Temperature fluctuations during storage and transportation can compromise the quality of aquatic products. In this study, Pacific salmon bone collagen (SBC) was extracted from Pacific salmon bones and used to prepare a salmon bone collagen emulsion (SBCE). Pacific salmon fillets were treated with SBC, and their antifreeze activity was measured in terms of texture characteristics, moisture retention, color difference changes, and flavor stability during multiple freeze-thaw cycles. Subsequently, the physicochemical stability of emulsions with different oil contents was evaluated under ambient storage, centrifugation, and freeze-thaw challenging. Antifreeze efficacy was evaluated by subjecting the Pacific salmon fillets with SBCEs during freeze-thaw cycles. Studied the potential of SBCE freezing and thawing to maintain the quality of Pacific salmon. The results showed that emulsions containing 60%–70% oil phase exhibited the highest stability. Among formulations, SBCE2.0 most effectively preserved texture, reduced moisture loss, and limited denaturation and aggregation of myofibrillar proteins. Overall, SBCE significantly alleviated ice-induced quality loss in fish product and shows promise as a natural antifreeze agent for aquatic products.

This study aimed to explore the effect of phosphorylation on the zinc-chelating capacity of sea cucumber peptides and the gel properties of mackerel surimi. Zinc-chelating peptides were prepared by incubating 50 mg/mL phosphorylated sea cucumber peptides with different concentrations of 5 mmol/L zinc sulfate and characterized for molecular mass distribution, amino acid composition, Fourier transform infrared (FTIR) spectra, ultraviolet-visible (UV-Vis) spectra, fluorescence spectra, zinc-chelating capacity, molecular particle size, secondary structure, and surface hydrophobicity. Meanwhile, NaCl, ZnSO₄, the phosphorylated peptides, and their zinc chelates were added separately to mackerel surimi to study the effects of zinc-phosphopeptide chelates on the texture properties, microstructure, and flavor of mackerel surimi. The results showed that chelation with zinc sulfate at a mass ratio of 1:1 resulted in significant structural changes in the phosphopeptides, and the zinc-chelating capacity was significantly enhanced. Addition of the resulting product to mackerel surimi resulted in the maximum elasticity (0.98), hardness (7979.10 N), chewiness (4479.42 mJ), viscosity (8032.10 N·s/m²), and cohesiveness (0.92), as well as in the highest umami intensity. Under the action of zinc ions, myosin heavy chains formed large aggregates through cross-linking, resulting a uniform and dense gel microstructure. Therefore, the addition of zinc-chelating phosphorylated sea cucumber peptides mackerel surimi could significantly improve its gel properties.

Protein denaturation induced by ice crystal formation is the main contributor to the deterioration of fish quality during frozen storage. This study aims to extract hydrolysates capable of inhibiting protein denaturation from sea cucumber ovum protein using three types of proteases (pepsin, trypsin, and neutral protease). The enzymatic hydrolysates of sea cucumber ovum protein are capable of stabilizing protein structures through interactions and preventing protein unfolding and aggregation caused by various factors; thus, they are potential protectors against protein denaturation. This study investigated the effectiveness of various enzymatic hydrolysates of sea cucumber ovum protein in mitigating the quality deterioration and oxidative reactions of mackerel under freeze-thaw cycles. The results show that an enzymatic hydrolysates of sea cucumber ovum, identified as sea cucumber ovum protein neutral protease hydrolysate, efficiently maintained the textural properties and oxidative and conformational stability of mackerel fillets during frozen storage. In addition, sea cucumber ovum protein neutral protease hydrolysate inhibited water migration and microstructural damage to myofibrillar proteins during the freeze-thaw cycles, thereby maintaining overall fish quality. The results of this study indicate that sea cucumber ovum protein neutral protease hydrolysate is a promising candidate for sea cucumber ovum use in marine-based food preservation technologies.