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.
Keywords: emulsifying property; fish oil; gel property; rheological property; surimi.
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