The effect of high hydrostatic pressure on the structure of soybean flake and the characteristic of cold-pressed soybean oil

Abstract

High hydrostatic pressure (HHP) is expected to solve the problem of low yield of cold pressed soybean oil (CPSO). In this study, HHP was applied to soybean flakes to investigate its mechanism of action in terms of protein structure, moisture distribution, and the microstructure of the soybean flakes. Additionally, the physicochemical properties and antioxidation capacity of CPSO were examined under varying HHP pressures and durations. The results indicated that HHP caused denaturation and aggregation of soybean proteins, while also disrupting the oil bodies and cell walls of soybean cells, leading to the aggregation of oil into oil droplets. Furthermore, HHP induced the conversion of free water and weakly bound water to tightly bound water in the soybean flakes, which enhanced the plasticity and elasticity of the material. The yield of CPSO was significantly (p < 0.05) increased by approximately 10%, reaching 80.27% at 300 MPa for 6 min. HHP also increased the content of unsaturated fatty acids, mainly oleic, linoleic and linolenic acids, while decreasing the content of stearic acid in CPSO, compare to the control group. Additionally, HHP enhance the antioxidant activity of CPSO and inhibited the activity of lipid oxidase (LOX), thereby delaying the oxidation of CPSO.