Enzymatic preparation of castor oil-based feruloylated lipids using ionic liquids as reaction medium and kinetic model

• Reaction showed high selectivity (0.68 ± 0.01) for FMAGs + FDAGs formation in EMIMPF6.
• A protection against the thermal inactivation of Novozym 435 was found in EMIMPF6.
• The activation energy for the transesterification in EMIMPF6 was 64.37 ± 3.00 kJ/mol.
• The reaction agreed with Ping-Pong Bi-Bi mechanism without substrates inhibition.

The aim of the work was to investigate the effect of ionic liquids (ILs) on the enzymatic transesterification of ethyl ferulate (EF) with castor oil. Effects of ethanol removal, enzyme concentration, reaction temperature, and substrate molar ratio on the transesterification and castor oil-based feruloylated lipids preparation were also studied. Of three kinds of imidazolium ILs (BF4—, PF6— and TF2N—), EMIMPF6 exhibited the highest EF conversion (∼100%) and showed an excellent reaction selectivity for lipophilic castor oil-based feruloylated mono- and di-acylglycerols (FMAGs and FDAGs) formation. And a significant protective effect against thermal inactivation of the enzyme was found in EMIMPF6. The Arrhenius equation was ln v0 = 13.17–64.37/RT, and Ea (activation energy) was 64.37 ± 3.00 kJ/mol. The transesterification kinetic agreed with the Ping-Pong Bi-Bi mechanism without substrate inhibition.

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