Effects of Seed Germination on Physicochemical and Bioactive Compounds Characteristics of Velvet Bean Tempe

Abstract

Indonesia, known as the largest tempe-producing country globally with approximately 160,000 producers, faces a challenge in meeting the demand for tempe due to insufficient local soybean supply. To address this issue, Indonesia has been compelled to import significant quantities of soybeans, reaching 1.68 million tons in 2020, which escalated by 47.78% to 2.49 million tons in 2021. This study aims to scientifically investigate the impact of velvet bean seed germination on the physicochemical characteristics and bioactive components of velvet bean tempe. The research methodology involved quantitative analysis to obtain reliable results. The preliminary analysis established that the optimal velvet bean tempe fermentation time was 48 hours. Following germination, the physical properties of velvet bean sprouts exhibited an increase in weight accompanied by a reduction in bulk density and absolute density. Furthermore, the germination treatment resulted in decreased brightness, saturation, whiteness, and pH values, while simultaneously increasing the hardness of the tempe. Chemical analysis demonstrated that germination of velvet bean seeds led to an elevation in moisture content and a decrease in carbohydrate content within the produced tempe. Additionally, bioactive component analysis revealed that the germination treatment contributed to a reduction in total phenol content from 52.46 to 36.30 mg AAE/100g, antioxidant capacity from 132.80 to 66.90 mg GAE/100g, and GABA content from 54.20 to 21.50 mg/100g in the tempe. These findings provide valuable scientific insights into alternative ingredient utilisation and production processes optimisation of velvet bean tempe.