Effect of grinding temperature on hydroperoxide and off-flavor contents during soymilk manufacturing process

Hydroperoxides and n-hexanal of soymilk made at different temperatures in the soybean grinding process were investigated. Both hydroperoxides and n-hexanal showed maximum amounts at 30 degreesC, 37.78 mumol/g, and 1.94 mg/g, respectively. However, at 3 degreesC and 80 degreesC, amounts of hydroperoxides were about half of that at 30 degreesC. N-hexanal showed high correlation with hydroperoxides except for at 80 degreesC. It suggests that controlling the grinding temperature is effective to reduce hydroperoxidation and off-flavor content. Protein solubility, an important index of soymilk, was decreased as the temperature increased. Grinding soybeans at low temperature is considered an economical method to produce soymilk having less off-flavor and high protein.