Application of and correlation among antioxidant and antiradical assays for characterizing antioxidant capacity of berries

Various antioxidant assays are used to characterize fruits consumed fresh or processed although an easy, reliable and cheap assay is not available to follow the changes in antioxidant power. This study tested the applicability of a recently developed antioxidant measuring system, Water-soluble (ACW) and Lipid-soluble (ACL) Antioxidant Capacity, using the PHOTOCHEM^® instrument. Initially, 13 cultivars of 4 berry species were assayed with Photochem and compared with widely used methods based on single electron transfer reactions like ferric reducing ability of plasma, total polyphenolic content (TPC) and 2,2′-diphenyl-1-picrylhydrazyl radical-scavenging capacity. Assays based on hydrogen atom transfer reactions were also carried out including total radical-scavenger capacity (TRSC). The correlations among the results were all significant at P ≤ 0.05, except the one between TPC and ACW. The overall antioxidant capacity ranked on the order of strawberry < red currant < raspberry < black currant. However, significant differences could have been detected among genotypes and antioxidants assays used for the analysis. The Photochem instrument is not suitable for easy, cheap and high-throughput routine analysis of berry antioxidant capacity and hence is not preferable to other assays.