In order to improve the quality of squid surimi products, squid surimi gels were prepared using several types of organic salts under two heating conditions to study the effects of organic salts on squid gel properties. Compared with the NaCl group, organic salts reduced the solubilization capacity of myofibrillar protein, and significant (p < 0.05) decreases in the breaking force, breaking distance, texture, and water-holding capacity of the gel were observed in the sodium gluconate group, while significant (p < 0.05) increases in the breaking force, breaking distance, texture, and water-holding capacity of the gel were observed in the sodium citrate and sodium tartrate groups. Although the mixed addition of NaCl and organic salt improved surimi gel quality, the effective improvement was still lower than that of only organic salt. Rheological properties indicated that sodium citrate and sodium tartrate had high viscoelasticity. The squid surimi gel prepared by direct heating exhibited better properties than gels prepared by two-step heating. The chemical force of squid gel prepared with sodium citrate and sodium tartrate formed a stronger matrix than the gels prepared with other salts. For color, the addition of sodium citrate resulted in an undesirable color of squid surimi gels, while the addition of sodium tartrate improved the whiteness of the surimi gel. The results showed that the quality of surimi gel was dependent upon the choice of heating method and the types of salt used. Sodium citrate and sodium tartrate could significantly improve the gel properties of squid surimi. This study provides reliable guidance for improving the overall quality of squid surimi gels.

IntroductionThe production of the large yellow croaker has seasonal and regional characteristics, which is typically preserved on ice, possibly leading to its deterioration in a short time. Therefore, in this study, we focused on the effect of temperature fluctuation on the quality changes of the large yellow croaker during frozen storage.MethodsIn this experiment, the large yellow croaker was soaked in a low-salt solution, and physical and chemical properties, water-holding capacity, color, and protein characteristics of the muscle were investigated after repeated freeze–thaw (F–T) cycles and frozen storage.Results and discussionThe results show the deterioration of muscle quality of large yellow croaker after low-salt treatment was lower than that of the salt-free soaking group. The salting treatment significantly (P &lt; 0.05) enhanced the yield of large yellow croaker, which was 24.3% greater than the salt-free soaking group after 6 weeks of frozen storage. The microstructure of the salted muscle was more stable and maintained its cellular structure after F–T cycles and frozen storage. The b* value of the salt-free soaking group increased from b* value of the low-salt soaking group decreased from acceptable range. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis indicates the content of 17 kDa peptide decreased in the low-salt soaking group, and the peptides at 21 and 24 kDa increased during frozen storage. The results of the present study provide guidance for the optimal processing, transport, and storage of large yellow croaker, but the effect of salting on lipid oxidation and protein oxidation requires further study.

This study investigates the effects of heating method, setting time, and setting temperature on the gel properties, water holding capacity (WHC), molecular forces, protein composition, protein conformation, and water transition of Bombay duck (BD) surimi gel. The obtained results demonstrate that the best gel properties are obtained by two-step heating at 30°C for 120 min while the hardness was 10.418 N and the breaking force was 4.52 N. Gel softening occurs at setting temperatures greater than 40°C due to the effect of endogenous enzymes in destroying the protein structure and increasing the hydrophobic and disulfide interactions. Low-field nuclear magnetic resonance spectra confirm that high two-step setting temperatures induce gel softening and the destruction of the surimi gel structure, as evidenced by the increased water migration at these temperatures. Of all protein conformations in the gel, the β-sheet structure, decreases from 38.40% at 30°C to 11.75% at 60°C when the setting time is 60 min, is the most susceptible to gel softening. Overall, the data reported herein provide a scientific basis for the development of new BD surimi products on an industrial level.