Bioactive compounds and antioxidant activity of mung bean (Vigna radiata L.), soybean (Glycine max L.) and black bean (Phaseolus vulgaris L.) during the germination process

Bioactive compounds and antioxidant activity of germinated mung bean, soybean and black bean sprouts were investigated to find out the effect of germination and the optimum germination time. We found that vitamin C gradually increased from zero. Compared to seeds, water-soluble protein and total flavonoid content showed a trend of sustained growth while vitamin E, total phenolic content increased at first and then decreased, the maximal value of total bioactive compound content was reached on the fifth day. The analysis of relative contribution revealed that total phenolics and total flavonoids made the highest (44.87–90.31%) contribution to total antioxidant activity. In conclusion, the optimum germination time for sprouts was 3–5 days when total bioactive compound content and antioxidant activities both reached their peak values, which provide a sufficient theoretical basis for dietary processing and lay a solid foundation for continued research.