To expand the usability of sprout soybeans, beans were treated with steaming (SS), germinating (GS), or roasting (RS), and then fermented with Irpex lacteus mycelia. Levels of free amino acids, β-glucan, and volatile components of treated sprout soybeans fermented with I. lacteus mycelia for 5 days were investigated. Free amino acid levels of SS-, GS-, and RS-treated beans fermented with I. lacteus were 5.38±0.29, 5.68±0.76, and 4.16±0.22 mg/g, respectively, at day 0, increasing to 19.42±2.32, 18.91±0.79, and 23.57±1.58 mg/g, respectively, after 5 days. The β-glucan content of SS-, GS-, and RS-treated beans fermented with I. lacteus were 0.64±0.15%, 0.46±0.88%, and 0.43±0.18% at day 0, respectively, and increased to 3.16±0.65%, 3.11±0.22%, and 3.20±0.88%, respectively, after 5 days. The treatment method did not significantly alter the β-glucan content of the soybeans, but, for all treatments, the β-glucan content did increase by more than four-fold following fermentation with I. lacteus (P<0.05). The level of the beany flavor components, such as 2-ethyl furan, n-hexanal, and 1-hexanal of sprout soybeans fermented with I. lacteus mycelia decreased after 5 days of fermentation. The results show that fermentation of soybeans with I. lacteus increases the levels of free amino acids and β-glucan while decreasing the level of undesirable odor components, thus, potentially increasing the utilization of sprout soybeans.

Keywords: sprout soybean, germinating, roasting, Irpex lacteus, β-glucan