Lipophilized phenolics as antioxidants in fish oil enriched food systems

Food products containing long chain omega-3 PUFA are highly susceptible to oxidation, which causes undesirable flavors and loss of health beneficial fatty acids. Many omega-3 enriched food products on the market are oil-in-water emulsions. According to the so called “polar paradox”, polar compounds work better as antioxidants in bulk oil, whereas lipophilic compounds are better antioxidants in emulsions. Phenolics have in general shown to posses antioxidative properties, which depend upon their structure i.e. number and location of –OH groups. However, many of these compounds are polar. Our hypothesis is that lipophilization of such polar phenolic compounds may improve their efficacy in fish oil enriched food systems. Our study aimed at evaluating rutin and dihydrocaffeic acid and their esters as antioxidants in o/w emulsion model system and milk enriched with fish oil. Moreover, the effect of the chain length of the fatty acid was investigated. The effect of the compounds was evaluated by determination of primary and secondary oxidation products. Further, these findings were combined with antioxidant assay and partitioning studies. Preliminary data showed that the lipophilization improve the antioxidative effect depending on the system, and that the chain length influenced the efficacy of the lipophilized compounds.