Changes in Phenolics and Antioxidant Capability of Two Chinese Milk Vetch Sprouts During Germination

Chinese milk vetch (CMV) has high nutritional value, but it is often used as green manure and forage grasses, with low economic returns. This study aimed to broaden the channel of its resource utilization. Two CMV seeds from Hunan (Xiang No.1) and Anhui (Wan No.1) province were hydroponically developed to CMV sprouts. Taking mature stems and leaves of CMV as the positive control, the differences in phenolic composition and dynamic changes of antioxidant capability during 8~14 d after germination were analyzed and compared between two sprouts, as well as the correlation between phenolic substances and antioxidant activity. The results showed that the contents of total phenols (TPC), total flavonoids (TFC) and antioxidant capacity of two CMV sprouts had an upward trend during 8~14 d of growth. Wan No.1 sprouts performed better than Xiang No.1 sprouts. The 14^th-day Wan No.1 sprouts showed high TPC (7.31 mg/g dw), TFC (5.86 mg/g dw) and strong antioxidant activities. A total of 12 phenolic compounds were detected, including five more phenolic substances than mature stems and leaves, which were gallic acid, ferulic acid, vanillic acid, salicylic acid and syringic acid. Its dominant components were kaempferol (12.86±0.34 mg/g), apigenin (6.38±0.17 mg/g), quercetin (5.36±0.04 mg/g), p-coumaric acid (4.59±0.13 mg/g), gallic acid (3.01±0.11 mg/g), luteolin (3.00±0.02 mg/g) and ferulic acid (2.35±0.29 mg/g). Among them, the content of gallic acid was 13 times that of the 14^th-day Xiang No.1 sprouts, and the content of p-coumaric acid was 33 times that of mature stems and leaves. This study could provide preliminary theoretical support and related parameters for CMV seed selection and sprouts breeding, and it is recommended that CMV sprouts should be further focused and studied.