Pelagic fish oil : methods for extraction and purification

Sammanfattning: The Pelagic fishes are a wide group of fishes that live in the open water. They could be divided in two groups depending on the size, the small forage fishes and the large predators. These fishes swim regularly and have muscles with high lipid content. There are two types of muscles in the fish. The red muscle that are used for slow and medium speed. The white muscle is used in high speed. Fish oil are extracted using different techniques. Wet pressing uses four steps. Cooking, pressing, decantation and centrifugation. It is a traditional method. Solvent extraction is performed with organic solvents. Supercritical fluid extraction uses the properties of the supercritical fluid to extract different substances. Enzymatic extraction uses the enzymes to break down the structure of the fish. Fishes are also a good source of healthy polyunsaturated fatty acids, such as eicosapentaenoicand docosahexaenoic acid. Pollutants in the water easily end up in the fish. These substances accumulate in food chain and are poisonous for humans. The crude oil contains impurities and has to be purified before consumption. There are several steps and methods to perform the purification. One common method is degumming, neutralization, bleaching, deodorization and winterization. These steps remove phospholipids, free fatty acids, metals, pigments, ions, metallic complexes, oxidation product and waxes. A combination of activated carbon and supercritical fluid extraction could remove pollutants with 100 %. Urea fractionation, chromatography and molecular distillation are methods to concentrate the refined oil.