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Stearic acid esterified pectin: Preparation, characterization, and application in edible hydrophobic pectin/chitosan
Pengkai Wang1, Peng Fei2, Chunxia Zhou1
1College of Food Science and Technology, Guangdong Ocean University, Guangdong Provincial Key Laboratory of Aquatic Product Processing and Safety, Guangdong Provincial Engineering Technology Research Center of Marine Food, Guangdong Provincial Modern Agricultural Science and Technology Innovation Center, Zhanjiang 524088, China; Southern Marine Science and Engineering Guangdong Laboratory (Zhanjiang), Zhanjiang 524025, China.
Abstract:
This work investigated the modification of low-methoxy pectin with stearic anhydride through microwave action with 4-dimethylaminopyridine as catalyst. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analyses indicated that stearic acid was grafted on the pectin through esterification reaction, with the maximum stearic acid grafting ratio (SGR) of 10.7% for the modified pectin. The introduction of stearic acid was shown to significantly improve the emulsifying activity and stability of pectin. Composite films were prepared by blending the modified pectins and chitosan, and compared with the contact angle of 65.3° for the film with native low-methoxy pectin (PC0), the films with modified pectins showed a significant angle increase, with the highest contact angle reaching 101.9°, indicating a hydrophobic surface. Moreover, an appropriate amount of aliphatic chains could improve the tensile strength and elongation at break of the composite films due to the "anchoring effect".
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