Effect of protein-polysaccharide hybrid gelator system on the material properties and 3D extrusion printability of mashed potatoes.

Mashed potatoes (MP) are famous as ready-to-eat products due to their excellent taste and texture. Problems such as complex injection occur when MP is used as a 3D printing material. To improve the smoothness of MP loading into a 3D syringe barrel and its 3D extrusion printability, the effects of the protein-polysaccharide hybrid gelator developed with different gelatin-B (GB, 2%, 4%, 6%) and κ-carrageenan (KG, 1%) on the rheology and 3D extrusion printability of MP were studied. The rheological results showed that the MP developed a glass transition temperature by adding the hybrid gelator. Adding 1% KG+6% GB (w/w, dry base) to the hybrid gelator has good shear thinning and self-supporting properties and showed the best geometric accuracy. In the extrusion stage, the yield stress, the consistency index (K), and the flow behavior index (n) of MP were 470.69 Pa, 313.48 Pa·s, and 0.159, respectively. In the recovery stage, the shear recovery time is 30 s. In the self-supporting stage, the storage modulus and loss modulus are significantly higher than those of other groups and have the strongest mechanical properties. Moreover, water distribution, Fourier transform infrared spectroscopy, X-ray diffraction analysis, and microstructure of printed MP with different hybrid gelators were observed. The addition of hybrid gelators reduced the content of free water in MP. Hybrid gelators did not produce new functional groups in the printed materials and did not change the structure of starch. These results provide new insights for applying protein and polysaccharide hybrid gelators in 3D printing.