Change in Chemical Components and Antioxidant Activity of Adzuki Beans during Germination

Abstract

In East Asian countries such as Korea, China, and Japan, adzuki beans are consumed as 'an' or 'ann' (adzuki paste) or boiled and sweetened whole beans, and used in desserts, snacks, and confectionery items (1). Germination is a processing method by which the quality of this cereal can be improved for both digestibility and physiological function (2). The purpose of this study was to evaluate the antioxidant compounds and antioxidant activities of the methanolic extracts from adzuki bean (Vigna angularis (Willd.) Ohwi & H. Ohashi) sprouts. To determine the antioxidant compounds in the methanolic extract, the content of total polyphenol, flavonoids, and anthocyanins were measured by spectrophotometric methods. These were evaluated for antioxidative activities by ABTS and DPPH radical scavenging activities. The adzuki bean sprouts extracted by separation with buds and grains. The methanolic extracts from adzuki beans sprouts showed generally higher antioxidant compounds and antioxidant activities than the extracts from ungerminated adzuki beans. The total polyphenol, flavonoids, and anthocyanins contents of the ungerminated adzuki beans were 5.90–27.45, 8.17–27.23 and 2.70–7.32mg/g, respectively. The total polyphenol contents on buds and grains of the germinated adzuki bean were 25.20–32.35 and 14.69–16.13mg/g sample, respectively. The ABTS and DPPH radical scavenging activities of the ungerminated adzuki beans were 0.70–1.09 and 0.34–0.85mg Trolox equivalent antioxidant capacity (TEAC) per g sample, respectively. The ABTS and DPPH radical scavenging activities on buds and grains of the germinated adzuki bean were 45.43–55.96 and 31.74–40.30, and 6.07–8.81 and 5.21–9.39mg TEAC per g sample, respectively.