title: Synthesis of 2-monoacylglycerols and structured triacylglycerols rich in polyunsaturated fatty acids by enzyme catalyzed reactions.
abstract: This paper studies the synthesis of structured triacylglycerols (STAGs) by a four-step process: (i) obtaining 2-monoacylglycerols (2-MAGs) by alcoholysis of cod liver oil with several alcohols, catalyzed by lipases Novozym 435, from Candida antartica and DF, from Rhizopus oryzae, (ii) purification of 2-MAGs, (iii) formation of STAGs by esterification of 2-MAGs with caprylic acid catalyzed by lipase DF, from R. oryzae, and (iv) purification of these STAGs. For the alcoholysis of cod liver oil, absolute ethanol, ethanol 96% (v/v) and 1-butanol were compared; the conditions with ethanol 96% were then optimized and 2-MAG yields of around 54-57% were attained using Novozym 435. In these 2-MAGs, DHA accounted for 24-31% of total fatty acids. In the operational conditions this lipase maintained a stable level of activity over at least 11 uses. These results were compared with those obtained with lipase DF, which deactivated after only three uses. The alcoholysis of cod liver oil and ethanol 96% catalyzed by Novozym 435 was scaled up by multiplying the reactant amounts 100-fold and maintaining the intensity of treatment constant (IOT=3g lipase h/g oil). In these conditions, the 2-MAG yield attained was about 67%; these 2-MAGs contained 36.6% DHA. The synthesized 2-MAGs were separated and purified from the alcoholysis reaction products by solvent extraction using solvents of low toxicity (ethanol and hexane); 2-MAG recovery yield and purity of the target product were approximately 96.4% and 83.9%, respectively. These 2-MAGs were transformed to STAGs using the optimal conditions obtained in a previous work. After synthesis and purification, 93% pure STAGs were obtained, containing 38% DHA at sn-2 position and 60% caprylic acid (CA) at sn-1,3 positions (of total fatty acids at these positions), i.e. the major TAG is the STAG with the structure CA-DHA-CA.
authors: Department of Chemical Engineering, University of Almería, 04120 Almería, Spain.
authors: Alicia
authors: A
authors: Rodríguez
authors: Luis
authors: L
authors: Esteban
authors: Lorena
authors: L
authors: Martín
authors: María José
authors: MJ
authors: Jiménez
authors: Estrella
authors: E
authors: Hita
authors: Beatriz
authors: B
authors: Castillo
authors: Pedro A
authors: PA
authors: González
authors: Alfonso
authors: A
authors: Robles
mesh_terms: D001709:Biotechnology / Q000379:methods; D002175:Candida / Q000201:enzymology; D002384:Catalysis; D003060:Cod Liver Oil / Q000378:metabolism*; D004951:Esterification; D000431:Ethanol / Q000378:metabolism; D005231:Fatty Acids, Unsaturated / Q000032:analysis*; D008049:Lipase / Q000378:metabolism*; D050178:Monoglycerides / Q000737:chemistry / Q000378:metabolism*; D012233:Rhizopus / Q000201:enzymology; D014280:Triglycerides / Q000737:chemistry / Q000378:metabolism*
chemical_list: D005231:Fatty Acids, Unsaturated; D050178:Monoglycerides; D014280:Triglycerides; D000431:Ethanol; D003060:Cod Liver Oil; D008049:Lipase