A novel method for high-temperature microwave 3D printing of golden thread surimi: Combination of thermally reversible gelatin and κ-carrageenan

Microwave 3D printing of surimi has temperature limitations and transglutaminase dependence. The current study aimed to achieve microwave 3D printing of surimi at higher temperatures (45–80 °C) with the combination of thermally reversible gelatin and κ-carrageenan to eliminate reliance on the transglutaminase and improve the molding capacity of products. Our results showed single surimi cannot be stacked when printed at 45 °C while it can be successfully extruded and molded at 80 °C after adding a combination of gelatin and κ-carrageenan to surimi paste. According to rheological data, κ-carrageenan provided the surimi paste with good elastic properties while gelatin lowered the paste's viscosity when heated. Particularly, the microwave 3D printed surimi with 4.5% κ-carrageenan and 1.5% gelatin at 80 °C exhibited relatively optimum gel strength and mechanical characteristics. The results concerning water distribution and microstructure suggested that the microwave printing process could limit the flow of water and enhance the ability of the products to retain moisture, meanwhile, the products printed at 80 °C displayed a relatively more comprehensive gel network structure. Furthermore, molecular force analysis showed hydrophobic and disulfide bond contents increased significantly with the increase of κ-carrageenan at 80 °C, suggesting the promoted protein-colloid cross-linking during microwave heating. In general, gelatin and κ-carrageenan can effectively regulate the surimi gel process during microwave 3D printing at higher temperatures, and improve the molding capacity of final products, which provide a new pattern for the future food manufacturing.