Hydrolysis of coconut oil (Cocos nucífera L.) by specificity and no positional specificity enzimes.

Abstract

The characteristic fatty acid composition of coconut oil provides mainly short- and medium- chain fatty acids when incorporated to the diet. These fatty acids have nutritional advantages because their metabolic disposition allows the rapid obtention of energy, mainly at the hepatic level. The obtention of short- and medium- chain fatty acids from coconut oil as substrate, may be of importance because the different nutritional, pharmacological, and technological uses of these fatty acids. In the present work, the effect of two type of lipases on the hydrolysis of coconut oil was studied; a lipase obtained from Candida cylindracea showing no positional specificity, and a lipase from Mucor miehei with sn-1',3' specificity in its free and immobilized form (Lipozyme IM-20). The lipase from Candida cylindracea allows the hydrolysis of 85%-90% of the triacylglycerols after 47-50 hours, the fatty acid composition of the hydrolyzate being similar to the composition of the oil. The remaining monoacylglycerols show a prevalent composition of short- (C6-C8) -and medium- chain (C10-C14) fatty acids. Lipase from Mucor miehei allows 65% of hydrolysis, which is obtained after 30 hours of incubation when the free form of the lipase is assayed, and after 10 hours for the immobilized form (Lipozyme IM-20). The fatty acid composition of the hydrolyzate is similar for the two enzymes and different to the composition of the oil, being C8-C14 the most prevalent fatty acids. The remaining monoacylglycerol, as product of the action of both forms of the enzyme, is almost enterely composed by lauric acid (C12:0), implicating that the sn-2' position is the most favoured for this fatty acid in the coconut oil triacylglycerols. The usefulness of lipases for the obtention of especific fractions of some fatty acids is discussed. The utility of the lipase from Mucor miehei for the obtention enriched fractions of lauric acid, which can be liberated after saponification, is also discussed.