Author : Warawut Krusong

Summary : A study was conducted to produce tempeh with high vitamin B12 incorporating selected strains of Propionibacterium shermanii. Soybeans of the Phraputthabath variety were soaked in acidified distilled water (1 percent of 80 percent lactic acid) for 2 hours at 70 degree centigrade, dehulled by hand, and dried at 80 degree centigrade until the beans were superficially dry. The soybean cotyledons were sterilized and inoculated with Rhizopus oligosporus powdered inoculum at a rate of 0.25 g/50 g soybean and cell suspension of P. shermanii 1250 at 1 ml/50 g soybean. The mixture were incubated at 35 degree centigrade for 24 hours. Lactobacillus casei did not affect the Vitamin B12 production of P. shermanii 1250 in tempeh when added during the fermentation. Optimum conditions used for bench scale production were similar to those for the laboratory scale. Bench scale production of high vitamin B12-tempeh, performed in stainless steel trays (30 cm x 45 cm x 3 cm), yielded 297.47 ng vitamin B12/100g of mixture at optimum conditions of 2 cm thickness of sterilized soybena mass (1,400 g/tray) covered with non-perforated aluminum foil, and incubation period of 24 hr at 35 degree C. The chemical composition of high Vitamin B12-tempeh produced in trays at optimum conditions was also similar to that produced in laboratory scale. The mass balance in the production of high Vitamin b (subscript 12)-tmepeh in the tray at optimum conditions showed that 30.14 percent of total solids were lost during processing. Some intermediate metabolites involved in the pathway of vitamin B12 by P. shermanii 1250 in tempeh (as detected by gas chromatography) included acetic acid which increased and propionic acid which decreased as fermentation time progressed. Moreover, succinic acid and glycine decreased during fermentation. This research was the first to elucidate that mixed fermentation with R. oligosporus and P. shermanii 1250 enhanced high vitamin B12 production in tempeh.