Kinetic modeling of hydrolysis of canola oil in supercritical media

The industrial production of free fatty acids (FFA) by oil hydrolysis could benefit from the properties of supercritical carbon dioxide (SC-CO2). Indeed, SC-CO2 is an excellent reaction medium and its use simplifies the separation of the FFA from the product mixture. Although the benefits of SC-CO2 are known, it is not currently used commercially, in part due to the lack of reaction kinetics information. Therefore, the objective of this study was to investigate the kinetics of canola oil hydrolysis in SC-CO2 media. Reactions in SC-CO2 were conducted at 250 °C, 10–30 MPa, and using 1:3, 1:17 and 1:70 canola oil to water initial molar ratio (o/w). Reactions were also conducted in supercritical nitrogen at 10 MPa, 250 °C and 1:17 o/w. Samples were collected as a function of time and monoacylglycerol, diacylglycerol, triacylglycerol and FFA concentrations were determined. Rate constants were obtained by kinetic modeling of the data. The maximum rate of FFA production (FFAmax) was not affected (p > 0.05) by supercritical media or pressure but it was delayed at 30 MPa. FFAmax increased significantly (p < 0.05) as the amount of water was increased from 1:3 to 1:17 and 1:70 o/w. Using the calculated rate constants, the mechanism of the hydrolysis of canola oil was determined. The findings provide valuable information for optimization of industrial hydrolysis.