Effects of fish oil type, lipid antioxidants and presence of rapeseed oil on oxidative flavour stability of fish oil enriched milk

As a part of our ongoing experiments on optimization of the oxidative stability of fish oils in genuine food systems, this study investigated the oxidative deterioration of fish oil enriched milk emulsions during cold storage. The experimental data showed that addition of rapeseed oil to fish oil (1:1) prior to emulsification into milk significantly protected the emulsions against oxidative deterioration. Addition of propyl gallate and a citric acid ester to the fish oil prior to emulsification also protected the fish oil enriched milk during storage. Emulsions containing a rapeseed:fish oil mixture were oxidatively stable during 11 d at 2 degreesC. Thus, no additional inhibitory effect of the added antioxidants was observed. The peroxide value and concentrations of five selected volatiles derived from n-3 PUFA degradation in rapeseed:fish oil mixture emulsions were not significantly different from the corresponding levels in neither the emulsion containing only rapeseed oil nor the milk. It is proposed that the tocopherols in rapeseed oil may be the protective factor. Three-way chemometric exploratory data analysis was implemented in form of a parallel factor analysis (PARAFAC). The PARAFAC model provided an overview of the obtained data with significantly enhanced interpretability, and revealed information about groupings and correlations in our data.