Structure-rheological relationship of capillary protein oleogels: The role of particle wettability

Abstract

The design of well-structured food colloids and functional interfaces provides new perspectives for developing healthy and sustainable foods in the future. In this study, we show how particle wettability affects the structural features and rheological properties of capillary oleogels, which are formed using colloidal zein particles with varying wettability from 77.8° to 106.7° as building blocks, creating a space-spanning network in oil via capillary attraction. Confocal microscopy was utilized to image the structural heterogeneities in the oleogels caused by variations in particle wettability, while rheological scaling analysis was used to describe the multiscale structural contributions of protein particles within the network. These changes in particle wettability led to large-scale structural heterogeneity and differences in the mechanical strength of the oleogels. As particle wettability increases, both structural homogeneity and mechanical strength improve, forming adjustable network structures from the capillary state (θ > 90°) to the pendular state (θ < 90°). The fractal dimensions of these oleogels also increases, suggesting that the fractal structural features within both inter- and intra-floc clusters become more densely packed. The results indicate that the structural features and mechanical properties of capillary oleogels can be tailored by modifying the wettability of protein particles to suit specific applications.