Changes in biochemical and nutritional properties of bekang-um (fermented soybean) prepared by traditional method and customized incubator

Abstract

Effect of controlled and uncontrolled fermentation temperature on the microbial load, biochemical changes and change in nutritive value of bekang-um was studied in an attempt to upgrade the traditional fermentation technology of soybean, Glycine max (L.) Merr. The sterile cooked beans were fermented using a low-cost wooden incubator developed previously, adjusted at a constant temperature (35°C) and also under direct sunlight for 4 days following the traditional method. The microbial load, biochemical changes and changes in nutritive values of both the beans fermented were compared under controlled and uncontrolled temperature. The result showed that the viable cell counts, pH, free amino acids, proteolytic activity and alpha amylase activity increased in both the fermenting conditions throughout the process while the reducing sugar increased in the first day and decreased gradually with fermentation in both conditions. There is also an increase in moisture, protein and calorific value, and a decrease in carbohydrate, fats and ash value in both conditions. Fermentation under controlled temperature gave the higher levels of alpha amylase and proteolytic activities, viable cell counts, pH, free amino acids and nutritive value. These results suggested that fermentation proceeds at higher rate under controlled temperature using low-cost incubator could be utilized for the commercial production of bekang-um as the fermentation time could be reduced from three days to two days in addition to its simpler technology.