This paper, written by researchers from Northeast Agricultural University and others, discusses Ultrasonic pretreatment promotes diacylglycerol production from lard by lipase-catalysed glycerolysis and its physicochemical properties. The paper is published in an important journal < Ultrasonics Sonochemistry >. IF：6.012.

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The objective of this study was to evaluate the effect of ultrasonic pretreatment on diacylglycerol (DAG) synthesis by lipase-catalysed glycerolysis of lard and to analyse the physicochemical properties of lard-based DAG. The optimal ultrasonic pretreatment conditions were: Rhizomucor miehei (Lipozyme® RMIM)-to-lard ratio 4:100 (W/W), 45 °C for 5 min, and power 250 W. The lard-based DAG samples for 4 h of glycerolysis reactions with ultrasonic pretreatment (named DAG-U) and 11 h of glycerolysis reactions without ultrasonic pretreatment (named DAG-N) had similar DAG contents and were used for further analysis. The major FA compositions and iodine value of lard, DAG-U and DAG-N were similar. Fourier transform infrared spectroscopy analysis proved that enzymatic glycerolysis with and without ultrasonic pretreatment did not change the structure of the lard. Differential scanning calorimetry analysis showed that the crystallization onset of DAG-U and DAG-N shifted to higher temperatures than that of lard, which indicated that DAG oils accelerated nucleation and crystal growth. X-ray diffraction analysis revealed that both DAG-U and DAG-N contained β′ crystal and a substantially lower amount of β crystal. Overall, ultrasonic pretreatment promotes diacylglycerol production from lard through lipase-catalysed glycerolysis, and DAG-U and DAG-N have similar physicochemical properties.

In this study, DAG production via lipase-catalysed glycerolysis of lard with and without ultrasonication was investigated, and the physicochemical properties of DAG were studied. At the optimized ultrasonic pretreatment conditions, TAG conversion and the DAG content of lipase-catalysed glycerolysis were 76.68% and 46.91%, respectively. The ultrasonic pretreatment significantly shortened the glycerolysis reaction time. The DAG content of 4 h of glycerolysis reactions with ultrasonic pretreatment was similar to the 11 h of glycerolysis reactions without ultrasonic pretreatment. No remarkable variations were observed between DAG-U and DAG-N in the FA compositions, iodine value, FTIR spectra, thermal properties, and crystal form, while the physicochemical properties of lard-based DAG differed somewhat from lard. The difference between the physicochemical properties of DAG oils and lard can likely be attributed to differences in their chemical compositions and structures. These results revealed that ultrasound pretreatment was very effective in promoting the synthesis of lardbased DAG, and DAGs produced with and without ultrasound pretreatment had similar physicochemical properties.

Ultrasonic pretreatment was performed in a XH-2008D ultrasonic instrument (Xianghu development Co., Ltd., Beijing, China) equipped with a reactor with a thermostatic water bath (temperature accuracy of±1 °C), a mechanical stirrer and a microtip probe (diameter of 8 mm) connected to a sonotrode. The operating frequency of the ultrasonic equipment was 25 kHz, and the power was 100–1500 W.