Germination time and in vitro gastrointestinal digestion impact on the isoflavone bioaccessibility and antioxidant capacities of soybean sprouts

Abstract

Soybeans' isoflavone content increases with germination; nevertheless, their bioaccessibility in the gastrointestinal system is limited. This study evaluated the influence of germination time (1, 3, 5, and 7 days) and in vitro gastrointestinal conditions on the isoflavone profile of soybean sprouts. The total isoflavones (4.07 mg/g) and the malonyl genistin (1.37 mg/g) had the highest contents on day 5 in the gastric phase. The highest isoflavone bioaccessibility was observed in daidzein, genistein, and glycitin. An increase in antioxidant capacity was found during germination (day 7 > day 5 > day 3); however, the same trend was not observed during in vitro digestion. In summary, the results indicate that soybean sprouts germinated for 5 days may be more beneficial for consumption since they have the highest and most readily absorbed levels of isoflavones. These data suggest that soybean sprouts may be a functional food that provides bioavailable antioxidants.