The effect of autoclaving on soluble protein composition and trypsin inhibitor activity of cracked soybeans

The effects of autoclaving conditions (heating for 5, 10 and 15 minutes at 0.5 bars over pressure) and oil-extracting temperatures (40°C, 60°C) on protein content, composition, and inhibitor activity of cracked soybeans were investigated. The results obtained indicated that oil-extracting method and heat treatment had significant influence on soluble protein content and composition. Raw soybean samples defatted at lower temperature had better solubility (535.42±2.10 mg/g) than those obtained by the Soxhlet procedure (345.53±2.80). The same results were obtained for nitrogen solubility index. Autoclaving combined with two oil-extraction methods decreased protein solubility to 180.32±1.50 -245.41±1.41 mg/g, while the dominant component of heat treated flours was 11S fraction. High content of glycinin fraction (44.59-41.10%) implies the possible use of treated samples in food industry. Residual activity of treated samples was 43.40-84.26%. Kunitz inhibitor (KTI) was responsible for residual inhibitor activity.