Electrochemical studies on antioxidants in bovine milk

Cyclic voltammetry (CV), rotating disk electrode (RDE) linear sweep voltammetry and flow-injection amperometry (FI-Amp) were used to investigate the possibility to determine antioxidants in bovine milk, whey and low-molecular-weight (LMW) fractions of whey. Using CV one major current wave was found in all types of samples at oxidation potentials between +600 and +700 mV against Ag\AgCl\0.1 mol l(-1) KCl. The wave registered for the LMW fraction disappeared after treatment with uricase as shown by CV and RDE, indicating that the major antioxidant in the LMW fraction may be urate. The antioxidant capacities of the LMW fractions were also measured by the FIAmp method using an oxidation potential of +700 mV with Trolox as standard, and values between 100 and 130 mumol l(-1) Trolox equivalents were obtained. It is concluded that different electrochemical methods can be used to measure antioxidants in milk. (C) 2002 Elsevier Science B.V. All rights reserved.