Effect of Grinding Methods, Heating Methods, and
Variety on Hexanal in Soymilk. Table 1 shows that
significant differences existed in hexanal levels among different
grinding methods, heating methods, and the two varieties. Hot
grinding resulted in significantly (p < 0.05) lower hexanal as
compared with the other two grinding methods. Figure 1 shows that the lipoxygenase activity of raw soymilk after hot grinding
was much lower than that from other two grinding methods. In
fact, hot grinding inactivated approximately 99% of the
lipoxygenase activities as compared to that in the cold ground
soymilk. It is obvious that the decrease in hexanal by hot
grinding was mainly due to the inactivation of the oxidative
enzymes at 80 °C. Our study is the first to report the effect of
grinding at various temperatures on soy odor in raw soymilk.
All other reported studies had reported the odor composition
in the finished soymilk products.