Soybean is one of the most common food materials for making traditional Korean foods such as soybean paste, soy source and soy snack, and their manufacturing processes include heat treatment of soybean. This study was carried out to investigate the effect of heat treatment on the physicochemical properties of soybean. All samples were heat treated under commercial steamed, puffed or air-fried conditions, and then the protein molecular weight distribution, thermal properties, fluorescence intensity, protein solubility, and water and oil holding ability of the heat treated soybeans were examined. Sodium dodecyl sulfate polyacrylamide gel electrophoresis indicated that heat treatment caused fragmentation of polypeptide chain in soybean, showing the band of low molecular ranging from 17 to 40 kDa. The differential scanning calorimetric analysis showed the decrease of enthalpy values (ΔH) by heat treatment. Fluorescence spectroscopy indicated that the heat treatment caused lipid oxidation as proved by increasing emission intensity. The protein solubility at pH 3-6, and water holding capacity of heat treated soybeans were the higher than no treatment. These results suggest that the heat treatment resulted in decreased enthalpy values, and increased protein degradation, lipid oxidation and water affinity of soybean. Moreover, the effect of heat treatment on physiochemical properties of soybeans was more significant under air-fried condition.

• 김순희(농촌진흥청 국립농업과학원 농식품자원부 발효식품과) | Sun Hee Kim (Fermented Food Science Division, Department of Agro-food Resources, Nat’l institute of Agricultural Sciences, Rural Development Administration, Wangju 55365, Korea)
• 정은숙(농촌진흥청 국립농업과학원 농식품자원부 발효식품과) | Eun Suk Jung (Fermented Food Science Division, Department of Agro-food Resources, Nat’l institute of Agricultural Sciences, Rural Development Administration, Wangju 55365, Korea)
• 김소영(농촌진흥청 국립농업과학원 농식품자원부 발효식품과) | So Young Kim (Fermented Food Science Division, Department of Agro-food Resources, Nat’l institute of Agricultural Sciences, Rural Development Administration, Wangju 55365, Korea)
• 박신영(농촌진흥청 국립농업과학원 농식품자원부 발효식품과) | Shin Young Park (Fermented Food Science Division, Department of Agro-food Resources, Nat’l institute of Agricultural Sciences, Rural Development Administration, Wangju 55365, Korea)
• 조용식(농촌진흥청 국립농업과학원 농식품자원부 발효식품과) | Yong Sik Cho (Fermented Food Science Division, Department of Agro-food Resources, Nat’l institute of Agricultural Sciences, Rural Development Administration, Wangju 55365, Korea) Corresponding author