Comparison of total antioxidant capacity and phenolic composition of some apple juices with combined HPLC–CUPRAC assay

It was aimed in this study to identify and quantify various constituents (particularly phenolics) of apple juice and to quantitatively compare the total antioxidant capacities of juices obtained from apple varieties grown in Turkey.Experimental studies were performed by determining the total antioxidant capacities using two spectrophotometric methods, cupric ion reducing antioxidant capacity (CUPRAC) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonate) (ABTS) methods, and by identification and quantification of the leading antioxidant constituents individually with HPLC. The total antioxidant capacity (TAC) values of HPLC-quantified antioxidant constituents were found, and compared with those found by CUPRAC and ABTS. The TAC of HPLC-quantified compounds accounted for between 40.0% and 70.6% of the observed CUPRAC capacities of apple juices with respect to apple varieties.The order of antioxidant capacity of apple juices determined by the CUPRAC and ABTS methods were: Ervin Spur > King Luscious > Sky Spur > Amasya > Arap Kizi ⩾ Granny Smith > Lutz Golden.