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Background : The major components in Astragalus membranaceus are isoflavonoids, triterpene and polysaccharides. Also, isoflavonoids was composed to aglycon and glucoside derivatives. In this study, we performed fermentation process (enzyme treatment) and steam processing (high temperature and pressure) to increase aglycon such as formononetin and calycosin.
Methods and Results : The steam processing was performed at a lot of conditions, such as temperature (80, 100, 120℃) and time (30, 60 and 120 min). Fermentation processing carried out by A. membranaceus extract fermented with microorganisms which have high β -glucosidase activity (selection by esculin agar method) for detached glucose from isoflavonoids, converted to algycon. The isoflavonoids were analyzed using high pressure liquid chromatography (HPLC) in fermentation product of A. membranaceu extract by treated with steam processing at various conditions. As a result of β-glucosidase activity by pNP assay, we selected three strains, Pediococcus pentosaceus, Weissella cibaria and Saccharomyces cerevisiae. Isoflavone aglycon was the highest in fermentation product by S. cerevisiae for 3 days, but change of isoflavonoids was not observed in steam processing. The calycosin-glucoside and ononin were reduced in fermentation product of A. membranaceus extract, whereas calycosin and formononetin was increased.
Conclusion : This results showed that isoflavone glycoside converted to isoflavone aglycon in A. membranaceus by fermentation process, it seems to be available for industrial use.
