PROTEIN HYDROLYSIS DURING SOYBEAN TEMPE FERMENTATION WITH RHIZOPUS-OLIGOSPORUS

Hydrolysis of soybean protein during fermentation in a rotating drum r eactor (RDR) was compared with hydrolysis during the traditional stati onary tempe fermentation process. An increase of water-soluble nitroge n was observed. After 72 h of fermentation, 18.5, 25.4, 27.1, and 34.0 % (w/w) of total N were found for the traditional stationary process a t 25, 30, and 37 degrees C and for the RDR at 36 degrees C, respective ly, compared to 2.0% in cooked soybeans at the start of the fermentati on. The fungal activity in the RDR continued longer than in the tradit ional process. This was achieved by avoiding heat and mass transfer li mitations. In the RDR a higher degree of hydrolysis, as well as higher levels of water-soluble and TCA-soluble nitrogen, were found after 72 h of fermentation compared with the stationary process at 37 degrees C. beta-Conglycinin was hydrolyzed more rapidly than glycinin, which i s probably related to the chemical structure; beta-conglycinin is more sensitive toward protease activity.