Effects of Soybean Oil Addition on Gel Structure and Large Deformation Behavior of Frozen-thawed Surimi

In this study, the effects of soybean oil addition (1%, 3%, 5% and 7%) on the structure of surimi gels during freeze-thaw were investigated, and the first-order Ogden model was used to describe the relationship between the true stress and the true strain of surimi gels with different mass fractions of soybean oil under large compression deformation (stretch ratio of 0.4–1). The results showed that the addition of soybean oil to fresh surimi reduced the gel strength and enlarged the pores of the gel network. It was found that the addition of 5% and 7% soybean oil had a protective effect on the gel network structure of surimi after six freeze-thaw cycles. The gel strength of surimi with 5% and 7% soybean oil (319.30 and 338.64 g · cm, respectively) was significantly higher (P < 0.05) than that (286.04 g · cm) of the control group (without soybean oil), and the gel network structure was more complete than that of the latter. The Ogden model was fitted well to the true stress-strain compression response curves of fresh and freeze-thawed surimi gels with the addition of soybean oil (R² = 0.916–0.998). The model fitting results showed that the initial shear modulus changes of fresh and freeze-thawed surimi gels were consistent with the gel strength results. This study suggested that the addition of soybean oil at 5% and 7% can reduce the damage caused to the surimi gel structure by freeze-thaw cycles. The Ogden model can well describe the effect of soybean oil addition on the large deformation behavior of fresh and frozen-thawed surimi gels. These findings may provide theoretical and technical support for the quality improvement of surimi products and the control of transportation and storage conditions.