الفهرس 
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Abstract
The present study dealt with investigates of biochemical properties of some natural antioxidants such as yellow golden berry fruits (Physalis peruviana l.), three different colours of pepper fruits (Capsicum annum l.), grape seeds (Vitis vinifera l.) and peel of pomegranate (Punica granatum l.). Methanolic extracts were prepared from both fresh pepper fruits and air dried of the other samples. Total polyphenol and flavonoids contents were estimated. Methanolic extracts of grape seeds and pomegranate peels showed the highest amounts of total polyphenols were 200.48 and 159.59 mg GAE/g, respectively. However, grape seeds and physalis fruits exhibited the highest value of total flavonoids 45.76 and 42.71 mg QE/g. Total antioxidant activity was evaluated by using three methods which were: total antioxidant capacity (phosphomolybdenum assay), DPPH radical scavenging assay and reducing power assay. The results obtained by phosphomolybdenum assay showed extracts of grape seeds and pomegranate peels have the strongest antioxidant capacity as 762.7273 and 701.515 mg AAE/g, while yellow pepper extract showed the lowest antioxidant capacity (113.03 mg AAE/g). In the same trend, grape seeds and pomegranate peels extracts exhibited the highest scavenging activity by DPPH radical scavenging assay and the lowest IC50 value were 9 and 71.6 µg/ml. High reducing power was recorded for grape seeds and pomegranate peels extracts, while red pepper and physalis fruits had the lowest reducing power. Effect of edible coating containing gum arabic and gum arabic mixed with polyvinylpyrrolidone or pomegranate peel extract on antioxidant activity of tomato (Solanum lycopersicum l.) stored for 20 days at room temperature was studied.