Enzymatic synthesis of oleamide using lipase immobilized in chitosan

Abstract

Oleamide is an alkylamide (fatty acid amide) that is synthesized from oleic acid and urea enzymatically using Candida rugosa lipase. The lipase is immobilized by entrapping method with chitosan matrix. One of the functions of oleamide is a surfactant. This study aimed to determine the optimum conditions for oleamide synthesis with reaction time and mole ratio parameters. Oleamide was synthesized from oleic acid with urea and was carried out by varying the reaction time at 6, 12, 24, 36, 48 hours and the mole ratio between oleic acid and urea at (1:1, 1:2, 1:3, 1:4, 1:5) with dichloromethane as solvent. The optimum conditions are indicated based on the highest conversion percentage that was calculated by the moles number of reacted oleic acid divided by the moles number of initial oleic acid. The oleic acid concentration was determined by alkali metric titration. The data of conversion percentage were statistically analyzed by one-way ANOVA followed by Tukey test. The resulting oleamide was identified using FTIR spectrophotometer and measured its HLB value. The result showed that reaction time and mole ratio had a significant effect on oleamide synthesis. The optimum conditions for oleamide synthesis occurred at 36 hours reaction time, and the moles ratio (1:5) resulted in 31.42±0.54% of the highest conversion percentage. Oleamide has been identified and characterized by FTIR spectrophotometer which showed absorption at wavenumbers 3226.09-3377.27 cm−1 (N-H), 2855.28-2926.59 cm−1 (C-H), 1655.83 cm−1 (C=O), and 1163.79 cm−1 (C-N). Oleamide has an HLB value of 5.64, which belong to a W/O emulsifier.