Acylglycerol synthesis including EPA and DHA from rainbow trout (Oncorhynchus mykiss) belly flap oil and caprylic acid catalyzed by Thermomyces lanuginosus lipase under supercritical carbon dioxide

Abstract

Supercritical carbon dioxide (SCCO2) was studied as a medium for the esterification of eicosapentaenoic acid (n-3 C20:5, EPA) or docosahexaenoic acid (n-3 C22:6, DHA) and caprylic acid (C8:0, CA) in structured triacylglycerols (sTAG) using Thermomyces lanuginosus lipase as biocatalyst. Process variables (n-3 long-chain polyunsaturated fatty acid: CA, n-3 LCPUFA:CA content ratio), glycerol content (wt. %), and supercritical time, temperature and pressure were optimized by the Response Surface Methodology through a central composite design of 25–1 + star. Synthesis of sTAG with EPA, DHA and CA under SCCO2 was significantly affected by the n-3 LCPUFA:CA content ratio and supercritical time. MALDI-TOF mass spectrometry revealed that acylglycerols with the highest levels of EPA or DHA content in the sn-2 position were obtained when the following variables conditions were applied: 50% (n-3 LCPUFA:CA content ratio), 40 °C (supercritical temperature), 20 MPa (supercritical pressure), 4 h (supercritical time) and 20.0 wt. % (glycerol concentration). For such experimental conditions, esterification catalyzed by Thermomyces lanuginosus lipase under supercritical carbon dioxide allowed obtaining sTAG synthesized with 54.95% of CA, 11.64% of EPA and 13.77% of DHA.