Fish products and Byproducts Technology

Unit 9 - Fish meal and fish oil

9.8. Fish oil
Introduction
Fish oils may generally be described as flesh oil, liver oil, or oil of the whole fish. It can be the by product in fish meal plant or may be the target product in fish oil production plant. The product, however, is versatile and finds many applications in the food and technical industries and is still of considerable economic importance to producers.
Chemical structure of fish oil
It mainly consists of triglycerides of fatty acids (glycerol combined with three similar or different acid molecules) with variable amounts of phospholipids, glycerol ethers and wax esters. It is characteristic of the oils that they contain a wide range of long-chain fatty acids with the number of carbon atoms ranging mainly from 14 to 22, and high degree of reactivity (unsaturation) ranging up to six double bonds per molecule.
Raw material
According to the Food and Agriculture Organization (FAO) raw material used for the production of fish oil falls into three categories:

• Fish caught specifically for reduction to fishmeal and fish oil such as menhaden, anchovy, capelin and sardines.
• Incidental or by catch from another fishery (for example the global discards amounted to 27.0 million metric tons (mmt) with a range of from 17.9 to 39.5 mmt with shrimp by catch accounting for 11.3 mmt)
• Fish by-products from the edible fisheries such as cuttings from filleting operations, fish cannery waste, roe fishery waste and more recently surimi processing waste.