Effect of gamma irradiation on the extraction yield, antioxidant, and antityrosinase activities of pistachio green hull extract

In this study, the antioxidant activity and tyrosinase inhibitory of non-irradiated and irradiated pistachio green hull (PGH) extracts were investigated. After irradiation of PGH by different doses of gamma ray (0, 10, 20, 30 and 40 kGy), their phenolic compounds were extracted by water. Antioxidant activities of extracts were examined by DPPH center dot and FRAP methods. The results showed that irradiation not only do not have negative effects on antioxidant activity but also it can increase the amount of total phenolic compounds of water extract in comparison with non-irradiated sample. Water extract of irradiated PGH at the dose of 30 kGy, showed the highest antioxidant activity in the DPPH center dot test with EC50 equal to 289.0 +/- 1.2 mu g/ml. Irradiated (30 kGy) and non-irradiated water extracts had the highest antityrosinase activities with IC50 of 10.8 +/- 1.1 and 11.9 +/- 1.2 mu g phenolic/ml, respectively. In addition, it was found that the water extract of irradiated PGH can prevent enzymatic browning in sliced raw potatoes. According to the antityrosinase potential of PGH extract, it may be suggested as an antibrowning agent in some foodstuffs or cosmetic products.