| Medium chain diacylglycerols (MCD) and medium- and long-chain diacylglycerols (MLCD) were prepared via the enzymatic esterification of molecular distillated monoacylglycerols (MAG) rich in palmitic acid and stearic acid and capric acid catalyzed by Novozyme 435. The effects of substrate molar ratio, reaction temperature, reaction time and enzyme dosage on the content of DAG in the product were studied by single factor experiment, and the obtained DAG were charact erized by differential scanning calorimeter (DSC), pulsed nuclear magnetic resonance (p-NMR), X-ray diffractometer (XRD) and polarized light microscope (PLM) to study its compositions of fatty acids and glyceride, thermodynamics properties, solid fat content and crystallization property. The results showed that the optimal conditions were obtained as follows: molar ratio of capric acid to MAG 1∶?1, enzyme dosage 5%, reaction temperature 65?℃ and reaction time 35 min. Under these conditions, the content of DAG was (37.3±0.1)%, which consisted of (7.28±0.1)% of MCD and (3002±0.1)% of MLCD, and the content ratio of DAG to TAG was 9.8∶?1 in the crude products. Solid fat content profiles demonstrated that the products had potential use in plastic fats after purification. XRD spectra reflected that β form was the dominant crystal form in the final system. The results could provide theoretical basis for the development of further products. |
