TEMPE FERMENTATION - SOME ASPECTS OF FORMATION OF GAMMA-LINOLENIC ACID, PROTEASES AND VITAMINS

During a tempe fermentation the concentrations of linoleic, and alpha- linolenic acids (ALA) decreased while the concentration of oleic acid increased. During fatty acid synthesis Rhizopus sp. produced only gamm a-linolenic acid (GLA) instead of ALA. The amount of GLA in tempe were influenced by varying external parameters. The proteolytic capacity o f 36 strains of the genus Rhizopus isolated from Indonesian tempe or t empe inocula was examined. There was a distinct increase in the amount of free amino acids during tempe fermentation. Fermentations with mix ed populations of bacteria and Rhizopus yielded a lower level of free amino acids, but an increase in total amount of amino acids. In compar ison to intracellular, and extracellular proteases the proteases of th e cell wall fraction are most responsible for proteolytic capacity of the different Rhizopus strains. Two isolated strains of Citrobacter fr eundii were found to be the best vitamin B-12 producers during the soa king of soybeans. In the solid substrate fermentation the Rhizopus mol ds formed vitamin B-6, riboflavin, and nicotinic acid. The addition of bacteria to the solid substrate fermentation resulted in a strong inc rease of active vitamin B-12 in tempe. In the presence of the Rhizopus mold, the vitamin B-12 formation by C. freundii was three times highe r than that of a fermentation without the mold.