Effects of ε-polylysine and rosemary extract on the quality of large yellow croaker (Pseudosciaena crocea) stored on ice at 4 ± 1°C.

To evaluate the quality changes in large yellow croaker (Pseudosciaena crocea) with ε-polylysine and rosemary extract stored on ice at 4 ± 1°C. About 0.1% ε-polylysine (PL) and 0.2% rosemary extract (RE) were individually or in combination with each other were treated with samples. Samples treated with deionized water were regarded as control check (CK) group. Physicochemical (texture profile analysis (TPA), pH, total volatile basis nitrogen (TVB-N), thiobarbituric acid (TBA)), endogenous enzyme activity (cathepsin B and D), proteolytic degradation (Trichloroacetic Acid (TCA)-soluble peptides and Sodium Salt-polyacrylamide gel electrophoresis (SDS-PAGE)), microbiological (Total viable count (TVC), Shewanella bacteria count, Pseudomonas bacteria count, Psychrophilic bacteria count) and sensory evaluation were conducted during the whole storage. As a result, PL + RE could delay the increase in pH, TVB-N, TBA value, and improve the texture attributes compared with the CK group. In addition, PL + RE could inhibit cathepsin B and D activities, protein degradation, and microbial growth effectively. Moreover, the shelf life of samples could be prolonged at least 4 days when compared with the CK group according to the quality index method (QIM) and physicochemical assay, indicating that the PL + RE treatment could maintain the quality of large yellow croaker more effectively. PRACTICAL APPLICATIONS: The preservation of fish is becoming increasingly important in aquatic products. According to the fence theory, a combination of biopreservatives with different functions could be used to maintain the freshness synergistically. Furthermore, this research indicates that the combination of ε-polylysine and rosemary extract, a promising method for the preservation of aquatic products, could slow down the deterioration of large yellow croaker and prolong its shelf life.