The obtained results of the present study could be summarized in the following points:
1- Data revealed that the Marsh cultivar showed 12.42, 12.78, and 9.78 % dry mater in peel, pulp and juice, where as the Duncan cultivar showed 12.62, 10.65, and 7.65 % for the same components which Marsh showed higher than Duncan.
2- Data also revealed that the Marsh cultivar had 24.48 and 35.29 % as total sugars in the peel and in the pulp, while as the Duncan cultivars showed 22.35 and 35.31 %, The non-reducing sugars, however, represented the most dominant sugars in the total sugars, being higher in the pulp than in the peel. The Marsh cultivar had 16.59 and 30.44 %, while the Duncan cultivar showed 16.32 and 26.48 % in peels and pulps, while the Marsh cultivar contained 7.89 and 4.85 and the Duncan cultivar contained 4.36 and 8.83 % reducing sugars in peels and pulps.
3- Data also revealed the Duncan cultivar showed higher protein content than the Marsh cultivar in both peels and pulps. Duncan cultivar had 18.48 and 23.38 % protein, where as the Marsh cultivar showed 14.33 and 20.89 % in peels and pulps.
4- Both cultivars, showed little fat contents as compared to other contents. The Marsh cultivar had 2.09 and 3.7 % and the Duncan cultivar had 2.38 and 3.90 % in both peels and pulps.
5- The fiber contents in both cultivars represented the most dominant component in the dry matter as compared to the other components such as sugars, proteins and fats. However, the Marsh cultivar showed higher content than Duncan cultivar.
6- Data also showed that the Marsh cultivar had a higher content of total soluble solids (TSS) than Duncan cultivars. The juice of Marsh had 10 0Brix compared to 8 0Brix in juice of Duncan cultivar. The PH value and the total acidity % in Marsh juice were 3.29 and 2.21 % compared to 3.4 and 3.37 %
7- Data also revealed that Marsh cultivar showed higher contents of ascorbic acid in peel, pulp, and juice than in Duncan cultivar. Nevertheless, the juice had the highest ascorbic acid content as compared to peels and pulps in both cultivars. The Marsh peels, pulps and juice contained 30.66, 35.33 and 60.02 mg / 100 ml juice as compared to 25.33, 30.36 and 55.65 in Duncan.
8- Data revealed that the fresh fruit weights of both cultivars decreased in similar way as the storage time increased. The fresh fruit weights of Marsh cultivar decreased at the start of storage whereas the Duncan cultivar decreased grams at the end of storage for six weeks at temperature room. The fresh weight of both cultivar decreased by approximately the same percentage 37.97%. Data revealed that the fresh fruit weights of both cultivars decreased in similar way as the storage time increased (temperature room, 40C).
9- Data also revealed that the fresh weight of peel from both cultivars stored at room temperature and 40C also decreased in similar way as the storage time increased, They decreased by 28.55% and 28.62% at the end of storage. Data also revealed that the fresh weight of pulp from both cultivars stored at room temperature and 40C also decreased in similar way as the storage time increased They increased by 72.97% and 72.21% at the end of storage. Data also revealed that the juice volume from both cultivars stored at room temperature and 40C also decreased in similar way as the storage time increased, They decreased by 15% and 24.4% at the end of storage.
10- Data revealed that the dry matter contents of peels and pulps increased as the storage time continued up to six weeks. However, the dry matter contents of Red Duncan peels and that of pulps were higher than their corresponding of White Marsh, It increased by 4.77 folds. While the dry matter of the Red Duncan pulps increased after six weeks of storage. It increased by 5.11 folds.
11- These results suggested that the peels of grapefruit had dry matter contents higher than of pulps. Contrary to dry matter contents, all the chemical components such as total sugars, reducing and non-reducing sugars, proteins and fat contents decreased as the storage time increased up to six weeks at room temperature.
12- Data revealed that grapefruit pulps, as expected, had higher total sugars than that of peels, Data also showed that the both reducing sugars decreased with increasing the storage time. Nevertheless, the non-reducing sugars, however, were higher than the reducing sugars in both peels and pulps. Nevertheless, the reducing sugars in the Red Duncan pulps were higher than in the peels. On the other hand the reducing sugars were higher in the peels of the White Marsh than that in pulps. The non-reducing sugars of the While Marsh pulp, however, were higher than that the Red Duncan pulps and vice – versa for the Red Duncan peels. The non-reducing sugars, nevertheless, decreased as the storage time increased up to six weeks
13- Results of protein content suggest that the protein loss from pulps was higher than that from peels in both cultivars. However, the loss of protein from the Red Duncan cultivars was faster and greater than that of the White Marsh cultivars. While the data of fat content suggest that the pulps of the Red Duncan cultivars showed higher fat loss than that of Marsh where as, the peels of the both cultivars showed approximately the same fat loss during storage for six weeks. While the results of fiber content of peels were greater than that of pulps in both cultivars. And also, the fiber contents of both pulps and peels of the Red Duncan were greater than their corresponding of the White Marsh cultivars and suggest that the increased in fiber contents of pulps was higher than that of peels in both cultivars.
14- The ascorbic acid (vitamin C) contents markedly decreased with storage of the Marsh pulps and also decreased of Duncan pulps. These results suggest that the loss of ascorbic acid contents from the Marsh cultivars (pulps and peels) was greater than that of Duncan cultivars. The end Data showed that the above components were similarly affected by cold storage as those affected by storage at room temperature, however, the effects was augmented by cold storage of grapefruit.
15- The juice of the two cultivars could not stand the storage at room temperature for only two days while Effects of storage at 40 C for four weeks on the juice components of White Marsh and Red Duncan in terms of total soluble solids (TSS, Birx), PH, total acidity (%), ascorbic acid (mg /100 ml juice) and dry matter %. Data revealed that the juice of the White Marsh grapefruit had a higher TSS than that of the Red Duncan at the start of the storage when the end of storage. The pH values of the Marsh juice and the Red Duncan juice decreased with the same percentage (26%) after storage for three weeks. Total acidity (%) also decreased by 11.6 % at the Marsh when the Duncan the decreased by 29.9 %
16- The ascorbic acid content of the White Marsh juice decreased by 34.4 %, and that of the Red Duncan decreased by 38.5 % after storage for three weeks at 40C. Dry matter contents of the juice increased of both cultivars. These results revealed that the Red Duncan juice was more affected by storage than that juice of the White Marsh.
17- Data showed the antioxidant concentrations from peels and pulps of Marsh and Duncan grapefruit that peels of both cultivars contained higher concentrations of antioxidants than that of the pulps at the start of the storage. The data also revealed that the antioxidant concentrations decreased as the storage time continued up to six weeks. The data also revealed that the antioxidant concentrations decreased as the storage time continued up to six weeks. These result revealed that antioxidant activity increased as the antioxidant concentration increased at the start of the storage time. However, the vice-versa occurred at the end of the storage time since as the antioxidant concentration decreased, the antioxidant activity increased. For instance, the antioxidant activity of Duncan Pulp was the lowest at the start of the storage it showed the highest activity at the end of storage time as compared to others.
18- During the cold storage these concentrations increased with increasing the time of storage. The increase of antioxidant concentration of the Marsh peels and pulps were higher than their corresponding of Duncan cultivar. The antioxidant concentration of the Marsh peels increased by 99.3 % vs. 89.6 % for the Duncan peels and increased by 120.5 for Marsh pulp vs. only 35.5 % for the Duncan pulp. These results suggested that the Marsh cultivar was more affected by the cold storage than the Duncan cultivar. Data revealed that the antioxidant activity for all components increased during the cold storage for four weeks. The Marsh peels, however, showed the highest antioxidant activity (0.569 %) as compared to other components followed by the Duncan peels (0.462 %), Marsh pulp (0.363 %) and finally the Duncan pulp (0.262 %) at the start of cold storage. on the other hand, the Marsh pulp showed a higher antioxidant activity at the start than that of the Duncan pulps, the vice-verse occurred at the end of the storage since the latter showed higher activity than the former.
19- Data revealed that Marsh cultivar had higher TPC than that found in the Duncan cultivars. The Marsh peels, however, showed the highest TPC 1.293 % and the pulp had 1.015 % as compared to 0.839 in Ruby peels and 0.553 % in the Duncan pulps at the start of the storage. The TPC, increased as the storage time continued up to six weeks. The TPC of the Marsh peels was the increased. The TPC of Duncan peels, however, was the most affected. It increased from 0.839 to 3.354 % (increased by 299.8 %). Data revealed that the two cultivars showed different behaviour during cold storage as compared to that stored at room temperature. The Duncan peels showed, however, the highest TPC (3.272 %) at the start of cold storage compared to 1.690 % for the Marsh peels. The Marsh pulps contained 1.284 compared to 0.807 % for the Duncan pulps.
20- Data revealed that Duncan cultivar had higher flavonoids than that found in the Marsh cultivars. The Duncan peels showed the highest flavonoids 0.097 % and the pulp had 0.079 % as compared to 0.077 in Marsh peels and 0.068 % in the Marsh pulps at the start of the storage. The flavonoid of Duncan peels, however, was the most affected. The flavonoids of the Marsh pulps increased by 86.76 % as compared to 77.22 % (Duncan Pulp) at the end of storage. Data revealed that the two cultivars showed different behavior during cold storage as compared to that stored at room temperature. . Data also showed that the flavonoids decreased in the increasing the storage time up to four weeks.