Impact of Iron (II) Chloride Treatment on the Physical and Metabolic Changes in Mungbean Sprouts.

Legume crops are rich in carbohydrates, proteins, and various secondary metabolites such as isoflavones. Micronutrient treatments regulate plant biological activities, including stomatal function, hormone balance, and antioxidant accumulation, thereby improving resistance to environmental stress. This study investigated the effect of FeCl2 treatment, which changed the seed coat color, on the physical and biochemical characteristics of mungbean sprouts. After 72 h of cultivation with FeCl2 (Fe-72 h), no significant differences in physical traits were observed compared with the control. However, the levels of isoflavone aglycones (daidzein, genistein, and glycitein) were significantly higher. These findings suggest that FeCl2 treatment does not affect the physical quality of mungbean sprouts but enhances their metabolic quality by catalyzing isoflavone biosynthesis, as these compounds function as iron chelators. Tissue-specific analysis revealed that the seed coat and cotyledons accumulated the highest levels of isoflavone aglycones. The seed coat and cotyledons are directly exposed to FeCl2 during soaking, whereas newly developing tissues, such as the hypocotyl, are only indirectly affected. This difference in mineral exposure among tissues likely influences the biosynthesis of secondary metabolites. The observed increase in isoflavone content may improve stress resistance during mungbean cultivation and enhance the nutritional quality of mungbean sprouts as a health-promoting food.