Physicochemical and rheological properties of konjac glucomannan and its mixed gels with κ-carrageenan: Effect of deacetylation by L-arginine

Abstract

Konjac glucomannan (KGM) is a natural functional polysaccharide, and deacetylation (removing acetyl groups) impacts its physicochemical and gel properties. In order to study KGM's gel properties and explore new deacetylation modifiers, three deacetylated konjac glucomannan (DKGM) with different deacetylation degrees (DD, 17.51 %, 35.41 %, and 54.52 %) were prepared using L-arginine. Results showed that L-arginine deacetylated and retained the main structure and high molecular weight of KGM. Solubility decreased from 85.38 % to 81.17 %, transparency decreased from 38.52 % to 35.73 %, water absorbing and swelling slowed down, and molecular morphology changed from chain structures to micelle-like aggregates after deacetylation. Dynamic viscoelastic analysis showed that deacetylation facilitated the formation of the entangled network structure of KGM. The strength of konjac glucomannan and κ-carrageenan mixed gels increased after deacetylation, and this enhancement was mainly through hydrogen bonds and hydrophobic interactions. These findings will provide theoretical guidance for the application of KGM.

Keywords: Deacetylation; Konjac glucomannan; Mixed gel; Κ-Carrageenan.