Lipase Mediated Interesterification of Triglycerides

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Research into the catalytic modification of triglycerides by lipolytic enzymes is underway. The objective is to clearly delineate the enzymatic action of lipases on lipid substrates in systems with minimal water content. Experiments will be conducted on the interesterification of two model triglycerides, tripalmitin, and triolein, a specific example of a reaction involving lipid modification by lipases. The experiments will examine and compare two alternate modes of substrate-enzyme contact (a) through enzymic reaction in organic solvents, and (b) through enzymic reaction in biphasic reversed micellar solutions. The studies will be directed to determine conditions for optimal lipase activity in essentially non-aqueous systems, with maintenance of a high selectivity to interesterification over hydrolysis. The role of organic solvents, the effects of water content and buffer ionic strength, colipase effects, substrate specificities, and cation levels are various system parameters to be considered. A thermodynamic framework for optimal solvent design and selection will be developed, based on modified solubility parameter criteria. Recent developments in gas chromatography will be applied involving heat-stable capillary columns and on-column injection techniques, to facilitate rapid analyses of triglyceride mixtures. Liapases have traditionally been recognized for their ability to break down triglycerides through hydrolysis. They have, therefore, been studied extensively for their medical relevance to atheroschlerosis and their industrial relevance to the production of long chain fatty acids from vegetable oils. It is only in recent years that their ability to function effectively in low water content systems has been recognized. Under such conditions, lipase action is one of lipid synthesis and modification, rather than lipid breakdown. Tremendous possibilities exist for lipase catalyzed biomodification and biosynthesis of several oleochemicals of importance to the pharmaceutical, food, and specialty chemicals industries. The synthesis of esters for example, has applications to the production of biocompatible surfactants that are important as emulsifiers in food, cosmetics, and pharmaceuticals. The interesterification reaction, the focus of the present research, involves fatty acid interchange between two triglycerides and has direct application to the production of high value edible oils, such as cocoa butter substitutes. The understanding of lipase action in lipid modification is still limited; it is the objective to further this understanding through a comprehensive study of a specific reaction. Long term directions for the research on lipases will focus on applying the fundamental knowledge acquired through this project to a variety of novel reactions involving lipid modification and synthesis.