HYBRID EVENT: You can participate in person at Valencia, Spain or Virtually from your home or work.
Cristina Paul, Speaker at Green Chemistry Conferences
Politehnica University Timisoara, Romania
Title : Optimized continuous-flow aroma ester synthesis by entrapped Candida antarctica lipase B in novel sol-gels with epoxy functional groups


Immobilized lipases are excellent biocatalysts for the enzymatic synthesis of short- and medium-chain fatty esters used as food flavour compounds. However, because its catalytic activity greatly depends on the selected immobilization method, it is necessary to customize the immobilization procedure to the selected enzyme and the envisioned applications.

Lipase from Candida antarctica B (GenoFocus, South Korea) was immobilized by entrapment in sol-gel hybrid matrices obtained with epoxy functionalized silane precursors following the hypothesis that the epoxide groups could lead to formation of supplementary covalent bonds between the enzyme and the sol-gel matrix, thus serving to further stabilize the enzyme.

The characterization of the immobilized biocatalyst was accomplished through Scanning Electron Microscopy (SEM), Fluorescence Microscopy (FM), Fourier Transform Infrared Spectroscopy (FTIR), and Thermogravimetric Analysis (TG/DTA). The operational and thermal stability of the lipase were increased as a result of the immobilization, and the entrapped lipase retained 99% activity after 10 consecutive reaction cycles.

The catalytic efficiency of the immobilized lipase was investigated in the synthesis of the flavour ester n-amyl hexanoate (apple, pineapple aroma) in organic solvent/solvent free media, by direct esterification of n-amyl alcohol and hexanoic acid. Continuous production of the flavour ester pentyl hexanoate in a packed-bed reactor was first developed using the immobilized lipase as a catalyst in a hexane solvent system. Subsequently, a solvent-free synthesis process was developed and optimized. This study demonstrates the applicability of sol-gel entrapped lipases in a packed-bed reactor for continuous aroma ester synthesis.

Audience take away

  • Enzyme immobilization through the sol-gel entrapment method
  • Biocatalyst characterization and correlation of its properties with catalytic activity
  • Process optimization by design of experiments
  • Continuous flow ester synthesis in solvent-free media


Dr. Eng. Cristina Paul studied Industrial Chemistry and Environmental Engineering at the University Politehnica Timisoara, Romania. In 2004 she joined the biocatalysis research group of Prof. Francisc Péter at University Politehnica Timisoara, Faculty of Industrial Chemistry and Environmental Engineering. Graduated from the Politehnica University Timisoara with an MS in Fine Organic Synthesis, Semisynthesis and Natural Products in 2005 and received her PhD in Chemistry in 2009 at the same institution. Her research interests include: biocatalysis, biotransformation, biomaterials, enzyme immobilization, sol-gel entrapment, green chemistry, enzymatic conversion of lignocellulosic biomass, nanomaterials, magnetic nanoparticles, process optimization, experimental design.