title: Preparation of triacylglycerols rich in omega-3 fatty acids from sardine oil using a Rhizomucor miehei lipase: focus in the EPA/DHA ratio.
abstract: The increasing evidence on the differential biochemical effects of eicosapentaenoic acid (EPA)/docosahexaenoic acid (DHA) raises the need of n-3 highly unsaturated fatty acid concentrates with different amounts of these fatty acids. In the present work, physicochemical and enzymatic techniques were combined to obtain acylglycerols, mainly triacylglycerols (TAG), rich in n-3 fatty acids. Sardine oil was obtained by washing sardine (Sardina pilchardus) mince with a NaHCO3 solution, hydrolyzed in a KOH-ethanol solution, and concentrated with urea. The esterification reaction was performed in the stoichiometric proportion of substrates for re-esterification to TAG, with 10 % level of Rhizomucor miehei lipase based on the weight of substrates, without any solvent, during 48 h. This procedure led to approximately 88 % of acylglycerols, where more than 66 % were TAG and the concentration of n-3 fatty acids was higher than 60 %, the EPA and DHA ratio (EPA/DHA) was 4:1. The content of DHA in the unesterifed fraction (free fatty acids) increased from 20 to 54 %, while the EPA level in the same fraction decreased from 33 to 12.5 % (EPA/DHA ratio ≈1:4). Computational methods (density functional theory calculations) have been carried out at the B3LYP/6-31G(d,p) level to explain some of the experimental results.
authors.affiliation: Department of Biochemistry and CEDOC, Faculty of Medical Sciences, Universidade Nova de Lisboa (UNL), Campo Mártires da Pátria, 130, 1169-056, Lisbon, Portugal, pauloffbispo@gmail.com.
authors.forename: Paulo
authors.initials: P
authors.lastname: Bispo
authors.forename: Irineu
authors.initials: I
authors.lastname: Batista
authors.forename: Raul J
authors.initials: RJ
authors.lastname: Bernardino
authors.forename: Narcisa Maria
authors.initials: NM
authors.lastname: Bandarra
mesh_terms: D004281:Docosahexaenoic Acids / Q000737:chemistry* / Q000378:metabolism; D015118:Eicosapentaenoic Acid / Q000737:chemistry* / Q000378:metabolism; D015525:Fatty Acids, Omega-3 / Q000737:chemistry*; D005395:Fish Oils / Q000737:chemistry*; D005656:Fungal Proteins / Q000378:metabolism; D008049:Lipase / Q000378:metabolism*; D020103:Rhizomucor / Q000201:enzymology*; D014280:Triglycerides
chemical_list: D015525:Fatty Acids, Omega-3; D005395:Fish Oils; D005656:Fungal Proteins; D014280:Triglycerides; D004281:Docosahexaenoic Acids; D015118:Eicosapentaenoic Acid; D008049:Lipase