Complex coacervation of carboxymethyl konjac glucomannan and chitosan and coacervate characterization

Abstract

Carboxymethyl konjac glucomannan (CMKGM) shows potential in the construction of colon-targeted delivery systems through electrostatic interaction-based techniques. Its coacervation with chitosan (CHI) was investigated as a function of degree of substitution (DS). CMKGMs displayed the same optimum coacervation conditions of pH 6.5 and mass ratio 1:1 with CHI, but the coacervate yield was positively related to their DS. The coacervation was weakened by the presence of NaCl, but was not affected in temperatures 25–75 °C and total biopolymer concentrations 0.05–0.15% (w/v). Both electrostatic interaction and hydrogen bonding were involved in the coacervation and a higher DS contributed a denser network structure, a smaller particle size, and greater elasticity. The coacervates maintained their structures in simulated gastrointestinal fluids, but could be degraded by the β-mannanase in simulated colonic fluid. Hence, CMKGMs could be used in colon-targeted and enzyme-triggered delivery systems and the delivery performance could be tailored by varying their DS.