Lipase‐catalyzed esterification of glycerol and oleic acid

Abstract

The enzymatic synthesis of glycerides from glycerol and oleic acid in organic solvent was studied, and the optimal conditions for glyceride synthesis by lipases were established. Of the commercially available lipases that were investigated, Candida rugosa lipase and porcine pancreas lipase resulted in the highest extent of esterification. Iso-octane and hexane were particularly useful organic solvents in glyceride synthesis. The water content in the reaction mixture was of primary importance. For C. rugosa lipase and porcine pancreas lipase, the optimal water contents were 5 and 1%, respectively. Candida rugosa lipase and porcine pancreas lipase manifested contrasting positional specificities in glyceride synthesis.Esters of glycerol with FA occur naturally in fats and oils, and they are widely used for edible and industrial purposes. The modification of fats and oils and the production of glycerides from glycerol and FA promise the development of new oil and fat compounds that possess new properties in comparison with the original materials. Conventional esterification of glycerol to produce MG, DG, and TG by chemical catalysts requires high temperatures and leads to dark-colored products and undesired by-products (1).Using enzymes to catalyze these reactions is superior to using conventional chemical methods owing to their mild reaction conditions, high catalytic efficiency, and inherent selectivity, which result in much purer products. The use of lipolytic enzymes to catalyze the esterification reaction has been investigated by many workers (2-8). Lipases are present in high activity in the reserve tissue of many oilseed plants (9). Some lipases catalyze only the hydrolysis reaction of fats and oils, whereas others show catalytic activity on both the hydrolysis and esterification reactions.In this study, the synthesis of glycerides from glycerol and oleic acid in organic solvent by lipases was studied, and the effects of process parameters such as organic solvents, water content, glycerol content, and temperature were investigated. EXPERIMENTAL PROCEDURESMaterials. Nonspecific Candida rugosa lipase and 1,3-positional specific porcine pancreas lipase (PPL), oleic acid, and glycerol were purchased from Sigma Chemical Co. (St. Louis, MO). All solvents used in this work were of analytical grade and were obtained from Merck (Darmstadt, Germany).Esterification reaction. Reaction mixtures for glyceride synthesis from glycerol and oleic acid consisted of: glycerol, 2 g (about 20 mmol); oleic acid, 0.5 g (about 2 mmol); water, 150 µL; and n-hexane, 3 mL. Reaction mixtures were placed in 50-mL Erlenmeyer flasks with silicone-capped stoppers to prevent evaporation of the reactants. The reaction was started by the addition of 0.1 g lipase in the form of dry powder. The suspension that resulted was agitated on an orbital shaker at 200 rpm at 30°C. At various times during incubation, 0.2 mL of the reaction mixture was withdrawn and analyzed by TLC and GC.Estimation of the degree of synthesis. The reaction was stopped by add...

Lipase-Catalyzed Synthesis of Diacylglycerol and Monoacylglycerol from Unsaturated Fatty Acid in Organic Solvent System

“…Where as in the presence of enzymes, the same reactions may be carried out at reasonable lower temperature and atmospheric pressure without discoloration and production of undesired by-products. The use of lipolytic enzyme to catalyze the esterification reaction has been investigated by many workers (4)(5)(6)(7)(8)(9). Diacylglycerols (DAG) and Monoacylglycerols (MAG) are potentially attractive starting materials for numerous synthetic applications (10)(11).…”

Enzymatic selective synthesis of 1,3-DAG based on deep eutectic solvent acting as substrate and solvent

“…Reaction conditions 10 g total reactant amount, 2:1 molar ratio oleic acid/ glycerol, 0.4 g Novozym 435, 1.2 g 4 Å molecular sieves, 50°C, 250 rpm. The molar ratios of ChCl to glycerol were 1:1, 1:1.5, 1:2 and 1:2.5, respectively and higher extent of esterification efficiency of oleic acid can be obtained [34]. Hence, higher concentrations of glycerol would lead to a higher MAG production.…”

“…Quaternary ammonium compounds mixing with hydrogen bond donor under different molar ratio can form DESs with different characteristics [34]. The enzyme selectivity in ChCl adding system with different content of ChCl was shown in Fig.…”

“…6). Tripathi et al [41] reported total DAG concentration of 33.1 % through the esterification of oleic acid with glycerol in n-hexane system catalyzed by lipase RMIM at 72 h. Yesiloglu and Kilic [34] reported total DAG concentration of 39.3 % from the esterification of oleic acid with glycerol in n-hexane system catalyzed by C. rugosa lipase at 24 h. Rosu et al [42] reported 1,3-DAG concentration of about 61 wt% from the esterification of oleic acid with glycerol catalyzed by RMIM in solvent free system at 12 h. Duan reported N435-catalyzed 1,3-DAG preparation via esterification in t-butanol system, a 1,3-DAG concentration of 40 % was achieved at 7 h [22]. Liu reported a fast synthesis of 1,3-DAG by Lecitase Ultracatalyzed esterification in solvent-free system; 54.8 wt% of 1,3-DAG can be obtained at 1.5 h [20].…”

Production of Glyceryl Monostearate by Immobilized Candida Antarctica B Lipase in Organic Media

“…The effects differ depending on the kind of organic solvents and enzymes used. Conformational changes in enzymes have been reported to result in alteration of substrate specificity and affinity of substrates for enzymes [18,21,23]. In this work, several organic solvents with different log P values were screened for their effect on synthesis of glyceryl monostearate.…”