Characterization of particles in soymilks prepared by blanching soybeans and traditional method: A comparative study focusing on lipid-protein interaction

Abstract

The beany flavor of soymilk can be eliminated by blanching soybeans at high temperatures. However, compared with the traditional preparation methods, this pre-extraction heating process may have additional effects on protein aggregation. In this study, the distribution of lipid and protein was analyzed by an ultracentrifugation method that separates different fractions of soymilk on the basis of the size and density of particles. For traditional soymilk, results showed that ∼95% of total lipids were enriched in the floating fraction. For the soymilk prepared by blanching soybeans (blanched soymilk), only ∼ 55% of total lipids were found in the floating fraction, in accordance with ∼40% of total lipids presenting in the particulate fraction. SDS-PAGE also showed that the oleosin band existed in the particulate fraction of the blanched soymilk. Moreover, compared with traditional soymilk, blanched soymilk exhibited an obvious red shift in the intrinsic fluorescence spectrum and was composed of particles with significantly high surface hydrophobicity. In conclusion, blanching process alters the denaturation and aggregation mechanism of soymilk particles, thus trapping parts of oil bodies into particulate proteins.