The production of monoglycerides by glycerolysis of olive oil catalyzed by lipases from Candida rugosa, a~ Chromobacterium viscosum and Rhizopus sp. immobilized in C12:0 a hydrophylic polyurethane foam was investigated. The effect C14:0 of the amount of aqueous phase used for foam polymerization C18:1 on the competing reactions of glycerolysis and hydrolysis was DG studied. The highest monoglyceride production was achieved FAME with the C. rugosa lipase which was thus selected for FFA subsequent studies. FID The extent to which hydrolysis and glycerolysis occur and Gly the influence of the initial aw of the system on both reactions n were also investigated. In glycerolytic reaction systems, initial MG rates of fatty acid release were always higher than in hydrolytic PCA systems. At aw values lower than 0.43, hydrolysis was PU completely repressed, although glycerolysis still occurred. This r suggests that hydrolysis of the ester bond in the glyceride, TG promoted by glycerol, is the first reaction step. TO In glycerolysis, initial rates of FFA and DG production increased exponentially with the initial a,~ of the system.
The lowest total conversion (in terms of % TG consumed) at 48 hours was obtained at intermediate a~ values; higher conversions at extreme aw indicated an increase in hydrolytic and glycerolytic rates, at high and low a,~, respectively.
The yield of MG increased with decreasing a~. The highest yield of MG (~ 70%, w/w) was obtained at the lowest aw used (0.23). The initial a~ of the reaction system is an important parameter in glycerolysis.