Warmed-Over Flavor in High-Protein Ready-to-Eat Foods: Divergent Mechanisms and Tailored Mitigation Strategies

The global market for high-protein ready-to-eat (RTE) foods is expanding rapidly, driven by consumer demand for convenience and nutrition. However, thermal processing and subsequent reheating frequently induce warmed-over flavor (WOF), a complex off-flavor characterized by rancid and stale notes that can severely compromise product acceptance. This review provides a systematic, cross-system analysis of WOF formation, moving beyond comparative volatile profiling to elucidate the fundamental mechanistic models underlying this defect. We critically evaluate three representative systems, heme-iron-driven lipid oxidation in meat, protease-mediated protein degradation in surimi, and synergistic Maillard-lipid co-oxidation in plant-based analogs. A central insight from this evaluation is that WOF is not a uniform phenomenon but rather a matrix-specific issue dictated by intrinsic compositional and structural factors. Consequently, effective mitigation requires equally tailored interventions. While natural antioxidants and advanced packaging show promise, their efficacy is constrained by the specific biochemistry of the food matrix. Future research should prioritize a shift from descriptive volatile profiling to predictive, mechanism-based science. This will require integrating multi-omics technologies to dynamically map formation pathways and rationally designing delivery systems and smart packaging to build WOF resilience into next-generation RTE foods.