Determination of the bioaccessibility and antidiabetic properties of pomegranate peels

In recent years, consumption of pomegranate products have increased with the understanding of its benefits to human health, and pomegranate peel has become one of the most common wastes in the food industry. In this study, some physicochemical, antioxidant, in vitro bioaccessibility and antidiabetic properties of peels of Hicaz, Devedişi, and Zivzik pomegranate varieties were determined. The average values of total phenolic contents, total flavonoid contents, Punicalagin A, Punicalagin B, Ellagic acid, DPPH and ABTS of pomegranate peels were 26916.66 mg GA eq./100 g dw, 17316.37 mg QE/100 g dw, 15847.74 mg/100 g dw, 14693.31 mg/100 g dw, 783.82 mg/100 g dw, 188.59 mmol Trol. eq./g dw, and 99.01 mmol Trol. eq./g dw respectively. Their average values in vitro bioaccessibilities were 43.13, 27.82, 62.61, 73.79, 16.96, 57.22 and 31.71%, respectively. It was determined that the initial total phenolic content, total flavonoid content, ellagic acid and antioxidant activity levels of the samples significantly decreased after digestion. Nevertheless, bioaccessibility of Punicalagin A and Punicalagin B significantly protected after digestion. α-amylase and α-glucosidase inhibitory activities of pomegranate peels range from 0.06 to 0.14 mg/L and 3.01 to 3.64 mg/L respectively. It was determined that all three varieties showed higher antidiabetic activity compared to acarbose. As a result, pomegranate peel ellagitannins after in vitro digestion had high bioaccessibility. Pomegranate peel with high antioxidant and antidiabetic activities is a natural source that can be used in the pharmacology, food and cosmetics industry.