Lipase-mediated transformation of milk fat and other oils as affected by choice of substrates and continuous phase

Lipase-catalyzed esterification and acyl-transfer reactions in the presence and absence of organic solvents were optimized for modifying food lipids, and particularly, butteroil.; Substrate preferences for pancreatic lipase-mediated acyl-exchange reactions with butteroil were evaluated with a series of acyl donors and alcohol acceptors, ranging in size from 2-17 acyl or alkyl carbons. At elevated concentrations of acyl donors ({dollar}ge{dollar}400 {dollar}mu{dollar}mol g{dollar}sp{lcub}-1{rcub}{dollar} mixture), relative reactivities (reaction rates and % yield) were: triacylglycerols {dollar}>{dollar} fatty acid methyl esters {dollar}>{dollar} fatty acids. For acyl acceptors, relative reactivities were: primary alcohols {dollar}>{dollar} secondary alcohols {dollar}>{dollar} tertiary alcohols. Generally, alcoholysis reactions were faster than acidolysis reactions.; Mixtures of acetyl-donor substrates and olive oil triacylglycerols (TAG) were designed to undergo acyl-exchange reactions to produce acetylacylglycerols (AcAG). Triacetin was the most efficient acetyl-donor co-substrate followed by ethyl acetate. The greatest yields (approaching 90% theoretical maximum) of AcAG were observed at a molar ratio of triacetin:olive oil TAG of 1:2 catalyzed by Lipozyme IM-20 (immobilized Rhizomucor miehei lipase) at 1-3% (w/w) water and 80-85{dollar}spcirc{dollar}C.; Lipase-mediated acyl-exchange and acyl-transfer reactions were also evaluated in a series of organic solvents using butteroil, olive oil and model co-substrates. In selected acidolysis and interesterification reactions, solvents promoting single phase reactive mixtures served as better choices than those promoting multi-phase mixtures. When glycerol was used as an acyl-group acceptor, nonpolar solvents were most supportive of esterification, apparently because of the combined water-sorbing effects of glycerol and polar solvents, although this trend was partially enzyme-specific.; Lipase (Lipozyme) was active and stable in Supercritical carbon dioxide (SC-CO{dollar}sb2{dollar}) at 55{dollar}spcirc{dollar}C, 31.1 MPa up to 60 hr. Hydrolytic reactivity was greatly enhanced by an increase in a{dollar}sb{lcub}rm w{rcub}{dollar} of the enzyme from 0.11 to 0.57, while acidolysis reactivity reached a maximum at a{dollar}sb{lcub}rm w{rcub}{dollar} of 0.39. A selectivity for acyl-exchange over hydrolysis reaction was found at elevated pressure. For selected reaction mixtures, an added dimension of reaction selectivity was apparent in SC-CO{dollar}sb2{dollar} relative to more conventional reaction media.