Ozone-mediated microbial succession and kinetic for refrigerated grass carp (Ctenopharyngodon idella) fillets

This study aimed to characterize the ozonated water-mediated microbial succession and spoilage features of refrigerated grass carp (Ctenopharyngodon idella) fillets, and establish a sensory-calibrated shelf-life prediction model. Grass carp fillets were treated with 15 mg/L ozonated water (OZ group) or untreated tap water (CK group), then stored at 4 °C. 16S rRNA gene high-throughput sequencing was used for microbial community profiling, combined with culture-dependent isolation for spoilage strain identification, physicochemical assays, sensory evaluation, and kinetic modeling for shelf-life prediction. The results showed that ozonated water treatment significantly reduced the microbial diversity of fillets, with Pseudomonas, Shewanella, and Aeromonas identified as the dominant spoilage organisms. Among them, Pseudomonas helmanticensis exhibited the strongest spoilage potential, featuring the fastest growth rate, highest total volatile basic nitrogen (TVB-N) accumulation (26.69 mg/100 g at the end of storage), and most severe myofibrillar protein hydrolysis. Taking sensory shelf-life as the gold-standard endpoint, the minimum spoilage threshold of Pseudomonas was determined as 7.62 log₁₀ CFU/g. A shelf-life prediction model based on Pseudomonas growth was constructed using the modified Gompertz equation (primary model, R² > 0.98) and square root model (secondary model, R² > 0.93), which achieved high prediction accuracy (relative error < 2%) within the conventional cold chain range of 0-4 °C. In conclusion, ozonated water treatment retarded grass carp fillet spoilage by inhibiting microbial growth, and the established model enables reliable shelf-life prediction. This study provides theoretical and technical support for the preservation and quality control of aquatic products.