Effect of pre-printing gelatinization degree on the structure and digestibility of hot-extrusion 3D-printed starch

Hot-extrusion 3D printing (HE-3DP) is an emerging technique to create customized food with desired structure and properties. This research is focused on the effect of pre-printing gelatinization degree on the structure and digestibility of rice and wheat starch gels after HE-3DP. The results show that the lamellar, crystalline and helical structures were destroyed, the compactness of nano-aggregates formed decreased significantly, the content of semi-bound water in the gel system increased, and the content of bound water decreased, and these changes were more significant with an increasing gelatinization degree. Interestingly, the ideal printability and digestion resistance of the printed materials could be obtained with the pre-printing gelatinization degrees of rice and wheat starches being 50% and 40%, respectively. Overall, the pre-printing gelatinization degree has been found to be an important factor in regulating the printability and digestibility of starch during HE-3DP.