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Several kinds of emulsified surimi gels were prepared from different quality levels of Alaska Pollack surimi, and the relationship between the emulsifying stability (ES) of myofibrillar protein and the properties of the emulsified surimi gels was investigated. Fish oil emulsified into surimi gels enhanced the breaking strength, but this was decreased by denaturation of the surimi protein, and the rate of enhanced gel‐forming ability with emulsification decreased with decreasing ES. Expressible drip also decreased with emulsification; however, increasing amounts of lipid in the expressible drip were separated out from the gel upon protein denaturation of the source surimi. Scanning electron microscopy revealed that the shape of fish oil particles became irregular and some voids caused by oil leakage were observed with increasing storage period of source surimi. The results suggested that improvement in gel properties of the emulsified surimi gels was correlated with ES as well as the level of protein denaturation.

To improve the quality and functionality of emulsified surimi gels, the effect of pH and heating conditions on the properties of surimi gel fortified with fish oil was investigated. Results showed that pH conditions influenced the solubility and emulsifying properties of surimi proteins and that the gel properties were associated with the protein properties. Under direct heating, the highest gel strength was achieved at pH 8.0, in which condition the solubility was significantly higher than others. Higher emulsifying stability resulted in enhanced gel strength relative to that of the control group. However, the changes in the gel strength were not consistent under two‐step heating. In addition, the expressible moisture and oil content were found to vary depending on the pH values under both heating conditions. The corresponding changes in expressible moisture and oil content could be attributed to the high protein solubility and emulsifying properties of surimi proteins. Analysis of the dynamic rheological properties of the resulting surimi paste revealed that the gelation properties varied depending on the pH conditions during the heating process. In addition, the temperatures of myosin cross‐linking changed according to the structure of surimi proteins, which in turn varied depending on the pH conditions. Practical applications To improve the functionality of surimi‐based product, the fish oil was added to prepare surimi gel. pH and heating conditions play important roles in the gelation of fish proteins. Therefore, this study investigated the effect of combined pH and heating condition on the property of surimi gel fortified with fish oil. The emulsified surimi gel with fine texture was obtained at pH of 8–8.5; moreover, heating conditions (direct heating and two‐step heating) also influenced texture of emulsified surimi gel. These results provide the evidence to produce the emulsified surimi‐based product with the high gel strength, water‐ and oil‐holding capacity.

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.