KINETICS OF OXIDATION OF DEHYDRATED FOOD AT LOW OXYGEN PRESSURES

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Abstract
Kinetic studies were performed to obtain the dependence of rates of lipid oxidation on O2 pressure, in a system containing free and adsorbed O2. The model system consisted of methyl linoleate dispersed on microcrystalline cellulose or on nonfat milk powder. Oxidations were carried out at 37.degree. C and with headspace concentrations of O2 ranging from 0.52-10.7%. These concentrations were maintained approximately constant by periodically resupplying O2 to replace the amount reacted with the lipid. Bimolecular oxidation kinetics were found in both systems with the rate of oxidation more rapid (by a factor of 5-6) in the cellulose system. The dependence of oxidation on O2 pressure was of a form previously found for oxidizing lipids by other investigators and is consistent with theoretical considerations. The slower oxidation in the milk system appeared to be due to 2 factors: encapsulation of part of the lipid in the milk solids and the lower internal surface area of the milk solids compared to the cellulose support.