Antioxidant capacity of fresh, sun- and sulphited-dried Malatya apricot (Prunus armeniaca) assayed by CUPRAC, ABTS/TEAC and folin methods

Abstract

Apricots as five varieties of Malatya region have been assayed as fresh, sun- and sulphited-dried samples, using the antioxidant capacity measurement methods Cupric Ion Reducing Antioxidant Capacity (CUPRAC) and 2,2'-azinobis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), and total polyphenol measurement method Folin. The novel reagent for the CUPRAC total antioxidant capacity assay, bis(neocuproine)copper(II) chloride, was easily accessible, stable, selective and responding to all antioxidants. Sulphite (normally contributing to the colour formed in the CUPRAC assay) was removed prior to assay on a strongly basic anion exchanger at pH 3 in the form of HSO3-. The CUPRAC findings correlated well with the results of ABTS/TEAC and Folin assays (r = 0.93), all being electron-transfer-based antioxidant capacity assays. The calibration lines of pure flavonoids individually and in standard-added apricot extracts were parallel, indicating the additivity of absorbances in CUPRAC. This work reports for the first time the use of a novel spectrophotometric method (CUPRAC) for the assay of both total antioxidant capacity and sulphite levels of diverse apricot samples.