Interestification of Butterfat by Lipase from Rhizopus niveus in Reverse Micellar Systems

抄録

Butterfat was interesterified in phosphatidylcholine reverse micellar systems containing hexane at different ratios of water per mol surfactant (W₀), with a commercial lipase (Lipase N, Amano). The amount and composition of free fatty acids were found by gas-liquid chromatography. Triacylglycerols were separated from interestified butterfat by column chromatography on a Supelclean LC-SI column. The purified triacylgylcerols were separated analytically by high-pressure liquid chromatography. The positional distribution of fatty acids was identified by enzymatic deacylation with commercial pancreatic lipase. The addition of up to 2.2% water (W₀ = 17.4) to the reaction mixture had little effect on the interesterification yield, but shifted the reaction equilibrium in favor of hydrolysis by 4-fold. Further additions of water up to 4.4% (W₀ = 34.8) resulted in maximum yield, with a decreased degree of hydrolysis, from 2.2 to 1.8mmol of free fatty acids per gram of butter. The interesterified butterfat triacylglycerols had an increased amount of palmitic acid (C16 : 0) at the sn-2 position with a decrease in the proportions of small chain fatty acids (C4-C10).