The Effect of Tofu Liquid Waste Acidity as a Soaking Agent for Soybeans in Expediting the Tempeh Fermentation Process

The tofu industry is a crucial food industry in Indonesia, providing highly nutritious food as an alternative to animal protein. In its production process, besides yielding tofu, it also generates liquid tofu waste. Despite its negative environmental impact, liquid tofu waste has a beneficial aspect—it serves as a soaking agent for soybeans, expediting the tempe fermentation process. Tempe, an authentic Indonesian food, undergoes a critical fermentation process, where any malfunction can significantly affect its quality. This study involved the creation of tempe, utilizing soybeans soaked in liquid tofu waste for 6, 9, and 12 hours, along with soybeans solely immersed in well water as a control. The subsequent steps included draining, peeling, steaming the soybeans for 15 minutes, pouring them into trays, letting them cool, sprinkling 3 grams of tempe yeast, packaging them in plastic with 100 grams of soybeans each, and then fermenting. The observation of tempe involved assessing the mold growth rate and the whitest color of tempe across various treatments. A comparison of the tempe preference test with soybeans soaked in liquid tofu waste, featuring different pH levels, was conducted through a physical examination. Twenty panelists were asked to compare tempe variants (A, B, C, and control) based on color, aroma, texture, and taste. The results are tabulated, and a taste test was performed by cutting each tempe into cubes, seasoning with salt, frying, and obtaining evaluations from 20 panelists. The research findings indicate that the optimal soaking time for soybeans in liquid tofu waste, to achieve the ideal pH for tempe fermentation, is 9 hours, resulting in a pH of 4.2. The optimal fermentation time for soybeans is 8 hours, coinciding with a pH of 4.2. Soybeans soaked in liquid tofu waste with varying pH levels produce tempe with nearly identical preference scores.