Modification of the ferric reducing antioxidant power (FRAP) assay to determine the susceptibility of raw milk to oxidation

The susceptibility of raw milk towards oxidized flavor development is a serious concern to dairy farmers and processors. The objective of the present research was to investigate the applicability of the ferric reducing ability of plasma (FRAP) assay for identification of raw milk that is susceptible to oxidation. The original FRAP assay was modified accordingly for raw milk analysis. Subsequently, the influence of antioxidants and pro-oxidants on the total antioxidant capacity of raw milk during refrigerated storage was evaluated using the modified FRAP assay. Raw milk spiked with copper, vitamin E, and their combination significantly influenced the FRAP value of raw milk. Also, the FRAP value of raw milk with no additives diminished during refrigerated storage. A total of 647 samples were analyzed at a commercial facility using the modified FRAP assay and could identify low FRAP value routes and communicated with the farms in an attempt reduce the consumer complaints. (C) 2013 Elsevier Ltd. All rights reserved.