title: 13C NMR quantification of mono and diacylglycerols obtained through the solvent-free lipase-catalyzed esterification of saturated fatty acids.
abstract: In the present investigation, we studied the enzymatic synthesis of monoacylglycerols (MAG) and diacylglycerols (DAG) via the esterification of saturated fatty acids (stearic, palmitic and an industrial residue containing 87% palmitic acid) and glycerol in a solvent-free system. Three immobilized lipases (Lipozyme RM IM, Lipozyme TL IM and Novozym 435) and different reaction conditions were evaluated. Under the optimal reaction conditions, esterifications catalyzed by Lipozyme RM IM resulted in a mixture of MAG and DAG at high conversion rates for all of the substrates. In addition, except for the reaction of industrial residue at atmospheric pressure, all of these products met the World Health Organization and European Union directives for acylglycerol mixtures for use in food applications. The products were quantified by (13)C NMR, with the aid of an external reference signal which was generated from a sealed coaxial tube filled with acetonitrile-d3. After calibrating the area of this signal using the classical external reference method, the same coaxial tube was used repeatedly to quantify the reaction products.
authors.affiliation: Laboratório de Aplicações da RMN, Departamento de Química Orgânica, Instituto de Química, Universidade Federal Fluminense, Rua Outeiro de São João Batista s/n°, CEP: 24020-150, Niterói, Rio de Janeiro, Brazil.
authors.forename: Jane Luiza Nogueira
authors.initials: JL
authors.lastname: Fernandes
authors.forename: Rodrigo Octavio Mendonça Alves
authors.initials: RO
authors.lastname: de Souza
authors.forename: Rodrigo Bagueira
authors.initials: RB
authors.lastname: de Vasconcellos Azeredo
mesh_terms: D002138:Calibration; D002247:Carbon Isotopes; D002384:Catalysis; D004075:Diglycerides / Q000032:analysis* / Q000138:chemical synthesis / Q000737:chemistry; D004951:Esterification; D005227:Fatty Acids / Q000737:chemistry*; D008049:Lipase / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D050178:Monoglycerides / Q000032:analysis* / Q000138:chemical synthesis / Q000737:chemistry; D012015:Reference Standards; D012997:Solvents
chemical_list: D002247:Carbon Isotopes; D004075:Diglycerides; D005227:Fatty Acids; D050178:Monoglycerides; D012997:Solvents; D008049:Lipase