| Summary: | Synthesis of high-purity (>99%) monostearin was carried out using a two-step process. The first step involved lipase-assisted enzymatic esterification of fatty acid with glycerol catalyzed by immobilized lipase Candida antarctica (Novozym, 435) in acetone. The reaction was carried out at a fatty acid (FA) to glycerol molar ratio of 1:4 with 5% lipase based on the fatty acid (FA) weight. Equilibrium was attained within 8 h with a nionoglyceride (MG) content and a degree of esterification of 82.4 wt% and 85.5%, respectively. The addition of solvent shifted the equilibrium toward product formation and resulted in further increases of the MG content and the degree of esterification to 89.7 wt% and 92.7%, respectively, after 16 h (total: 24 h). The major impurities in the reaction product were free fatty acids (up to 7 wt%) and di- and triglycerides (<3.5%). The second step involved the removal of fatty acids by a mild alkali treatment, and it produced MG with purity greater than 99 wt% and an overall yield of 66.8%. Comparison of various solvents shows that the extent of esterification and product selectivity are strongly dependent on the solubility-solvation of the substrate and product in the reaction medium. Thus, monoglycerides was carried out using monostearin synthesis as model system in this investigation.
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