Effects of fish oil incorporation on the gelling properties of silver carp surimi gel subjected to microwave heating combined with conduction heating treatment

To understand the oil-protein interaction in silver carp surimi gel under microwave irradiation, the effects of fish oil (FO) incorporation on the gelling and microstructural properties of surimi gel subjected to microwave heating combined with conduction heating were investigated. Although FO incorporation into surimi gel disrupted the protein matrix, thereby decreasing (P < 0.05) the gel strength, the destructive behavior was remarkably remedied by microwave heating. The whiteness of the gel subjected to microwave heating was also elevated (P < 0.05) when the amount exceeded 6%. Furthermore, microwave heating significantly decreased (P < 0.05) the hardness, gumminess and chewiness of the gel, which indicated that a softer gel was obtained by this treatment. The results of expressible moisture content and T2 relaxation analysis confirmed that microwave heating facilitated the retention of water trapped in the protein network. The scanning electron microscope images revealed that microwave heating promoted the oil-protein interaction and triggered a more compact gel microstructure. Although lipid oxidation that inevitably occurred after FO enrichment of surimi gel increased, and the malondialdehyde content was effectively increased (P < 0.05) after microwave heating, it was apparent below the range for consumers acceptance. This study revealed that the gelling quality of surimi gel enhanced with nutritional FO could be improved by rational application of microwave energy for the fabrication of functional surimi-based seafoods.