Pectin-stabilized emulsions: Structure-emulsification relationships, covalent and non-covalent modifications, and future trends

Background: Emulsions are thermodynamically unstable systems, and as storage time increases emulsions will undergo a series of destabilizing processes. The addition of emulsifiers can delay or even prevent these processes through steric hindrance and electrostatic repulsion effects. Compared with small molecule surfactants and proteins, polysaccharides (especially pectins) as emulsifiers have stronger steric hindrance effect and lower sensitivity to the changes in pH, temperature, and salt concentration in the environment. Scope and approach: This review discusses the factors affecting emulsion stability, structure-emulsification relationships of pectin molecules, and covalent and non-covalent modifications of pectin molecules. Key findings and conclusions: Large-sized pectin molecules have poor interfacial activity, and the interfacial mechanical properties and emulsification performances of pectin molecules can be improved through acid/alkali hydrolysis, enzyme modification, Maillard reaction, chemical cross-linking and electrostatic bonding, so as to obtain long-term stable emulsions.