Main Nutritional and Functional Ingredients and Antioxidant Evaluation of Xanthoceras sorbifolia Bunge Bud Tea and Leaf Tea

With the Xanthoceras sorbifolia Bunge bud tea and leaf tea grown on Gaotai, Zhangye as the test materials, the nutritional functional components and antioxidant activity of them were compared. INQ method was used to evaluate the quality of its nutritional ingredients and the correlation between functional ingredients and antioxidant capacity was analyzed. The results showed that the contents of K, Zn, Cu and K/Na in bud tea were significantly higher than those in leaf tea (P<0.05), and both had the characteristics of high K and low Na. The crude protein content of bud tea was significantly higher than that of leaf tea (P<0.05), while the crude fat content was the opposite. Nutritional quality evaluation revealed that the INQ of bud tea, leaf tea K, Ca, Fe, Mn, Zn, Cu, crude fat, and crude protein were all >1. Na, Mg and total soluble sugar INQ of bud tea<leaf tea<1. The content of polyphenols in bud tea was significantly higher than that in leaf tea (P<0.05), and there was no significant difference in the content of flavonoids. The IC₅₀ of bud tea and leaf tea on DPPH free radical, ABTS free radical and O₂⁻· scavenging capacity were 2.52 and 2.69, 1.65 and 1.74, 1.64 and 2.10 μg·mL⁻¹, respectively, the positive control rutin had no IC₅₀ within the concentration range, and the antioxidant capacity was bud tea>leaf tea>rutin. Correlation analysis showed that the contents of polyphenols and flavonoids in bud tea and leaf tea were positively correlated with DPPH free radical, ABTS free radical and O₂⁻· scavenging rate (P<0.01), the correlation coefficients of bud tea and leaf tea ranged from 0.892 to 0.990 and 0.879 to 0.994. In conclusion, the nutritional value and antioxidant capacity of Xanthoceras sorbifolia Bunge bud tea are better than leaf tea, and it has the potential to develop new products.