Kinetics of enzymatic esterification of oleic acid and decanol for wax ester and evaluation of its physico-chemical properties

• It is a comprehensive work on enzymatic synthesis kinetics of decyl oleate.
• Development of kinetics for enzymatic esterification of oleic acid and decanol.
• Physico-chemical properties of the product such as acid value, refractive index, density, contact angle, surface tension etc. were evaluated.

Decyl oleate is an important skin conditioning agent derived from the esterification of oleic acid and decanol. It is widely used in many cosmetic products as it has a composition similar to that of natural skin lipids. This study presents the kinetics of wax ester synthesis from oleic acid and decanol in the presence of Novozym 435 enzyme. The effects of various parameters such as reaction time, enzyme concentration, reaction temperature, and oleic acid–decanol mole ratio were investigated. The optimal conditions were found to be 1:1 oleic acid–decanol mole ratio, 2.5% enzyme concentration, 45 °C temperature and 60 min reaction time. A second order reversible reaction kinetic model was proposed to describe this reaction and a good agreement was observed between the experimental data and the model values. The effect of temperature on the forward reaction rate constant and equilibrium constant were determined by fitting them to the Arrhenius and van't Hoff equations respectively. The activation energy for forward reaction and the heat of reaction were found to be 16.24 kcal/mol and 16.63 kcal/mol respectively. The physico-chemical properties of the product were also evaluated and compared with jojoba oil.

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