Flavor controlled release behavior from novel high internal phase Pickering emulsion gels stabilized by zein-chitin nanocrystals complex coacervates: The models on phase equilibria and mass transfer

Abstract

Emulsion encapsulation techniques integrated with modeling analysis offer an innovative solution for flavor retention and release. Here, we used coacervate materials to improve the interfacial properties of a novel high internal phase Pickering emulsion (HIPPE) gel, facilitating retention and controlled release of five different flavors. We then elucidated the structure-function relationship using phase equilibrium and mass transfer models. At pH 6.5 and 7.5, the interdigital chitin nanocrystals (CNCs) combined with zein, forming zein-CNCs complex coacervates. Novel high internal phase emulsion (HIPPE) gels stabilized by coacervates had unique interwoven structures, smaller sizes (47.58 μm, 49.58 μm), and greater rheological properties (thixotropic recovery rate: 80.42%, 85.24%). The release behavior of emulsion with five flavors was monitored by gas chromatography in a homemade mouth model. Through partition coefficients and Harrison's mathematical equation analysis, novel HIPPE gels exhibited a lower partition coefficient $K_{ge}$, mass transfer coefficient $h_D$, and higher effective partition coefficient $K_{ge}^{eff}$. The results indicated that the coacervation layers promoted affinity with flavors, and slowed down vortex-induced diffusion, thereby moderating flavor outbursts and controlling long-term release of hydrophobic flavors. This study presents potential applications of coacervate-structured emulsions as innovative flavor delivery systems to enhance flavor retention and controlled release.