Dissimilarity of the oxidations of rapeseed and butter oil triacylglycerols and their mixtures in the absence of tocopherols

Although fatty acid composition is the most important attribute used to con trol oxidation stability, all edible oils are affected by lipid oxidation i rrespective of whether they are highly unsaturated or not. The aim of the s tudy was to compare the oxidation of rapeseed oil (RO) and butter oil (BO) triacylglycerols (TAGs) and their mixtures containing 10% or 20% of the oth er. Oxidation of the TAGs at 40 degrees C was followed by formation of prim ary and secondary products. Statistical methods were used to interpret the data. The RO and BO TAGs and their mixtures began to oxidise without any in duction periods. In the RO TAGs more hydroperoxides and p-anisidine reactiv e compounds were formed than in the BO TBGs. The BO TAGs oxidised more than would be expected by their fatty acid composition. High susceptibility of BO TAGs to oxidation was caused by the easy breakdown of their hydroperoxid es. Heptadienal and heptenal were specific products of oxidised RO TAGs and heptanal and nonenal of oxidised BO TAGs. Mixtures of RO and BO TAGs behav ed according to which was dominant in the mixture. However, as little as 10 % of RO or BO TAG introduced its specific oxidation products to the mixture . (C) 1999 Society of Chemical Industry.