Assessment of lipase- and chemically catalyzed lipid modification strategies for the production of structured lipids

The purpose of the present study was to devise a two-step reaction to produ ce partial glycerides, which would subsequently be used as substrates in bo th lipase-catalyzed and chemically catalyzed esterification reactions with caprylic acid. The yields and kinetics of these two-step reactions were com pared to established lipase-catalyzed acidolysis and transesterification as well as to chemical transesterification reactions. Acyl migration did not occur during the hydrolysis or short-path distillation steps in the prepara tion of free fatty acid-free partial glycerides for esterification reaction s. No significant differences in final yields (59.9% to 82.8% w/w of total triacylglycerols) of new structured lipids were detected among lipase-catal yzed (24 h) and chemically catalyzed (5 h) reactions; however, the yield of new structured triacylglycerols (TAG) after 2 h was lower for acidolysis t han for the other lipase-catalyzed reactions (P less than or equal to 0.05) . Since no differences in final yields were detected among the reactions, c hemical esterification using hydrolyzed oil could represent the best synthe tic option, since it offers the advantage of positional distribution contro l associated with lipase-catalyzed reactions as well as rapid reaction time s associated with chemically catalyzed reactions. Attempts to evaluate the positional distribution of caprylic acid using allyl magnesium bromide (Gri gnard reagent) were hampered by production of unknown species, which preven ted accurate determination of the concentration of some key fatty acids.