A multi-scale framework for texture design in whey protein-gellan gum mixed gels: From microstructure to sensation

Understanding how colloidal interactions regulate texture remains a key challenge for designing structured foods. -This study investigated the combined effects of ionic strength (50-260 mM) and gellan concentration (0-0.14%) on the microstructure, fracture mechanics, and oral processing of whey protein isolate (WPI)-gellan gum mixed gels. Results showed that ionic strength modulated the formation of fibrous or particulate protein aggregates, creating six distinct microstructures. Crucially, network connectivity and spatial heterogeneity were identified as the primary determinants of fracture modes. These structural attributes dictated the specific oral processing behaviors. Protein-continuous and bicontinuous gels exhibited high fracture energy and delayed crack propagation. In contrast, clustered protein particle gels showed the highest elastic modulus, requiring elevated masticatory muscles activity (up to 73 μV) and prolonged chewing. Particulate and gellan-continuous gels displayed low mechanical strength, resulting in plastic deformation and numerous fine fragments. Fine-stranded gels allowed rapid crack propagation, promoting rhythmic, high-frequency chewing via water lubrication. Finally, a predictive Bayesian mixed-effects model (R² > 0.97) quantified the contributions of multiscale variables to texture formation. This study establishes a mechanistic framework linking colloidal interactions to oral perception, guiding the rational design of protein-polysaccharide mixed gels.