Effects of Pre-heating on Freeze-thaw Fractionation of Soymilk

抄録

Raw soymilk separates into two layers (upper and lower) upon freeze-thawing. In this study, we investigated the effects of heating (50 – 95°C) before freezing on the freeze-thaw fractionation of soymilk. Proportion of the upper layer decreased as the heating temperature before freezing was elevated, and heating at 80°C completely inhibited the fractionation. The amount of protein in the upper layer decreased with higher heating temperatures, and the 7S globulin contents in the lower layer increased simultaneously. The particle size of the upper layer decreased with increased heating temperatures, whereas the particle size of the lower layer increased at temperatures greater than about 70°C. These results suggested that the changes in soymilk fractionation are likely due to the liberation of 7S globulin from lipid/protein complexes upon heating, and interactions among the proteins and lipid/protein complexes caused by freeze-mediated concentration.