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 2(5-1) + 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 degrees 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.