Analysis of bioactive aglycone isoflavones in soybean and soybean products

Purpose The purpose of this paper is to investigate isoflavone aglycone concentrations in commercial soybean and soybean products in Taiwan. Design/methodology/approach Isoflavone concentration was determined by high performance liquid chromatography method. The samples included soybeans, non‐fermented (tofu, soymilk, soybean meal) and fermented (natto, miso and sufu) soybean products. Findings The total isoflavone concentration in soybean and soybean products was approximately 109‐508 mg/100 g. Isoflavone aglycones had the concentration of 2‐19 per cent of total isoflavones in soybeans and non‐fermented soybean products. There was a broad diversity of isoflavone aglycones at 4‐94 per cent of total isoflavones in fermented soybeans. Originality/value The study provides new information about distribution of bioactive isoflavone aglycones in soybean and soybean products. Isoflavone glucosides were the major components in all soybean and non‐fermented products, while isoflavone aglycones were abundant in sufu and partially in miso of soybean fermented products. The information should be used to establish that positive consumption of bioactive aglycones isoflavones may be more efficient for improving the physiological functions for human health.