Analysis of flavonoids content and antioxidant capacity in different Chinese jujube types

In order to select germplasm resources of Chinese jujube with high flavonoids content and strong antioxidant capacity, providing a reference for Chinese jujube fruits deep processing, 12 varieties fruits were used in this study, total flavonoids content was measured using NaNO₂-Al(NO₃)₃-NaOH method, and the total reducing power, DPPH and ABTS^+· free radical removing ability were used to evaluate the antioxidant capacity. The flavonoids content of different Chinese jujube types (cultivars) had obvious differences, ranged from 2.601 to 11.863 mg g^‑1 DW, flavonoids content of sour jujube was the highest (11.863 mg g^‑1 DW), followed by three varieties of intermediate type (7.383-10.446 mg g^‑1 DW). Fruits of eight cultivated Chinese jujube varieties had the lowest flavonoids content (2.601-5.830 mg g^‑1), while their flavonoids content had also significant differences. There was significantly positive correlation between total flavonoids content of 12 Chinese jujube varieties and total reducing power, DPPH and ABTS^+· free radical clearance rate, the correlation coefficients were 0.981**, 0.961**, 0.766**, respectively. Sour jujube had both the highest flavonoids content and the strongest antioxidant capacity, the intermediate type was the second, and cultivated varieties had the lowest.