Effects of chitosan coating on quality and protein characteristics of large yellow croaker ( Pseudosciaena crocea ) during ice storage

This project aimed to evaluate the effects of chitosan (CS) on the quality and protein characteristics of large yellow croaker (Pseudosciaena crocea) during ice storage. Samples were treated with different solutions (10.0 g/L chitosan solution (CS1), 20.0 g/L chitosan solution (CS2), 1% acetic acid (AA), deionized water (CK)) for 15 min then stored at 4°C. Microbiological (total viable counts (TVCs) and psychrophilic bacteria counts (PBCs)), physicochemical (total volatile basic nitrogen (TVB-N), thiobarbituric acid (TBA) and texture profile analysis (TPA)) were used to analyze the quality of large yellow croaker. The changes of protein characteristic were analyzed by total sulfhydryl (-SH) content, Ca2+-ATPase activity and Fourier transforms infrared spectroscopy. The results showed that chitosan could effectively inhibit the microbial growth, and the hardness value was consistent with the reduction of protein characteristic indicators (-SH content and Ca2+-ATPase activity). For protein structure analysis, the amide I band and amide II band of CK group changed significantly, which indicated that α-helix might be transformed into β-fold or random coil. Therefore, 20.0 g/L chitosan treatment had better effect, it could extend the shelf-life for another 6 days, which had also protective effects on the secondary structure of protein and maintained its structure stability.