An effort to improve the shelf life of breakfast cereals using natural mixed tocopherols

An experimental investigation was carried out with the aim of appraising the effects of natural tocopherols on lipid oxidation in extruded breakfast cereals. Corn flakes produced on an industrial scale, with and without added tocopherols and stored in commercial packing under shelf conditions, were compared using sensory evaluation and analyses of volatile compounds and triacylglycerol polymerization products. The sensory evaluation showed the effectiveness of tocopherols in limiting the development of off-flavour during storage. The analysis of the volatile compounds, focused on the secondary products of the lipid oxidation, showed that the antioxidant activity of tocopherols limited the evolution of the headspace towards a more intense oxidation, notably the further oxidation of hexanal into hexanoic acid (that reached 32% and 15% in the flakes, respectively, without and with added tocopherols, after 360 days). The percentage of hexanoic acid in the headspace positively correlated with almost all the descriptors of the defect considered for the sensory evaluation. The analysis of the triacylglycerol polymerization products confirmed the inhibiting action of tocopherols on lipid oxidative degradation.