Selenium Biofortification Enhances Functional Bioactive Components and Nutritional Quality of Edible Mung Bean Sprouts During Germination

This work aimed to identify the optimal edible germination period for mung bean sprouts and investigate how selenium biofortification modulates γ-aminobutyric acid (GABA), phenolic compounds, α-ketoglutarate (AKG), carotenoids, and vitamin C (VC), with a focus on improving their nutritional and functional quality as fresh edible vegetables. The results demonstrated that germination promoted the accumulation of GABA, total phenolics, total flavonoids, AKG, total carotenoids, and VC in sprouts. Nevertheless, excessively prolonged germination significantly decreased GABA, AKG, and VC contents (p < 0.05). Meanwhile, excessive lateral root outgrowth and full elongation of sprouts deteriorated both their functional bioactive profile and sensory edible quality. Accordingly, the 3-day germination stage was selected as the optimal harvest point for edible mung bean sprouts. Treatment with an appropriate concentration of Na2SeO3 further enhanced the contents of GABA, AKG, VC, and total carotenoids. In addition, selenium treatment significantly increased (p < 0.05) free total phenolic content (TPC) and total flavonoid content (TFC) while markedly reducing (p < 0.05) bound TPC and TFC across all tested germination stages. UPLC-ESI-MS/MS analysis revealed vitexin and isovitexin as the predominant phenolic compounds in germinated mung beans, detected in both free and bound polyphenol fractions. During germination, free vitexin and isovitexin declined, whereas bound forms of these two compounds increased. Compared with untreated controls, Na2SeO3 biofortification elevated free vitexin and isovitexin and lowered their bound fractions at different germination times. Collectively, these findings provide valuable theoretical foundations to guide the production of selenium-biofortified mung bean sprout products enriched with health-promoting bioactive ingredients for functional food applications.