Effects of Combined ε-Polylysine and High Hydrostatic Pressure Treatment on Microbial Qualities, Physicochemical Properties, Taste, and Volatile Flavor Profile of Large Yellow Croaker (Larimichthys crocea)

The combined application of high hydrostatic pressure (HHP) and natural antimicrobials is a promising alternative for fish preservation. In this study, microbial qualities, physicochemical properties, taste active, and volatile flavor compounds of large yellow croaker (Larimichthys crocea) following combined ε-polylysine (PL) and HHP (PL-HHP) treatment (200, 250, and 300 MPa for 10 min, 20 °C) were investigated and compared to the fresh and PL samples. PL and HHP acted synergistically to give higher inactivation of microorganisms, with the total viable count, Pseudomonas, H₂S-producing, and coliform bacteria counts even undetectable under the PL-HHP treatment at 300 MPa. PL-HHP treatment had no significant effects on the surface color and lipid oxidation levels. However, the muscle color changed obviously in the PL-HHP samples at ≥ 250 MPa (p < 0.05), showing a distinct cooked appearance. Samples treated with PL-HHP showed better texture quality, and the maximum resilience and water-holding capacity were observed with the PL-HHP treatment at 200 MPa. The degree of myofibrillar protein denaturation increased by PL-HHP treatment with the elevated pressure. Significant elevations in 5′-nucleotides, free amino acids, and equivalent umami concentration levels were observed in the PL-HHP treated samples (p < 0.05). Furthermore, PL-HHP treatment exhibited a significant impact on the volatile flavor compounds of fish fillets, with significantly higher concentrations of alcohols, aldehydes, and ketones compared to the fresh and PL samples (p < 0.05). These findings show that PL-HHP treatment can be an effective alternative for the preservation and processing of large yellow croaker, offering new insights into developing safe aquatic products with enhanced taste and flavor profiles.