The change of phenolic compounds and radical scavenging activity of black soybean flours after germination and roasting treatment were evaluated as a part of the purpose of setting the quality of black soybean flours for each application. The moisture content of roasted black soybean flours decreased significantly according to roasting temperature and time, and the crude ash, protein, and fat contents increased. Water binding capacity of roasted black soybean flours without and with germination increased significantly according to roasting temperature and time, however water solubility index and swelling power decreased. The lightness of roasted black soybean flours was significantly decreased, and the redness and yellowness increased. The phenolic compounds and radical scavenging activity of roasted black soybean flours increase with increasing roasting temperature and time. The total polyphenol contents of roasted black soybean flours without and with germination were 5.43∼7.81 and 4.52∼6.17 mg GAE/g, and total flavonoid contents were 2.90∼3.50 and 2.34∼3.01 mg CE/g, respectively. DPPH radical scavenging activity of roasted black soybean flours without and with germination was 254.98∼415.05 and 171.95∼295.15 mg TE/100 g, and ABTS radical scavenging activity was 459.74∼596.37 and 422.95∼526.85 mg TE/100 g, respectively. As a result, it is necessary to set quality standards for each application considering the quality and antioxidant properties of roasted black soybean flours.

The change of quality characteristics and antioxidant properties of black soybean flours after germination and roasting treatment were evaluated. The moisture content of roasted black soybean flours decreased significantly according to roasting temperatures and times, and the crude ash, protein, and fat contents increased. The water binding capacity of roasted black soybean flours with and without germination increased significantly according to roasting temperatures and times; however, water solubility index and swelling power decreased. The lightness of roasted black soybean flours was significantly decreased, and the redness and yellowness increased. The phenolic compounds and radical scavenging activity of roasted black soybean flours increased with increasing roasting temperatures and times. The total polyphenol contents of roasted black soybean flours with and without germination were 5.43-7.81 and 4.52-6.17 mg GAE/g, and total flavonoid contents were 2.90-3.50 and 2.34-3.01 mg CE/g, respectively. The DPPH radical scavenging activity of roasted black soybean flours, with and without germination, was 254.98-415.05 and 171.95-295.15 mg TE/100 g, and the ABTS radical scavenging activity was 459.74-596.37 and 422.95-526.85 mg TE/100 g, respectively. As a result, it is necessary to establish quality standards for each application by considering the quality characteristics and antioxidant properties of roasted black soybean flours.

Quality characteristics of commercially available soybean and mung-bean flours in Korea were evaluated relative to product information such as bean content, price, chromaticity, proximate composition, water binding capacity, swelling power and solubility. Origin of raw materials was 23 in domestic products and 19 in imported products. The price of the product was 3.48 times more for raw soybean flour, 3.34 times more for fried soybean flour, and 3.47 times more for mung bean flour compared to imported soybean. In the domestic products, the lightness of raw soybean flour was higher than roasted soybean flour. The redness and yellowness of roasted soybean flour were higher than raw soybean flour. Moisture content of raw soybean flour was higher than roasted soybean flour, and crude fat, crude protein and carbohydrate content were higher in imported soybean flour. Ash and crude protein contents of mung bean were slightly higher than imported products. Water binding capacity of roasted soybean flour in domestic products was higher than raw soy flour, and there was no significant difference in solubility and swelling power. Correlation between quality characteristics of commercially available soybean and mung-bean flours products was found to be highly significant among measured items, except for solubility.