Marine (n-3) polyunsaturated fatty acids

Abstract

Marine fish oils have been intensively studied for many years because of their commercial value and their special chemical properties that stem from their high content of very long-chain polyunsaturated fatty acids (PUFA) of the (n-3) series. The high content of (n-3) PUFA gives marine fish oils the special drying properties that were traditionally exploited for the production of paints and varnishes. However, in modern times, the major commercial outlet for fish oils was and continues to be as foodstuffs for man and farmed livestock. In the 1970s and 1980s, marine oils accounted for only 2% of the total world production of edible fats and oils, the remaining 98% being accounted for by vegetable oils (68%) and animal fats (30%).1 In 1992, one million metric tons of fish oil were produced worldwide against a global total fat and oil production of 84 million metric tons, 10% of which was animal tallow and grease. Commercial fish oils are consumed in human foods mostly as partially hydrogenated fish oil (PHFO) in margarines, shortenings and fillers. For example, in 1981 fish oils accounted for 56% of the total oils used for margarine production in the UK.2 Partial hydrogenation eliminates problems of instability due to peroxidation of PUF A in the original oils and also generates a final product with useful properties of plasticity and phase transition temperature (melting point).