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Document Type |
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Thesis |
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Document Title |
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Evaluation of the antioxidant potential of some apple cultivars and the impact of thermal processing techniques تقييم القدرة المضادة للأكسدة لبعض أصناف التفاح وتأثير تقنيات المعاملة الحرارية |
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Subject |
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Biochemistry department |
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Document Language |
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Arabic |
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Abstract |
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Apples are one of the most frequently consumed fruits. The phenolic compounds in apples are responsible for most of the antioxidant activity of the fruit. In the Kingdom of Saudi Arabia (KSA), the commercial apple production is very restricted in some regions as Al-Taef, Al-Baha and Abha which growing some local apple cultivars. Therefore, KSA market depended mainly on imported apples. This study focused on the evaluation of the antioxidant capacities of imported apple cultivars (Granny smith, Golden Delicious (Italy), Red Delicious, Fuji, Gala, Straking Delicious and Golden Delicious (Syria)) and one local cultivar growing at Al-Taif region (Balady). A great variation in terms of total phenolic and flavenoid contents was observed among the peel and flesh of apple cultivars tested. The highest amount of total phenolics and flavenoids was observed for Balady apples. The evaluation of antioxidant activity of apple from different cultivars was conducted by several methods: Scavenging of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical, scavenging of 2,2'-azino-bis (3-ethylbenzo-thiazoline-6-sulfonic acid) (ABTS) and formation of phosphate/molybdenum complex. The phenolic content of peel and flesh from different cultivars of apples showed concentration dependent scavenging of DPPH and ABTS radicals and formation of phosphate/molybdenum complex. The results appeared high values of correlation coefficient (R2) between phenolic content of apples and antioxidant activity indicating the strong correlation. The antioxidant assay IC50 value (the inhibition concentration as µg phenolic content of the test sample that decrease 50% initial radical) was variable among different apple cultivars. Local apple cultivar Balady exhibited also high antioxidant activity. Phenolic content of Saudi apple cv. Balady was analyzed by GC-MS to determine its chemical composition that may contribute to its antioxidant activity. The Effect of microwave and heat treatments on phenolic content and antioxidant activity of the local cultivar Balady was evaluated. The total phenolic contents of peel and flesh were increased with increasing the time (20 Sec) of microwave (700 W) and at 30 sec the total phenolic content was decreased. In flesh, the DPPH assay IC50 value was decreased with increasing the time of microwave. There are no remarkable effect of heat treatment (80ºC) on the phenolic content of peel and flesh. The DPPH assay IC50 value was decreased with heat treatment of peel. The activities of antioxidant enzymes were screened in the crude extracts of the peel and flesh of the apple cultivars tested, which had high, moderate and low levels of peroxidase, catalase and polyphenoloxidase, respectively. The results indicated that the imported apples retained the most antioxidant activities and the Balady cultivar exhibited antioxidant capacity similar to the imported apples. Finally, this study will be supply information on the antioxidant activity of apples that benefits apples producers, nutritionists and consumers. |
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Supervisor |
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Prof. Dr. Saleh Ahmed Mohamed Ahmed |
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Thesis Type |
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Master Thesis |
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Publishing Year |
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1434 AH
2013 AD |
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Co-Supervisor |
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Dr. Mohamed Abdel-Ghani Awad |
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Added Date |
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Sunday, September 1, 2013 |
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Researchers
| فراس محمد السالك | Alsalik, Feras Mohame | Researcher | Master | |
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