EFFECTS OF SUPPLEMENTAL IRON AND COPPER ON LIPID OXIDATION IN MILK .2. COMPARISON OF METAL-COMPLEXES IN HEATED AND PASTEURIZED MILK

The preceding paper showed that lipid oxidation in iron-and copper-supplemented dairy products can be reduced by the use of chelated forms of iron(III) and copper(II). Prolonged batch heating increased the susceptibility of raw milk to oxidation by chelated iron (III) but decreased oxidation by ferrous salts. Oxidation produced by a given metal complex was about the same whether the metal was added before or after heat treatment. Oxidation was affected very little by brief heating or by lengthening the interval between addition of iron and pasteurization by a high-temperature/short-time process. With any of the heating variables tested, the iron(III) chelates of nitrilotriacetate and lactobionate catalyzed less oxidation than ferrous salts. In order to minimize reactions leading to oxidative deterioration in fortified milk, the data indicate that the addition of chelated iron(III) and copper(II) should be made after homogenization (to emulsify and protect the milk fat fraction) but before pasteurization by a high-temperature/short-time process. © 1979, American Chemical Society. All rights reserved.