Evaluation of different natural antioxidants as affecting volatile lipid oxidation products related to off-flavours in corn flakes

Different types of natural antioxidants (tocopherols – alone, in two different doses, or combined with ascorbic acid – and a rosemary extract) were employed in the production of corn flakes, to select the most effective ones for achieving low levels of volatile lipid oxidation products, related to off-flavours, after long-term storage. Samples were submitted to SPME/GC/MS and sensory analyses. Multivariate analysis elucidated the contribution of the volatile compounds to the sensory properties of corn flakes. Under the experimental conditions, tocopherols conferred better antioxidant activity than did rosemary extract, leading to low levels of off-flavour compounds, with a further improvement provided by the synergistic activity of ascorbic acid. This could be attributed to interfacial and phase partitioning phenomena involving antioxidants, depending on their lipo- or hydrophilicity, in heterogeneous food products. Acids, n-alkanols, lactones and some aldehydes appeared to have a considerable influence on the intensity of the off-flavours.