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The properties and applications of soybean protein isolates (SPIs) have been extensively investigated. In this study, we determined the optimal conditions for the preparation of the DND358 soybean protein isolate (DND358-SPI), assessed its physicochemical and functional properties, and investigated its potential applications in the food industry. According to the results, the highest extraction rate of DND358-SPI was observed when the pH was 9.5, the temperature was 55 °C, the duration was 80 min, and the material-to-liquid ratio was 1:20 (w/v). With regard to the functional properties, the water-holding capacity (WHC) and oil-binding capacity (OBC) of DND358-SPI were higher than those of other varieties, reaching 4.73% and 11.04%, respectively. In addition, the hardness, adhesiveness, chewiness, and resilience of DND358-SPI were higher than those of other varieties, reaching 159.27 g, 186.07 g, 6.78 mj, and 1.88, respectively. These findings indicate that DND358-SPI can reduce cholesterol levels and may be used to produce cholesterol-lowering food products.

The objective of this study was to determine if genotypes with differing globulin subunit compositions affect the hypocholesterolemic effect (HCE) of soy protein isolates (SPIs). Six SPIs (300 mg/kg/day), which differed in the 11S/7S globulin subunit composition, and fenofibrate (FF) (30 mg/kg/day), a hypocholesterolemic drug, were administered by gavage for 28 days to hypercholesterolemic model rats (HMRs). Blood samples were collected to measure serum lipid parameters. Hepatic histopathologic and lipid biochemical data were collected, and the expression of cholesterol metabolism-related key genes was analyzed. Our results demonstrated that soybeans differing in genotype generate SPIs with marked different HCEs, and the mechanism underlying the various HCEs of SPIs is associated with differential expression of hepatic cholesterol metabolism-related key genes in HMRs. 7S(α′+α)-Null genotype provided a greater effect on increasing HDL-C level, and daily ingestion of SPI-2 (null α′, α) might significantly contribute to increase HDL-C level in HMRs.