Changes in the Composition and Size Distribution of Soymilk Protein Particles by Heating

Abstract

The protein particles in soymilk were fractionated in size by differential centrifugation. Particles of more than 100 nm in diameter (LSP) constituted 40% of the total protein in raw soymilk, 70% of the protein components being US globulin. LSP was not formed in the presence of 2-mercaptoethanol and sodium ascorbate. LSP was decreased by heating, and particles of 100-40 nm in diameter (MSP) were increased. The formation of MSP was not due to any degradation of LSP but to the combination of supernatant proteins of less than 40 nm in diameter with each other. MSP formed by heating contained the β subunit of 7S and the basic subunit of 1 IS as main components. The particles of more than 40 nm in diameter (LSP+MSP) constituted 50% of the total protein in both raw soymilk and soymilk.