In situ rapid conjugation of chitosan-gum Arabic coacervated complex with cinnamaldehyde in cinnamon essential oil to stabilize high internal phase Pickering emulsion

Abstract

In this study, chitosan and gum Arabic coacervated complex (CGCC) were used to stabilize high internal phase Pickering emulsion (HIPE), and cinnamon essential oil (CEO) was incorporated into oil phase. The effects of CEO and CGCC concentration on the microstructure, rheology, gel strength and stability of HIPE were investigated. Benefiting from the enhancement of the hydrophobicity of CGCC by gum Arabic, in situ rapid interaction of CGCC with cinnamaldehyde in CEO occurred at the oil-water interface through Schiff base reaction, hydrophobic interactions and hydrogen bonding. This behavior could significantly reduce the interfacial tension and substantially increase the adsorption of CGCC at the oil-water interface to form a thick and dense interfacial layer. The addition of CEO (2.5%-3) significantly reduced the droplet size and increased the Zeta potential, and greatly improved the stability and gel strength of HIPE. Moreover, the addition of CEO reduced the concentration of CGCC needed to stabilize HIPE, reduced frequency dependence and critical strain of HIPE and improved thixotropic recovery rate. In particular, the presence of high concentration of CGCC (4%-3) flocculated to form flocs and thus could not effectively stabilize the emulsion. The results of this study provided a new approach for improving the emulsifying ability of CGCC to a stable HIPE system.