The physicochemical properties of soy sauce made from tempeh

Abstract

Tempeh is a fermented product that uses Rhizopus sp. to bind raw material into a sliceable cake. Soy sauce is a fermented food product with umami and salty flavor made by Aspergillus sp. for koji fermentation and then soaked in salted water. Tempeh has a shelf life of three days, but soy sauce has a shelf life of six months at room temperature. Therefore, we can increase the shelf life of unconsumed tempeh by turning it into soy sauce. This study compared the physicochemical properties of soy sauce made from tempeh. This study has two variables: length of tempeh fermentation times (three days and four days) and salt solution concentration (15%, 20%, 25%). We also use soy sauce made from soybean with Aspergillus sp. as a positive control. After the soy sauce was fermented for one month, pH, total dissolved solids, °Brix value, yield, color, acceptance test and just-about-right test were analyzed. Results from the acceptance analysis showed that soy sauce made from 3-days tempeh with 20% of salt has significantly higher acceptance compared to other sample with value of 5.37±1.73 (range 1-9) with represent neutral. This soy sauce has pH of 6.73±0.06, total dissolved solids of 9.73 ± 0.02% with 11.7 ± 0.02°Brix. For color analysis, soy sauce made from 3-days tempeh with 20% of salt showed higher lightness than soy sauce made from koji with 20% of salt. Meanwhile for just-about-right test, very salty taste attribute needs to be reformulated.