Deacetylation enhances the properties of konjac glucomannan/agar composites

Dongling Qiao; Jieyi Lu; Wenjuan Shi; Hao Li; Liang Zhang; Fatang Jiang; Binjia Zhang

doi:10.1016/j.carbpol.2021.118776

Deacetylation enhances the properties of konjac glucomannan/agar composites

Carbohydr Polym. 2022 Jan 15:276:118776. doi: 10.1016/j.carbpol.2021.118776. Epub 2021 Oct 18.

Authors

Dongling Qiao¹, Jieyi Lu¹, Wenjuan Shi¹, Hao Li¹, Liang Zhang², Fatang Jiang¹, Binjia Zhang³

Affiliations

¹ 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.
² School of Food Science and Engineering, Yangzhou University, Yangzhou 225127, China.
³ Group for Cereals and Oils Processing, College of Food Science and Technology, Huazhong Agricultural University, Wuhan 430070, China. Electronic address: zhangbj@mail.hzau.edu.cn.

PMID: 34823792
DOI: 10.1016/j.carbpol.2021.118776

Abstract

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.

Keywords: Agar; Deacetylated-konjac glucomannan; Hydrophobicity; Mechanical properties.