Abstract Freezing technology is currently an important preservation method for aquatic products. However, during the long-term freezing process proteins, which are the main components of muscle tissue, are inevitably exposed to an environment containing oxidative stress inducing changes in muscle protein structure. It leads to irreversible physical and chemical changes causing deterioration in the quality of aquatic products and reducing their nutritional value. Therefore, it is necessary clarify in depth to control oxidative damage of muscle during freezing and storage to gain more insight into the mechanisms of freezing-induced protein oxidation. The mechanism of protein oxidation in fish freezing, the effect of protein oxidation on fish quality, and the current regulatory methods for delaying protein oxidation were summarized in this paper review. The purpose is to provide a new research direction for the research and application of quality control in the process of fish frozen storage.

Abstract Phospholipid (PL) have favorable emulsification ability. The simultaneous application of PL and protein is one of the research hotspots. In this work, the impact of egg yolk PL (EPL), soyabean PL (SPL) and their concentrations on the fish oil-loaded PL/gelatin (GTN)-stabilized emulsions were studied. The results suggested that SPL/GTN-stabilized emulsions comprised bimodal of droplets, and monomodal was observed in EPL/GTN, and GTN-stabilized emulsions. The related droplet sizes were as follows: 1.5% EPL/GTN < 1.0% EPL/GTN < 0.5% EPL/GTN < 2.0% GTN < 0.5% SPL/GTN < 1.0% SPL/GTN < 1.5% SPL/GTN.; and (4) Conclusion: The concentration of PL had significant effect on the droplet size and emulsion stability of the emulsions. The 1.0% SPL/GTN-stabilized emulsions demonstrated the optimal stability and droplet size when stored at room temperature for 15 days than emulsion contained PL. The addition of PL inhibited lipid oxidation and increased the rate of fatty acid release in vitro digestion. This work illustrated that PL/GTN-stabilized emulsions could potentially be a targeted delivery medium for nutrients or drugs.

Abstract Fresh aquatic products have high nutritional value, but they are easily susceptible to spoilage. Freezing as an effective preservation method could better retain the quality and safety of aquatic products. However, mechanical damage caused by ice crystals and the oxidation of proteins and lipids would inevitably bring about a reduction in the quality of the frozen product during freezing and preservation. This work summarized the important factors that affected the quality of frozen aquatic products, revealed the mechanism of deterioration of frozen aquatic products on the quality through sensory evaluation and changes in physiochemical indicators. In the context of high-quality development, some improvements in frozen fish preservation were proposed to provide theoretical basis and solutions to improve the quality and efficiency of fish processing.