CHEMICAL AND ENZYMATIC CHANGES DURING THE FERMENTATION OF BACTERIA-FREE SOYA BEAN TEMPE

Amounts of dry matter, ash, protein, free ammonia, crude lipid, glycer ide-glycerol, free fatty acids, free glycerol, glucosamine, protease a ctivity and lipase activity were monitored during the fermentation of bacteria-free tempe made with acidified soya bean cotyledons and Rhizo pus oligosporus NRRL 2710 at 30 degrees C. During the phase of mycelia l growth (0-32 h) the total dry matter decreased by approximately 10% (w/w), accounted for by losses of crude lipid (3% of initial dry matte r), protein/amino acids (0.5%), and unidentified compounds (6.5%). Dur ing the phase of mycelial senescence (60-180 h), decrease in dry matte r (12% of initial dry matter) was due almost entirely to loss of crude lipid. Lipase activity and the production of free fatty acids occurre d from the earliest stages of the fermentation. The production of only small amounts of free glycerol indicates that triglycerides were prim arily hydrolysed to partial glycerides and free fatty acids. Protease activity and production of free ammonia were also detected at the earl iest stages of the fermentation. During the phase of mycelial senescen ce, amounts of crude lipid and glycerol decreased in the absence of fu ngal growth, possibly due to the activity of enzymes released from sen escent mycelium.