Utami, Rahayu

Abstract

Tempe is a fermented soybean food in Indonesia. Tempe was commonly produced about 24-48 hours fermentation. Tempe is referred as over-fermented tempe after the 48 hours fermentation has been completed. The over-fermented tempe known as tempe semangit and tempe bosok. Tempe semangit is over-fermented tempe (slightly overriped) which is obtained by lengthening the fermentation 48-72 hours longer than fresh tempe fermentation, whereas tempe bosok (overripe tempe) needs more than 72 hours of over-fermentation. Therefore, over-fermented tempe has a brown color, pungent odor, and soft textures compared to the white compact cake of fresh tempe. Over-fermented tempe is popular in Javanese culture as an umami seasoning in traditional foods. Over-fermented tempe have been prepared by several different periods including : 0, 24, 48, 72 and 96 hours after the tempe production. Over-fermented tempe was extracted to obtain water soluble extracts (WSEs). The water soluble extracts (WSEs) were analyzed for crude proteins, total acids, total sugars, pH value, total amino acids, free amino acids, HPLC profile, taste activity value and umami taste dilution factors. Analysis of variance (ANOVA) was performed on crude protein, total acids, total sugars and pH value. As shown by ANOVA, crude protein and pH value were not statistically different between the fermentation periods, but were statistically different on total acids and total sugars. Free amino acids were characterized for their tasting and taste activity values. Based on the taste activity value, the taste of WSEs was umami and bitter. WSE from sample with 72 hours over-fermentation had umami taste activity value higher than bitter taste activity. The ratios of umami and sweet taste activity value to bitter taste activity were found between 1.2-1.6 in the mentioned WSE. There was a positive correlation between the taste rasio and umami taste dilution factor (r = 0.843 dan p = 0.002). The umami taste dilution factor was the result of sensory analysis of 5 times concentrated WSE. The highest ratio 1.6 belongs to WSE with 72 hours over-fermentation which had the highest dilution factor 256. Umami taste intensity WSE with 72 hours fermentation was determined with the existence of umami and bitter tasting free amino acids. In general HPLC profile indicated the composition in WSE’s fractions. Fraction 2 of each WSE of over-fermented tempe dominantly consisted of hydrophilic components, in contrast Fraction 3 of each WSE of over-fermented tempe was dominated by hydrophobic components. Fraction dominantly consisted of hydrophilic components having a higher intensity of umami taste.