Physicochemical properties of lard-based diacylglycerols in blends with lard

The objective of the study was to investigate how blending of triacylglycerols and diacylglycerols affected the melting and crystallisation properties in a solid fat system. Lard-based diacylglycerols (DAGs) were blended with lard in various concentrations (0%, 1%, 5%, 10%, 20%, 50%, 60%, 70%, 80%, 90%, and 100%). The melting and crystallisation properties were investigated by the determination of dropping point (DP), solid fat content (SFC), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). In general, the effects of DAGs were found to be dependent on concentration. The DP was significantly (P<0.0001) decreased when DAGs were added to the lard from 5-50%, whereas the DP was increased (P<0.0001) when the blends contained more than 60% DAGs. The DSC thermograms showed that DAGs changed the melting and crystallisation profiles of lard. The crystallisation onset point increased (P<0.05) with increasing the DAG concentrations (10-100%). The melting peaks and off-set points generally shifted slightly towards higher temperatures as the content of DAGs increased above 50%. DAG content of 5% and 10% resulted in lowering of the off-set point. The lard contained both β and β' crystals. The β form was more pronounced in the blends with high concentrations of DAGs. Blending of TAGs and DAGs may serve as a solution to achieve specific functional properties in products containing solid fats.