Diacylglycerols have been extensively
used in food, medicine, cosmetic,
and pharmaceutical industries due to their outstanding properties
as emulsifiers and stabilizers as well as their nutritional benefits
to humans. This study investigated the optimization and kinetics of
lipase-catalyzed synthesis of glycerol dioleates (GDO) through esterification
of glycerol with oleic acid in a mixed solvent system of acetone/tert-butanol. Process variables, namely, solvent ratio,
temperature, and enzyme loading, were optimized to acquire maximum
conversion and selectivity. A high oleic acid conversion of 73% and
GDO selectivity of 77% were obtained in an acetone/tert-butanol 70:30 (v/v) mixture at 45 °C and an enzyme load of
0.15 g. The bi substrates Ping-Pong Bi-Bi kinetic model was employed
for initial rate determination, which was fitted to the experimental
results. At an applied temperature of 45 °C, the Ping-Pong Bi-Bi
model with no substrate inhibition gives the best fit with parameter
values of V
max = 1.21 M h–1, K
m
[G] = 1.81 M, and K
m
[OA] = 6.81 M for glycerol and oleic acid concentrations between 0.31
to 1.32 M and 1.88 to 2.13 M, respectively.