Microbial Survival, Sublethal Injury, and Recovery in Frozen Food Systems: Implications for Safety, Quality Deterioration, and Cold-Chain Control.

Freezing is widely regarded as a microbiologically protective process that suppresses growth and extends shelf life but rarely eliminates microorganisms. Microbial risk in frozen foods is, therefore, determined not only by survival during storage at -18°C but by post-thaw repair and growth during thawing and handling. This review synthesizes freeze-induced injury mechanisms, including membrane damage, osmotic stress, oxidative injury, and macromolecular disruption, and links them to physiological state transitions, lag phase behavior, and recovery potential. Rather than treating sublethal injury, viable but non-culturable (VBNC) physiology, spoilage, detection methods, and freezing-thawing processes separately, we integrate them into a recovery-centered framework for frozen food systems. Particular attention is given to food-matrix effects, including water redistribution, nutrient release, fat and protein composition, surface moisture, and oxygen availability, which influence microbial repair and regrowth. We further evaluate detection bias in culture-based methods, viability ambiguity in molecular approaches, and limitations of predictive microbiology models under freeze-thaw and high-solids conditions. We argue that frozen food safety and quality should be evaluated on the basis of post-thaw recovery potential rather than storage survival alone. Practical recommendations are provided for injury-aware detection, standardized freeze-thaw reporting, validation of analytical workflows, and control strategies across frozen food systems.