Phenolic compounds, vitamin C, and the antioxidant activity of wasted parts of citrus (orange, lemon, and grapefruit) fruits were investigated. Ethanolic extracts from whole fruit, peel, and pulp containing seeds of each type of citruses were prepared. Within each type of citrus, results revealed that peels contained a higher amount of phenolic compound, flavonoids, vitamin C, and antioxidant activity than those of their inner wasted parts (pulp and seeds). Peels of grapefruit had the highest total phenolic content followed by lemon and orange, which was found to be 77.3, 49.8, and 35.6 mg of gallic acid equivalent/g of peels, respectively. In contrast, orange peels contain the highest amount of flavonoids (83.3 mg of catechin equivalent/g) and vitamin C (110.4 mg/100 g) compared to the peels of the other citrus fruit used in this study. In general, the high content of antioxidant capacity and activity of citrus waste, particularly the peels, indicated that they may impart health and nutritional benefit when involving in the food industry as a natural antioxidant.

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This study investigated the free fatty acids, fatty acid profile, total phenolics, and antioxidant activity of sesame seed oil extracted from γ-irradiated seeds and the decontamination effects of the treatment on fungal incidence in the seeds. Gamma irradiation reduced (P ≤ 0.05) fungal growth and colony forming units of sesame seeds in a dose-dependent manner. The free fatty acid content of sesame oil decreased (P ≤ 0.05) in irradiated samples compared to non-radiated controls, but there was no difference (P ≥ 0.05) between samples treated at doses ≥ 1.0 kGy. A concomitant (P ≤ 0.05) increase in total phenolic and scavenging activity was observed in the oil extracted from γ-irradiated sesame seeds in comparison with non-radiated samples, while free fatty acid (FFA) content decreased. The results obtained in the present study demonstrate that γ-irradiation at low doses can be used as an effective post-harvest preservation method for sesame seeds without a major effect on the quality of sesame oil.