Lipase immobilization on activated and functionalized carbon for the aroma ester synthesis

Abstract

This study aimed to investigate the effect of functionalized activated carbon (AC) on lipase immobilization and to use the biocatalysts obtained in the synthesis of isoamyl acetate ester (banana odor). Pupunha palm sheaths were used as a precursor material in the synthesis of activated carbon, which was functionalized by the glutaraldehyde method. The effect of the medium pH and temperature on the lipase immobilization capacity in the different matrices was evaluated, as well as the hydrolytic activity of the derivatives obtained. The AC showed 1260 m2 g−1 surface area and average pore diameter accessible to the enzyme (6.60 nm). The functionalization provided a modification of the matrix surface by the insertion of amine-aldehyde groups and a reduction in porosity and surface area (340 m2 g−1) when compared to AC. The enzyme immobilized on both supports showed specific activity greater than 0.450 U/mg in the best immobilization conditions (pH 5.0 and 30 °C). The immobilized enzyme was used in the esterification reaction, using acetic acid and isoamyl alcohol as a substrate, reaching conversions around 93% and 91% for the enzyme immobilized in the activated and functionalized carbons, respectively, for a reaction time of 180 min. Operational stability showed promising results for both biocatalysts, with no significant reduction in the catalytic activity for ester synthesis during the 5 cycles of reuse studied.