Effect of Heat Treatment on the Lipid Peroxide Content and Aokusami (Beany Flavor) of Soymilk

With the objective of minimizing aokusami (beany flavor), which is an undesirable aspect of soymilk flavor, we studied the effects of heating on lipid peroxide content, a factor contributing to the beany flavor. We also prepared various desserts containing soymilk using this heating process, and evaluated the effects of heating by sensory test. The lipid peroxide content of soymilk prepared from soaked and swollen soybeans steamed at 75°C in a relative humidity of 80-90% for 10 minutes was substantially lower than that in soymilk prepared from soybeans which lacked lipoxygenase and was 14% or less that of non-heat-treated soybeans. Additionally, the lipid peroxide content of soymilk prepared by blanching soaked and swollen soybeans in boiling water for 30 seconds was comparable to that found in soymilk prepared from lipoxygenase-lacking soybeans. The beany flavor of custard pudding, Bavarian cream, and Annin tofu prepared with soymilk obtained from heat-treated soybeans was significantly improved.