Grass pea protein as an emerging source of sustainable plant proteins: Structure, modification, functionality, and applications

Grass pea is a legume crop with a protein content ranging from 20% to 30%, primarily composed of approximately 66% globulin, along with glutelin (15%), albumin (14%), and prolamin (5%). Grass pea protein (GPP) ingredients are commonly isolated using alkaline extraction and acid precipitation methods. The water solubility of GPP ingredients is approximately 60% at neutral pH. However, the resulting functional attributes of these ingredients are relatively poor, which limits their application in numerous food and beverage products. This review describes the grass pea protein as an emerging source of plant proteins including structure, modification, functionality, as well as its applications in food systems. The functional attributes of GPP can be enhanced using various physical, chemical, and biological modification methods that alter the conformation, aggregation, or molecular weight of the proteins. Physical methods like ultrasonication, cold plasma, heat treatment, and high-pressure treatment, as well as chemical methods like protein-polysaccharide conjugation and enzymatic modification, have been used for this purpose. Modification techniques such as ultrasonication has the potential to enhance protein solubility by over 90% and also significantly improve emulsifying, foaming, and gelation properties of GPPs by more than two-fold. The properties of GPPs can be characterized using a variety of analytical methods including UV-visible spectroscopy, surface hydrophobicity, free sulfhydryl groups, Fourier transform infrared spectroscopy, circular dichroism, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In conclusion, GPP holds great potential for application in the formulation of plant-based foods and beverages in the food industry due to its good functional and nutritional properties.