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• Eye and dorsal muscles have the highest lipid and protein content, respectively. • Eye muscle has the lowest water holding capacity during frozen storage. • Frozen dorsal muscle has the fastest lipid and protein oxidation rate. • Eye muscle has the loosest microstructure. The quality of fish can change due to differences in the lipid and protein oxidation rates in different muscles. This study examined vacuum-packed eye muscle (EM), dorsal muscle (DM), belly muscle (BM), and tail muscle (TM) of bighead carp frozen for 180 days. The results reveal that EM had the highest lipid content and the lowest protein content, while DM had the lowest lipid content and the highest protein content. EM also showed the highest values of centrifugal loss and cooking loss, and the correlation analysis showed that these losses were positively correlated with dityrosine content and negatively correlated with conjugated triene content. The content of carbonyl, disulfide bond, and surface hydrophobicity of myofibrillar protein (MP) also increased with time, with DM having the highest values. The microstructure of EM was looser than other muscles. Therefore, DM had the fastest oxidation rate and EM had the lowest water holding capacity. [ABSTRACT FROM AUTHOR]

The search for cryoprotectants has garnered significant attention due to the susceptibility of myofibrillar proteins (MP) to freezing denaturation during frozen storage, leading to the degradation of surimi quality. In this study, we investigated the effects of fistular onion stalk polysaccharide (FOSP), a byproduct of dry fistular onion leaves, on the physicochemical properties of frozen surimi derived from bighead carp during storage at −20 °C for 150 days. FOSP-3, the primary constituent of FOSP, possesses a molecular weight (MW) greater than 4 kDa and consists of galactose (Gal), arabinose (Ara), glucuronic acid (GlcA), and glucose (Glc) in a molar ratio of 0.71:0.15:0.04:0.10. Our results from texture profile analysis (TPA) reveal that the addition of FOSP (4% and 8%) improves the gel strength, chewiness, and springiness of the surimi gel, with the most significant effect observed at FOSP (4%). Furthermore, the storage modulus G' (Pa) of the surimi/FOSP composite gel surpasses that of the control group (CK), indicating the superior springiness of the composite gel. Moreover, the inclusion of FOSP reduces centrifugal loss, suggesting an enhanced water-holding capacity of the surimi gel. Importantly, the presence of FOSP delays the decline of Ca2+-ATPase activity and the increase of carbonyls, while stabilizing the secondary structure of MP. Therefore, FOSP emerges as a potential cryoprotectant for the frozen surimi industry, offering promising advantages in enhancing the quality and stability of surimi during frozen storage. [Display omitted] • FOSP (4%) is optimal to enhance surimi gel properties. • FOSP maintained the water holding capacity of the gel. • FOSP retards myofibrillar protein (MP) oxidation. • FOSP preserves gel network and properties. [ABSTRACT FROM AUTHOR]

[Display omitted] • CC (compound cyoprotectants) showed cyoprotective effect in unwashed mince. • CC addition gel retained higher gel strength, WHC and immobilized water. • CC addition retarded protein oxidation of myofibrillar proteins. • CC addition protect myofibrillar proteins from structural changes. • Salted egg white improved the gel properties within 4 weeks. Silver carp is a type of Asian carp that poses a threat to the United States. Unfortunately, producing Asian carp surimi in the US has been unsuccessful due to the high cost. Thus, exporting Asian carp to China and other Asian countries in the form of frozen deboned fish mince (without washing) would be a new way to create commercial value. This study was to explore the effects of compound cryoprotectants CC (sucrose, sorbitol, and sodium tripolyphosphate) and CC + SD (salted egg white) on unwashed silver carp mince during frozen storage. In the presence of CC, unwashed mince exerted benefits on gel property and water holding property. CC was able to retard protein oxidation as indicated by the retarded carbonyl content and lower loss in sulfhydryl content. Based on indicators of content of salt-soluble protein, α-helix, myosin heavy chain and intrinsic fluorescence intensity, CC addition inhibited protein aggregation by protecting the protein structure. The inclusion of SD did not show a cryoprotective effect or synergistic antioxidant effect with sucrose-sorbitol, but SD improved the gel strength within 4 weeks of freezing. Thus, CC can provide cryoprotective protection during frozen storage of silver carp mince. CC + SD provides a reference for long-distance transport and off-site production of frozen silver carp mince. [ABSTRACT FROM AUTHOR]