FISH OIL ETHANOLYSIS BY LIPOZYME RM IM IN SUPERCRITICAL CO2

RODRIGO MELGOSA , M. TERESA SANZ, ÁNGELA G. SOLAESA , ALMUDENA V. MERCHÁN , SAGRARIO BELTRÀN; DANIELA LAMAS

Cádiz

Encuentro; VIII Reunión de Expertos en Fluidos Comprimidos; 2015

FLUCOMP Asociación de Expertos en Fluidos Comprimidos

The implications of omega-3 polyunsatturated fatty acids (n-3 PUFAs) in human health have been the subject of an enormous number of epidemiological and clinical studies, scientific articles and reviews in the last years. A brief summary can be found in the work by Rubio-Rodríguez et al. (2010). Their beneficial effects have drawn the attention of the pharmaceutical and food industry and there are numerous examples of the use of n-3 PUFAs as active compounds in pharmacology or functional ingredients in food products.  Fish oil is anatural source of n-3 PUFAs, especially eicosapentaenoic acid (EPA, 20:5 n-3)and docosahexaenoic acid (DHA, 22:6 n-3). However, previous modification and concentration steps are required in order to obtain concentrates of n-3 PUFAsin a chemical form with good bioavailability and stability against oxidation. Traditional and novel methods to obtain these fish oil derivatives have been reviewed by Rubio-Rodríguez et al. (2010), including enzymatic methods using supercritical fluids as reaction media. In this work, ethanolysis of a mixture of tuna and sardine oil catalysed by a comercial immobilized lipase, Lipozyme RM IM from Rhizomucor miehei (Novozymes), was performedin supercritical carbon dioxide (SC-CO2) Results obtained showed a positive effect of the initial substrate molar ethanol:fishoil ratio (from 2:1 to 6:1) on the total conversion and the initial reaction rate. Above this point, higher amounts of ethanol possibly caused enzyme inhibition. Different temperature and pressure combinations were also assayed at a fixed initial substrate molar ratio of 6:1. In the range investigated, a maximum in total conversion and initial reaction rate was found at 65ºC and 10MPa, possibly because of the physical properties of the solvent, which may be favourable due to lower mass transfer limitations under such conditions (Knez2009). Above this optimal temperature, lower conversion due to thermaldeactivation of the catalyst was observed. Increasing pressure from 7.5 to 10MPa at 50ºC led to a sharp increase in total conversion and initial reactionrate, whereas further pressure increment showed a gradual decay in both parameters.The solvation of SC-CO as reaction medium. The reaction was performed in ahigh-pressure batch-stirred tank reactor with an internal volume of 100 mL.Samples were taken periodically during 24 h from the bottom of the reactorthrough a siphoned capillary. Temperatures and pressures investigated ranged between 50-80 ºC and 7.5-20 MPa. Initial substrate molar ratio has been varied from 2:1to 38:1 (ethanol:fish oil). Enzyme loading was fixed at 5% wt. of substrates.The neutral lipid profile of each sample was determined by High Performance Liquid Chromatography (HPLC). Ethanol and glycerol were analysed by HighTemperature Gas Chromatography (HT-GC), using triethylenglycol as internal standard.2 in the liquid phase, which initially expands the mixture improving mass transfer properties, may decelerate the reaction due to dilution effects at higherpressures (Laudani et al. 2007).