Limited Enzymatic Hydrolysis Pea Protein Isolate–Chitosan Nanoparticles as Emulsifier for Pickering Emulsions: Structural Change, Physicochemical Properties, and Encapsulation for Astaxanthin

In the study, hydrolyzed pea protein isolate-chitosan (HPPI-CS) was prepared by limited enzymatic hydrolysis for encapsulation of astaxanthin in Pickering emulsions. The structural characteristics of HPPI and HPPI-CS nanoparticles were analyzed to illustrate the stabilization mechanism of Pickering emulsions stabilized by HPPI-CS nanoparticles. Furthermore, physicochemical properties of emulsion, and encapsulation efficiency of astaxanthin in the Pickering emulsion were studied. The results showed that the particle size of HPPI decreased by 18.3%, with an increase of 1.3% in α-helix, 1% in β-turn, 1.7% in random coils, and a decrease of 4% in β-sheet. These alterations rendered the structure of HPPI more pliable, enhancing its capacity to adhere to the oil-water interface. The addition of a high oil phase resulted in an increase of the viscosity of HPPI-CS Pickering emulsion, leading to the formation of a gel network structure. This enhanced the stability and encapsulation performance of the emulsion for astaxanthin in vitro. This study offers a fresh perspective on the formation of Pickering emulsion, and a new approach for delivering astaxanthin for digestion.