Performance of two immobilized lipases for interesterification between canola oil and fully-hydrogenated canola oil under supercritical carbon dioxide

•Successful use of Lipozyme TL IM and RM IM for lipid interesterification in SCCO2.•No effect on degree of interesterification after SCCO2-treatment of immobilized enzymes.•No significant effect on morphology of immobilized enzymes by exposure to SCCO2.•Decrease of reaction intermediates when SCCO2-treated enzymes used for interesterification.•Acceptable reusability of enzymes for interesterification under SCCO2.

The performance and stability of Lipozyme RM IM and TL IM for the interesterification between canola oil and fully-hydrogenated canola oil (FHCO) in the presence of SCCO2 were studied using a high pressure batch stirred reactor at 65 °C/17.5 MPa. The influence of exposure time (4, 8, and 12 h) in SCCO2 and pressurization/depressurization cycles of up to 12 times on the enzyme's resultant activity were studied. There was no significant difference (p > 0.05) in the performance of the two enzymes over reaction time, reaching a constant degree of interesterification of about 23% after 2 h. Although FE-SEM images illustrated some morphological changes on the surface of the enzymes after 4 cycles of 7 h each, similar degrees of interesterification were achieved after each cycle. However, the amount of reaction intermediates decreased by 50-60% in the product obtained by using SCCO2-treated enzymes after 12 pressurization/depressurization cycles compared to untreated enzymes, while there were no significant changes in the conformational and morphological structure of the treated enzymes based on FTIR and FE-SEM analysis. Findings enhance our understanding of enzymatic conversions of lipids under high pressure CO2, targeting production of base-stock for zero-trans margarines.