Performance of carboxymethylation of deacetylated glucomannan in stabilizing oil in water emulsion

Abstract

Glucomannan, a high viscous polysaccharide, shows strong potential for oil stabilization and encapsulation. This study aims to enhance the lipophilic properties and emulsifying performance of glucomannan through a consecutive modification process involving deacetylation and carboxymethylation. The carboxymethylated glucomannan (C-GM) was then used to stabilize fish oil emulsion at different concentrations. The results show that modifying glucomannan through increased Na-MCA content and prolonged reaction duration significantly enhanced its degree of substitution, reaching up to 0.085. This increase in substitution led to notable improvements in the molecular weight and lipophilic characteristics of the polymer. The successful attachment of lipophilic groups following carboxymethylation not only improved oil affinity but also reduced the solubility, water absorption, viscosity, surface tension, and critical micelle concentration (CMC) of glucomannan, indicating a shift toward more hydrophobic behavior. Moreover, the thermal stability of the modified glucomannan was improved, as evidenced by a delayed onset of thermal degradation. Functionally, the C-GM demonstrated excellent emulsifying properties, achieving up to 97 % emulsifying activity and effectively maintaining emulsion stability with only 2 % phase separation after 10 days of cold storage. These enhancements highlight the potential of C-GM as a high-performance natural emulsifier for oil-based formulations.