Effect of sodium chloride and potassium chloride concentration on physicochemical, volatile aroma, and sensory characteristics of tempeh-based soy sauce

Tempeh, a traditional Indonesian food rich in nutrients, has a limited shelf life which can negatively impact its quality. To extend its shelf life and enhance its functional value, tempeh can be processed into soy sauce. Typically, soy sauce contains high levels of sodium, which is a dietary concern. Therefore, this study aims to learn about the salt concentration factor on physicochemical and organoleptic characteristics of tempeh-based soy sauce. This study used one factor: NaCl concentration of 10.0%, 12.5%, 15.0%, 17.5%, and 20.0% with variations in KCl concentration while the total salt in brine solution was 20.0%. After a month of fermentation, pH, total dissolved solids, volatile aroma compounds, and hedonic tests were conducted. This study demonstrated that increasing sodium chloride (NaCl) concentrations in tempeh-based soy sauce results in a decrease in pH and an increase in total dissolved solids over a one-month fermentation period. There were 108 volatile aroma compounds detected in all of the soy sauce samples, but only 18 of the same volatile aroma compounds were identified, consisting of alcohols (6), ethers (2), acids (2), aldehydes (2), organosilicon compounds (3), sulfuric component (1), and other compounds (2). The sensory evaluation revealed no significant differences between samples, though the highest panellist acceptance for aroma and taste was at 15.0% NaCl concentration.