Antioxidant Activity of an Ultrafiltration Permeate from Acid Whey

Acid whey inhibited up to 90% of iron‐catalyzed oxidation of phosphatidylcholine liposomes. Ultrafiltration, dialysis, heat treatment and chloroform extraction indicated that the primary antioxidant(s) in acid whey were polar, heat‐stable compound(s) with molecular weights between 500 and 5,000. Lipid oxidation catalysts, including iron, lipoxidase, photoactivated riboflavin and hydrogen peroxide‐activated metMb, were inhibited by acid whey and its ultrafiltration permeate. The antioxidant activity of the UF permeate increased with increasing pH (5.4–7.0). These data suggest that acid whey and its UF permeate could be used as a “natural” antioxidant.