Three phenolic acids including p -hydroxybenzoic acid (PHBA), 3,4-dihydroxybenzoic acid, (DHBA), and gallic acid (GA) were grafted onto native pectin (Na-Pe) through enzymatic method . Ultraviolet–visible spectrometry, Fourier transform infrared spectroscopy , and 1 H NMR analyses were used to explore the reaction mechanism. Results indicated that the p -hydroxyl of the phenolic acids reacted with the methoxycarbonyl of pectin through transesterification , and a covalent connection was formed. The phenolic acid contents of PHBA modified pectin (Ph-Pe), DHBA modified pectin (Dh-Pe), and GA modified pectin (Ga-Pe) were 20.18%, 18.87%, and 20.32%, respectively. After acylation with phenolic acids, the 1,1-diphenyl-2-picryl hydrazine clearance of pectin changed from 7.68% (Na-Pe) to 6.88% (Ph-Pe), 40.80% (Dh-Pe), and 90.30% (Ga-Pe), whereas its inhibition ratio of pectin increased from 3.11% (Na-Pe) to 35.02% (Ph-Pe), 66.36% (Dh-Pe), and 77.89% (Ga-Pe). Moreover, compared with Na-Pe, modified pectins exhibited better emulsification properties and stronger antibacterial activities against both Escherichia coli and Staphylococcus aureus .
Wang Jianye,Liu Haifeng,Chen Zhonghui,Sun Yifeng,Wang Song
Waste crayfish shell powder was utilized to prepare a series of solid base catalyst for the transesterification of glycerol with dimethyl carbonate to synthesize glycerol carbonate. Thermal decomposition behavior of waste crayfish shell powder was investigated by thermogravimetric analysis (TGA) and the different catalysts prepared at different calcinations temperature were characterized using FESEM, XRD, FTIR, BET techniques. It was clearly confirmed that the catalyst generated by the calcination of waste crayfish shell at 800 °C exhibited excellent catalytic activity, 98.7% glycerol conversion and 95.3% glycerol carbonate yield were obtained under mild reaction conditions such as 90 min of reaction time, 1:6 molar ratio of glycerol to dimethyl carbonate, 4 wt% of catalyst loading and 75 °C of reaction temperature.
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