Biotransformation and health potential of isoflavones by microorganisms in Indonesian traditional fermented soy products: A review

Soy products are a primary source of isoflavones, but many naturally occurring isoflavones are glycosides with low bioavailability. β-Glucosidase hydrolyzes the β-D-glucoside bond, releasing the aglycone form of isoflavones, which are more efficiently absorbed and offer enhanced health benefits, such as anti-inflammatory and anticancer effects. Microorganisms play a critical role in this biotransformation during fermentation by producing β-glucosidase. This review summarizes the microorganisms involved in converting isoflavone glycosides into aglycones during the fermentation of Indonesian traditional foods. The process, influenced by heritage-rich methods, determines the efficiency of aglycone production. Various unexplored microorganisms in Indonesian soybean-based fermented foods, such as tempeh, oncom, kecap, and tauco, produce β-glucosidase. These findings highlight the importance of optimizing traditional fermentation methods to maximize the health benefits of soy products.