Phenolic and flavonoid contents of mandarin (Citrus reticulata Blanco) fruit tissues and their antioxidant capacity as evaluated by DPPH and ABTS methods

The total phenolic and flavonoid contents in the fruit tissues (peels, pulp residues, seeds, and juices) of 19 citrus genotypes belonged to Citrus reticulata Blanco were evaluated and their antioxidant capacity was tested by 2,2-diphenyl-1-picrylhydrazyl radicals (DPPH) method and 2,2′-azino-bis(3-ethylbenzthiozoline-6)-sulphonic acid (ABTS) method. The total phenolic and flavonoid contents, and their antioxidant capacity varied in different citrus fruit tissues. Generally, the peel had both the highest average of total phenolics (27.18 mg gallic acid equivalent (GAE) g−1 DW) and total flavonoids (38.97 mg rutin equivalent (RE) g−1 DW). The highest antioxidant capacity was also the average of DPPH value (21.92 mg vitamin C equivalent antioxidant capacity (VCEAC) g−1 DW) and average of ABTS value (78.70 mg VCEAC g−1 DW) in peel. The correlation coefficient between the total phenolics and their antioxidant capacity of different citrus fruits tissues ranged from 0.079 to 0.792, and from −0.150 to 0.664 for the total flavonoids. The antioxidant capacity of fruit tissues were correlated with the total phenoilc content and flavonoid content except in case of the peel. In addition, the total phenolic content and antioxidant capacity varied in different citrus genotypes. Manju and Karamandarin were better genotypes with higher antioxidation and the phenolic content, however Shagan was the poorest genotype with lower antioxidation and the phenolic content.