Modification of plant and algal proteins through the Maillard reaction and complex coacervation: mechanisms, characteristics, and applications in encapsulating oxygen-sensitive oils

There is an increasing demand for plant and algal proteins as alternatives to animal proteins. This demand is driven by lifestyle choices and sustainability concerns. The demand for them is particularly strong as ingredients. However, the technofunctional properties of these proteins, such as solubility, emulsifying, encapsulating, and gelling, need improvement to meet the requirements of food products. Among the approaches to modify proteins, covalent conjugation with polysaccharides through the Maillard reaction and non-covalent complexation through complex coacervation have received increased research attention. This paper provides an overview of these two approaches in terms of their mechanisms, typical process protocols, and the characteristics of modified proteins. The application of covalent conjugates and complex coacervates as emulsifiers and encapsulating shell materials for unstable and oxygen-sensitive oils is also reviewed. Recent studies that have combined these two approaches to achieve improved emulsification and encapsulation outcomes are reviewed to provide insights into the mechanism by which previously conjugated proteins undergo complex coacervation with a second polysaccharide. Ultimately, this review intends to identify the most effective technologies for creating emulsifiers and encapsulating shell materials using plant and algal proteins, particularly to stabilise and protect oxygen-sensitive oils.