The Effect of Tapioca Starch Addition on the Growth of Rhizopus sp. in Red Bean (Phaseolus vulgaris L.) Fermentation for Tempeh Production

Tempeh is commonly produced through soybean fermentation, but red beans (Phaseolus vulgaris L.) have potential as an alternative raw material. Fermentation depends on nutrient availability, particularly carbon sources that support mold growth. Adding tapioca starch may provide an additional carbohydrate source and influence tempeh quality. This study aimed to evaluate the effects of tapioca starch addition on the mycelial growth of Rhizopus sp., its microscopic characteristics, and the organoleptic properties of red bean tempeh. Four treatments were applied: T0 (0%, control), T1 (5%), T2 (10%), and T3 (15%), using 100 g of red beans per experimental unit. Mycelial growth was assessed after 24 and 48 hours of incubation, and microscopic characteristics were examined using a microscope. Organoleptic evaluation covered color, aroma, texture, and taste. Mycelial growth data were analyzed using one-way analysis of variance (ANOVA), followed by Duncan’s Multiple Range Test (DMRT) when significant differences were detected. Tapioca starch addition significantly affected mycelial growth. At 24 hours, T2 and T3 showed the highest growth scores, whereas at 48 hours, T3 exhibited the highest score and differed significantly from the other treatments. Microscopic examination revealed branched aseptate hyphae, erect sporangiophores, round-to-oval sporangia, and columellae. No apparent morphological differences were observed among treatments, although denser mold growth was observed in T3. In the organoleptic evaluation, T3 received the highest average score (3.70), while T1 received the lowest (3.29). Overall, the 15% tapioca starch treatment produced the highest mycelial growth score at 48 hours and the highest average organoleptic score, without apparent changes in the microscopic morphology of Rhizopus sp.