Changes in Anthocyanin, Proanthocyanidin, γ-Aminobutyric Acid Contents and Antioxidant Capacity of Black Soybean (Glycine max (L.) Merr.) Cultivar “Kurodamaru” During the Manufacture of Roasted Beans

Abstract

Changes in total anthocyanin, total proanthocyanidin, and γ-aminobutyric acid (GABA) contents and antioxidant capacity were investigated during the manufacture of roasted beans made from black soybean cultivar “Kurodamaru.” The contents of anthocyanin and proanthocyanidin decreased remarkably in black soybean during the water immersion process ; however, roasted beans showed contents of 53 % and 83 % on a dry matter basis, respectively, compared to raw soybeans. The GABA content of soybeans increased 5.3-fold during the immersion process, and subsequently decreased upon storage for 16 hours in a constant temperature warehouse and roasting for 20 min at 168°C. The oxygen radical absorbance capacity of roasted beans was significantly higher than that of raw soybeans (P <0.05).