Abstract:

【Objective】 The anthocyanins profiles and antioxidant activity of seed coats from different black soybean varieties were investigated. 【Method】 Crude extract solution of black soybean seed coats anthocyanins of 60 varieties was obtained by soaking seed coats in acidified methanol. External standards were used to determine the composition and content of anthocyanins in each variety by HPLC gradient elution method. The oxygen radical scavenging capacities expressed as ORAC values of black soybean varieties were also evaluated. 【Result】 Six anthocyanins were found totally in 60 black soybean varieties including delphinidin-3-glucoside, cyanidin-3-galactoside, cyanidin-3-glucoside, petunidin-3-glucoside, peonidin-3-glucoside and malvidin-3- glucoside. All the 6 components were detected in 44 varieties of the black soybean, and only 4 or 5 anthocyanins were detectable in the other 16 varieties. Cyanidin-3-glucoside was the predominant anthocyanin in all the analyzed varieties. Total contents of anthocyanins and each component showed significant differences between varieties. Total anthocyanins content and ORAC in various black soybean varieties were highly different with the ranges of 98.8-2 132.5 mg/100g and 212.5-1 834.6 μmol TE/g, respectively. A significant correlation was found between anthocyanin concentration and ORAC values (r=0.62, P＜0.001). Sixty black soybean varieties were divided into three groups by K-means clustering analysis, which showed divers levels of nutritional or bioactive traits.【Conclusion】The components of anthocyanins in different black soybean varieties were similar, but things were different when it came to the content of individual anthocyanin. Anthocyanins are most significant antioxidant components in black soybean seed coats.

Key words: black soybean, seed coat anthocyanins, HPLC, ORAC