Abstract:

Pomegranate (Punica granatum L.) fruit is rich in anthocyanins, which has attracted great attention for its health benefits. The aim of this study was to optimize five parameters for the microwave-assisted extraction of anthocyanins from sweet pomegranate fruits from Lintong region, Shaanxi province and to evaluate the in vitro antioxidant activity of the extracted anthocyanins by DPPH radical scavenging, ferric reducing antioxidant power (FRAP), 2,2＇-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation (ABTS+) and ferrous ion chelating assays. The optimal extraction parameters of anthocyanins were as follows: pH value 1; solid/liquid ratio 1:13; length of extraction time 210 s; microwave power 360 W; and ethanol concentration 70%. An anthocyanin yield of 184.81μg/g was achieved under these conditions. Microwave power had a significant effect on anthocyanin yield (P ＜ 0.05). The extracted anthocyanins had the ability to scavenge DPPH and ABTS+ radicals, ferric reducing antioxidant power and ferrous ion chelating capacity in a linear concentration-dependent manner, with corresponding correlation coefficients (R2) of 0.9928, 0.9925, 0.9913 and 0.9945, and the IC50 values were 2.44, 1.14, 4.08 mg/L and 101.05 mg/L, respectively.

Key words: microwave assistance, pomegranate, anthocyanin, antioxidant activity