Enzymatic synthesis of cosmetic grade wax ester in solvent free system: optimization, kinetic and thermodynamic studies

Abstract

The enzymatic synthesis of cetyl caprate, a cosmetic grade ester was studied by esterification of cetyl alcohol and capric acid using Fermase CALB™10000 under solvent free condition. The process parameters namely, temperature, enzyme loading, molar ratio, agitation speed have been investigated and optimized to attain maximum yield of cetyl caprate. The maximum yield of 91.9% was obtained in 80 min under optimized conditions of 50 °C temperature, 3% enzyme loading, capric acid:cetyl alcohol ratio of 1:3, and 200 rpm stirring speed. The enzyme operational stability study reveals that enzyme can retain its original activity for the synthesis of cetyl caprate and could be reused up to five to six times without any notable loss of catalytic activity. The kinetics of the reaction was derived by employing non-linear regression consideration, and the experimental results and kinetic evaluation showed that reaction obeys ping-pong bi–bi model. The kinetic parameters, Vmax = 21.886 M/min/g catalyst, KA = 1.194 × 10−2 M, KB = 8.4512 M, KiA = 2.02 × 10−2 M, KiB = 3.55 × 10−4 M and SSE = 4.31 × 10−5 measured from initial rate data were used to replicate experimental results with good agreement. The thermodynamic parameters, i.e., change in enthalpy, Gibb’s free energy, change in entropy was evaluated at different operating temperatures. Thus, current research work strikes a significant imprint in the cosmetic industry by synthesizing green and natural product using biocatalysis under solvent free condition.