title: Study of different reaction schemes for the enzymatic synthesis of polyglycerol polyricinoleate.
abstract: BACKGROUND
  Different strategies for the solvent-free enzymatic production of polyglycerol polyricinoleate (PGPR) were explored in an attempt to simplify and improve the process. Besides the conventional procedure (obtaining polyricinoleic acid, followed by its esterification with polyglycerol), two alternative methods are proposed: (1) reversing the synthesis order, i.e. esterification of polyglycerol with ricinoleic acid and then the condensation of ricinoleic acid with the previously obtained polyglycerol ester; and (2) the enzymatic synthesis of PGPR in a single-step process.
  
  
  RESULTS
  The reaction sequences were carried out in an open-air reactor with free and immobilised lipases (triacylglycerol acylhydrolases, E.C. 3.1.1.3): Candida rugosa lipase to obtain polyricinoleic acid and Rhizopus oryzae lipase for the esterification of polyglycerol with the carboxyl group of ricinoleic or polyricinoleic acid. A co-immobilised derivative containing both lipases was used to catalyse the single-stage scheme. The three processes were carried out in a vacuum reactor, obtaining in every case PGPR that complied with the legal specifications of the European Community and recommendations provided in the Food Chemical Codex.
  
  
  CONCLUSIONS
  The results demonstrate that all three protocols are viable for the enzymatic synthesis of PGPR and require similar reaction times. The single-stage scheme is easier to carry out.
authors.affiliation: Department of Chemical Engineering, University of Murcia, Campus de Espinardo, 30071, Murcia, Spain.
authors.forename: Salvadora
authors.initials: S
authors.lastname: Ortega-Requena
authors.forename: José L
authors.initials: JL
authors.lastname: Gómez
authors.forename: Josefa
authors.initials: J
authors.lastname: Bastida
authors.forename: Fuensanta
authors.initials: F
authors.lastname: Máximo
authors.forename: María C
authors.initials: MC
authors.lastname: Montiel
authors.forename: María D
authors.initials: MD
authors.lastname: Murcia
mesh_terms: D055162:Biocatalysis; D002175:Candida / Q000201:enzymology*; D004800:Enzymes, Immobilized / Q000378:metabolism*; D004951:Esterification; D004952:Esters; D005990:Glycerol / Q000031:analogs & derivatives* / Q000378:metabolism; D008049:Lipase / Q000378:metabolism*; D011108:Polymers / Q000378:metabolism*; D012233:Rhizopus / Q000201:enzymology*; D012277:Ricinoleic Acids / Q000378:metabolism*
chemical_list: D004800:Enzymes, Immobilized; D004952:Esters; D011108:Polymers; D012277:Ricinoleic Acids; C029243:glyceran polyricinoleic acid ester; C043941:polyglycerol; D008049:Lipase; C030521:ricinoleic acid; D005990:Glycerol
keywords: Candida rugosa lipase; Rhizopus oryzae lipase; biocatalysis; enzyme immobilisation; fatty acid esters; process optimisation