Antioxidant capacity of cow milk, whey and deproteinized milk

The total antioxidant capacity (hydrophilic plus lipophilic) of sixteen different commercial samples of pasteurized and ultra high temperature (UHT) treated milk was determined using the oxygen radical absorbance capacity assay using fluorescein as a fluorescent probe. A significant correlation between the percentage of fat and the value of the total antioxidant capacity was found in milk samples obtained from the same batch of raw milk. Analyses of the whole milk, whey and deproteinized milk showed that the major contributor to the total antioxidant capacity of whole milk was the casein fractions, while albumin was the major contributor to the total antioxidant capacity of whey protein. Hydrophilic antioxidant compounds, such as vitamin C and uric acid, were the main contributors to the total antioxidant capacity of the deproteinized milk. Significant differences in total antioxidant capacities were found between whey and deproteinized samples obtained from pasteurized and UHT-treated milk, the values being higher for the former.