Carrageenan addition improves the melting temperature and 3D printing performance of the gelatin system

The sturgeon fish skin gelatin (FG) could not form gelation for printing at room temperature and must be hold its shape at low temperature after printing due to low melting and solidifying temperature, causing certain energy loss. The purpose of this study was to investigate the effects of various types (κ-carrageenan: KG; λ-carrageenan: LG; ι-carrageenan: IG) and proportions of carrageenan on the gelation properties and melting temperatures of sturgeon skin gelatin blended system and realize 3D printability at room temperature. The results showed that the turbidity of the blended systems increased significantly with adding 0.4%–0.8% carrageenan. Meanwhile, when the additive concentration of KG was 0.4%, the highest gel strength was 104.02 g. And the hardness and adhesive of gel were 5.44 times and 5.37 times of that single gelatin sample when the concentration of KG reached 0.8%. When IG was added, the melting temperature of the blended system could be improved most obviously, followed by KG, while LG could improve least. In addition, the blended system with IG could form a more dense and uniform network structure. The results of thixotropy showed the gel formed by the blended system had certain thixotropy, but the lag circle area is small resulted in the insufficient shape stability after printing. Among them, the blended systems with 0.8% KG and IG received successfully 3D printing at room temperature. In short, carrageenan has a positive effect on improving the gelation properties and applying in 3D printing of the sturgeon skin gelatin system at room temperature.