The awareness of health benefits of marine lipids with a high content of omega-3 poly unsaturated fatty acids from fish and algae oil has led to an increased intake as oil and in products. However, these lipids are highly susceptible to lipid oxidation, which results in the formation of undesirable off-flavours and gives rise to unhealthy compounds such as free radicals and reactive aldehydes.
Necessary prerequisites for successful development of omega-3 enriched products are that the oil used for enrichment is of a high quality and low in oxidation products and that oxidation of the lipids is prevented both during production and storage.
In complex products, lipid oxidation and antioxidant mechanisms are very complex, due to the many factors that can influence the rate and extent of lipid oxidation. In order to obtain and maintain a good quality and oxidative stability of omega-3 oil and enriched foods, oxidation may be minimised by optimising by both intrinsic (physico-chemical) and extrinsic factors. Intrinsic factors are e.g. addition of antioxidants, choise of emulsifier and droplet size. Extrinsic factors, such as exposure to light, high temperature and oxygen, cause increased oxidation. As processing will often cause extra oxidative stress to the omega-3 oil, extrinsic factors are especially important to consider during processing. Due to the complexity of multiphase foods, it is very difficult to predict the oxidative stability and therefore the behaviour and efficacy of antioxidants in omega-3 oil enriched products and optimal composition and processing conditions must be evaluated for each product.