Heterogeneous interesterification of triacylglycerols catalyzed by using potassium-doped alumina as a solid catalyst

Heterogeneous interesterification of vegetable oils offers an environmentally more attractive option for the modification of edible oils to meet the specifications for certain food applications. In this work, potassium-doped alumina (KNO3/Al2O3) was prepared using an impregnation method, followed by calcinations at a temperature of 700 °C, and was then employed as heterogeneous catalysts for the interesterification of triacylglycerols. The solid catalyst was characterized by means of Hammett titration method, power X-ray diffraction, scanning electron microscopy, and nitrogen adsorption-desorption techniques. It was determined that the catalyst with KNO3 loading of 35% on alumina support and calcined at 700 °C exhibited the best catalytic activities toward the interesterification between soybean oil and methyl stearate under solvent-free conditions. Also, the solid base catalyst was successfully applied to the interesterification of soybean oil and lard blends in a heterogeneous manner. The physicochemical properties of the interesterified products were investigated using gas chromatography, high-performance liquid chromatography, and confocal laser scanning microscopy. It was found that the slip melting point and crystal morphology had a significant variation after the interesterification reaction as a result of the modification in the TAG profile. With the solid base catalyst, an environmentally friendly approach for the interesterification of triacylglycerols in a heterogeneous manner was developed.