Globular proteins as soft particles for stabilizing emulsions: Concepts and strategies

Many globular proteins are good emulsifiers or stabilizers for oil-in-water emulsions. It is generally recognized in the field that globular proteins tend to undergo a structural unfolding and rearrangement when adsorbed at oilwater interface, and as a result, a viscoelastic interfacial film is formed. However, more evidences are fast accumulating in recent years to show that globular proteins exhibit a great potential to perform as soft particles for stabilizing emulsions. This review mainly presents the state-of-the-art knowledge about the emulsification performance and interfacial stabilization of globular proteins, achieved in the recent several years, especially by our research group. A critical summary of current understanding about the emulsification and interfacial properties of globular proteins, as well as some limitations existing for the knowledge, is first presented. Then, the concepts, structural requirements and strategies for globular proteins as soft particles for stabilizing emulsions or high internal phase emulsions (HIPEs) are introduced in details. The effective strategies include, but are not limited to, choosing native glycated globular proteins or glycation with carbohydrates, strengthening structural stability of globular proteins by polyols (dissaccharides in particular), and pH adjustment. Finally, some advantages and limitations of globular proteins as soft particles for stabilizing emulsions or HIPEs are discussed. Due to the increasing interests from food industry and health wareness from consumers in developing safe emulsifiers, this review is of crucial importance for the understanding of the role of structural characteristics in emlusification and emulsion stabilization of globular proteins, as well as their ultilization as emulsifers/stabilizers in food industry.