Abstract
Tofu wastewater can be utilized as a substrate for microorganisms that produce single-cell proteins (SCPs). Because different microorganisms have different cellular components, the composition of SCPs varies. Electro-stimulation has the potential to speed up fermentation and increase product yield. The goal of this study was to find the best way to produce SCPs from Aspergillus awamori, Rhizopus oryzae, and Saccharomyces cerevisiae in the tofu wastewater substrate using electro-stimulation. The experimental method was used in the study, the data were analyzed using independent t-test statistical analysis, and the best treatment was identified using the effective index method. This treatment consisted of producing SCP with electro-stimulation of -1.5 V and without electro-stimulation for 72 h for the yeast and 96 h for the mold at 25 °C in tofu wastewater that had already been conditioned to a pH of 5. The parameters measured included measurement of population of microorganism, change in pH, dry biomass weight, carbohydrate content, and protein content. Electro-stimulation reduced the optimum fermentation time of A. awamori SCP from 56 to 32 h, resulting in 0.0406 g/50 mL of dry biomass, 30.09% carbohydrate content, and 6.86% protein content. Meanwhile, the optimal fermentation time on R. oryzae and S. cerevisiae were not accelerated by electro-stimulation. The best treatment was A. awamori without electro-stimulation, which produced 0.0931 g/50 mL of dry biomass, 20.29% carbohydrate, and 7.55% protein.