Qiao Dongling, Lu Jieyi, Shi Wenjuan, Li Hao, Zhang Liang, Jiang Fatang, Zhang Binjia
Glyn O. Phillips Hydrocolloid Research Centre at HBUT, National "111" Center for Cellular Regulation and Molecular Pharmaceutics, School of Food and Biological Engineering, Hubei University of Technology, Wuhan 430068, China.
School of Food Science and Engineering, Yangzhou University, Yangzhou 225127, China.
Carbohydr Polym. 2022 Jan 15;276:118776. doi: 10.1016/j.carbpol.2021.118776. Epub 2021 Oct 18.
From a microstructural point of view, this work concerns how deacetylation improves the practical characteristics of deacetylated-konjac glucomannan/agar (DK/A) composite films. As disclosed by infrared spectroscopy and X-ray diffraction, the deacetylation of konjac glucomannan (KGM) enhanced the chain interactions in DK/A composites and suppressed the realignment of agar molecules into crystallites. The enhanced associations between acetyl-free regions of KGM and agar reduced the exposure of OH groups and thus increased the hydrophobicity of the composites. Besides, the partial removal of acetyl groups allowed shortened distances between chains; consequently, denser composite matrices emerged with lower water vapor permeability and higher tensile strength. Also, the KGM deacetylation increased the matrix flexibility and elongation at break for DK/A composites, associated with the hindered rearrangement of agar chains. Thus, altering the deacetylation degree of KGM may be an effective way to design KGM-based composites with improved hydrophobicity and mechanical performance.
从微观结构的角度来看，这项工作关注的是脱乙酰作用如何改善脱乙酰化魔芋葡甘聚糖/琼脂（DK/A）复合膜的实际特性。如红外光谱和X射线衍射所示，魔芋葡甘聚糖（KGM）的脱乙酰作用增强了DK/A复合材料中的链间相互作用，并抑制了琼脂分子重排成微晶。KGM无乙酰基区域与琼脂之间增强的缔合减少了OH基团的暴露，从而增加了复合材料的疏水性。此外，部分乙酰基的去除使链间距离缩短；因此，出现了更致密的复合基质，其具有更低的水蒸气透过率和更高的拉伸强度。而且，KGM的脱乙酰作用增加了DK/A复合材料的基质柔韧性和断裂伸长率，这与琼脂链重排受阻有关。因此，改变KGM的脱乙酰度可能是设计具有改善的疏水性和机械性能的KGM基复合材料的有效方法。
