Docosahexaenoic acid purification from fish processing industry by‐products

Docosahexaenoic acid (DHA) is a well-known dietary n-3 polyunsaturated fatty acid (PUFA) found in marine fish and organisms whose beneficial effects for human health are widely reported. However, the supply of food containing DHA is currently becoming critical due to the overexploitation of fisheries worldwide. Consequently, searching for alternative sources of DHA is a relevant issue nowadays. Viscera from cultured fishes is considered a by-product by the fishery industry and therefore discarded after fish processing. In this work, viscera from farmed marine fish (Sparus aurata and Dicentrarchus labrax) and also oil extracted from such by-products have been studied to assess their suitability as DHA sources by obtaining their fatty acid profiles. Viscera oil was used as a source for DHA purification by a simple and easily scalable chromatographic method. As a result, a highly purified DHA fraction (>99.0% DHA on total fatty acids) was obtained. Practical applications: This DHA concentrate obtained from viscera oil could be potentially used for alimentary or pharmaceutical purposes due to its lower cholesterol content compared with other known marine sources and also because only safe and legally allowed food-grade solvents have been used throughout the whole process. This way, by obtaining a high added-value product, a revaluation is given to fish by-products which are usually discarded. Fatty acid profile of whole viscera oil (11.1% DHA of total FA) (left) and chromatogram of the DHA fraction after chromatographic purification (>99.0% DHA of total FA) (right) by using food-grade solvents as the mobile phase.