EFFECT OF THE DRYING METHOD ON BROWNING OF FLESH, ANTIOXIDANT COMPOUNDS AND ANTIOXIDANT CAPACITY OF CHINESE JUJUBE (ZIZYPHUS JUJUBA MILL.) FRUIT

The present study investigated the differences in ascorbic acid (AA), total phenolics (TP), total flavonoids (TF), antioxidant capacity (AOC) and browning value (BV) of Chinese jujube (Zizyphus jujuba Mill.) after four drying methods. 2, 2- diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity, trolox equivalent antioxidant capacity (TEAC) and reducing power (RP) were used as markers for AOC. The results showed that drying treatments had different degree of effect on AA, TP, TF, AOC and browning of jujube. Freeze-drying and vacuum-drying were effective in preserving the phenolic components and AA of dried jujubes with no significant effect (p<0.05) on AOC compared to fresh jujubes. However, sun-drying and oven-drying caused decreases in AA, T1 TF and AOC. Jujube fruit flesh color turned brown after sun-drying or oven-drying. There were significant negative correlations between BV and AA, TF or AOC, while positive correlations were detected between the antioxidants and AOC.