Comparison of antioxidant capacity of milk, defatted milk, whey, and deproteinized whey from cow, sheep, and goat, and effect of thermal treatments.

Antioxidant potential of different milk types and thermal-treated milks may be of interest to milk processors, consumers, and nutritionists. The objectives of this study were comparison of the antioxidant potential of milk, defatted milk, whey, and deproteinized whey from cow, sheep, and goat, and also evaluation of the effect of thermal treatments (pasteurization and sterilization) on the antioxidant activity of the milk. The antioxidant potential of different milk samples and their fractions was examined using reducing power, 2,2-diphenyl-1-picrylhydrazyl, and 2,2-azinobis-3-ethylenzothiazoline-6-sulphonicacid methods. The results showed that the antioxidant potential of sheep raw milk was significantly higher than that of cow milk and goat milk. The results also indicated that thermal processing increased the reducing power and antioxidant potential of milk, and increasing heating temperature significantly increased reducing power and 2,2-diphenyl-1-picrylhydrazyl scavenging activity of milk, especially sheep milk and goat milk. Removing of whey proteins from whey of all animal species, particularly sheep, caused a significant decrease in the antioxidant potential of whey. The results of this study showed that sheep milk and its fractions are a good source of natural antioxidants, which may have higher health promotion effects on consumers from nutritional point of view.