Abstract
Soybeans soaked in water were ground with a domestic mixer and with stone mills (small for cereals and large for soybeans), and the effects of these different grinding methods on the lipid peroxidation of go (a ground unheated soybean slurry) were examined. The mixer increased the sample temperature during grinding, while the stone mills kept it unchanged or reduced it. Mixer grinding increased the PV and TBA values of the extracted oil with decreasing amount of the ground soybeans (30,60 or 90 g). Grinding with the small stone mill led to approximately the same PV as that by mixer grinding (90 g), but to a lower TBA value. Grinding with the large stone mill gave the smallest values for both PV and TBA. An increase in the grinding temperature tended to promote lipid peroxidation by each grinding method. Apart from the effect of temperature, however, the lipid peroxidation of go was suppressed by the use of stone mills, particularly by the large one.
