Beyond Contact Angle: Reframing the Evaluation of Super-Liquid-Repellent Materials for Real Food Environments

Super-liquid-repellent materials hold significant promise for minimizing food residue, suppressing interfacial fouling, and enhancing the cleanability of food-contact surfaces. However, prevailing evaluation paradigms-centered on static contact angle, roll-off angle, and dry abrasion-fail to forecast long-term service performance in complex food-processing environments. Unlike idealized probes, real food matrices comprise proteins, polysaccharides, lipids, surfactants, and microbiota, driving interfacial behavior that is time-dependent, multicomponent-coupled, and dynamically evolving. Consequently, traditional static metrics are inadequate across temporal, chemical, and mechanical dimensions. Furthermore, while "fluorine-free," "edible," or "bio-based" labels offer design cues, they cannot substitute for rigorous, lifecycle-resolved assessments encompassing fabrication, aging, migration, and end-of-life impacts. This review delineates the fundamental mismatch between current evaluation frameworks and operational food environments, exposing latent safety and sustainability risks obscured by superficial green claims. We subsequently discuss a dynamic evaluation framework featuring multidimensional metrics and a tiered screening workflow, shifting the paradigm from endpoint-focused assessment to a process-based evidentiary chain. Finally, we outline future trajectories, emphasizing the transition from passive repellency to active fouling modulation and the co-design of performance, safety, and sustainability. This work provides a conceptual blueprint for updating evaluation standards and accelerating the industrial translation of food-contact super-liquid-repellent materials.