No abstract

Bacteria grew to viable populations of 10(8)-10(9) cfu/g during the fermentation of soybeans into tempe with the fungus, Rhizopus oligosporus. Bacillus pumilus and B. brevis were the predominant bacterial species, reaching populations of approximately 10(8) cfu/g during the 48 h fermentation. Species of Streptococcus faecium, Lactobacillus casei, Klebsiella pneumoniae and Enterobacter cloacae also contributed to the fermentation and achieved populations of 10(6)-10(7) cfu/g.

Soybeans were soaked for 24h in tap water at 30°C in preparation for tempe fermentation. Soaking was conducted under conditions that give a microbial fermentation, and in the presence of antibiotics where microbial growth was inhibited. Sucrose, stachyose and raffinose were the main di-and oligosaccharides in the beans, and their concentrations decreased by 84, 65 and SO%, respectively, during soaking. Glucose, fructose and galactose were found in the soak-water along with lesser amounts of sucrose, melibiose, raffinose and stachyose. Glucose was the main substrate for microbial growth in the soak-water. The concentrations of mono-, diand oligosaccharides in the beans and in the soak-water were determined by the activity of invertases and a-galactosidases endogenous to the beans, diffusion of the sugars into and out of the bean, and the species of micro-organism growing in the soak-water. KeywordsFermentation, soybean microbial metabolism, oligosaccharide breakdown.

Soybeans were soaked for 24 h in tap water at 30°C in preparation for tempe fermentation. Soaking was conducted under conditions that give a microbial fermentation, and in the presence of antibiotics where microbial growth was inhibited. Valeric, propionic, formic and acetic were the main acids in the beans. Their concentrations decreased progressively during soaking as they were leached from the bean into the soak-water. At the end of soaking, lactic and malic were the main acids in the beans. They were produced by microbial fermentation in the soak-water and diffused into the beans. The concentration of acids produced in the soak-water was determined by the microbial species responsible for the fermentation. KeywordsFermentation, soybean microbial metabolism, organic acid metabolism.