Carboxymethyl tamarind seed polysaccharide/chitosan complexes through electrostatic interaction stabilize high internal phase emulsions: Roles of the mass ratio and oil-water interfacial activity

In this research, a novel polysaccharide-based complex system was developed through self-assembly driven by electrostatic interactions between carboxymethyl (CM)-modified tamarind seed polysaccharide (TSP) and chitosan (CS). First, the carboxymethylation of TSP was confirmed successfully. Then, the relationships among the morphology, physicochemical properties and interfacial activity of CMTSP/CS complexes with different mass ratios (1:5, 1:3, 1:1, 3:1 and 5:1) were systematically investigated. The turbidity of the complex solution gradually increased with higher mass ratios (CMTSP:CS) and pH values. The size of the complex initially decreased and then increased as the proportion of CMTSP increased. The CMTSP/CS complex at 1:1 displayed the smallest particle size, supreme surface wettability and strongest interfacial activity. The microstructure and rheological properties of emulsions stabilized by CMTSP/CS complexes were characterized. CMTSP/CS complexes at 1:1 and 1:3 exhibited enhanced emulsifying capacity and better viscoelastic attributes. Remarkably, stable high internal phase emulsions with 85% oil concentration could be formed using very low concentration (only 0.05 wt%). These findings suggest that CMTSP/CS complex-stabilized emulsions have great application potential as a new oil-in-water system.