Effect of freezing on physicochemical properties and microstructure of soy protein gels

This study aimed to analyze the dynamic evolution of physicochemical properties and microstructure in soybean protein gels subjected to freezing conditions. SPI, 7S, and 11S were used in experiments. A 12g/100g protein gel was formulated after 1 and 5 days of freezing. Subsequent determination and analysis encompassed various indices, including texture, subunit composition, sulfhydryl group content, water distribution, and microstructure. The findings revealed a significant increase in the hardness of SPI, 7S, and 11S protein gels with prolonged freezing time. The 11S gel exhibited the most substantial increase, followed by SPI and 7S. And the decreases in the water-holding properties of the protein gels were 10.08%, 1.19%, and 49.34%, with the largest decrease in the water-holding properties of the 11S protein gels. Conversely, the water-holding capacity and total sulfhydryl content of SPI, 7S, and 11S protein gels decreased over time during freezing. Subunit distribution analysis indicated darker bands at the top of concentrated and separation gels. The freezing process induced the formation and growth of ice crystals, altering the spatial network structure of protein gels. Consequently, the proportion of free water in all three soybean protein gels increased, leading to enhanced mobility and a looser network structure. • Effect of freezing on the properties of soy protein (SPI, 7S, 11S) gels. • Establishing a link between soy protein gels properties and structure after freezing. • Elucidation of difference mechanism in soy protein gels properties during freezing.