Process optimization for the removal of environmental contaminants from fish oils

Fish oils are rich in nutritionally valuable omega-3 components, mainly eicosapentaenoic (EPA) and docosahexaenoic (DHA) fatty acids. Unfortunately, they could also be contaminated with a series of toxic pollutants like PCDD/Fs and PCBs. This article focuses on the methods for removal of these unwanted compounds and at the same time preserving the nutritional quality of fish oil. Adsorption, deodorization, packed column stripping, and a combination of processes are reviewed here. Activated carbon at 0.5% dosage was efficient in adsorbing PCDD/Fs and no- PCBs, but only 58% of the mo- PCBs could be removed. Adsorption treatment did not significantly alter the quality of the oil. Simple packed column stripping and/or deodorization removed no-PCBs, and especially mo-PCBs in a better manner, its efficiency increasing with temperature. Nutritional properties were preserved until 210°C, beyond which significant EPA and DHA degradation was observed. Combination of activated carbon treatment and deodorization was a good method to remove contaminants, yet preserving the nutritional quality of fish oil. At deodorization temperature of 190°C and 0.1% AC dosage, the total contamination level of PCDD/Fs and dioxin-like PCBs could be reduced, independent of the process sequence, from 35 to below 10 pg TEQ/g, in accordance with the European Union (EU) regulation