Effect of molecular structure changes during starch gelatinization on its rheological and 3D printing properties.

Although the changes in molecular structure during starch gelatinization has been intensively investigated, how a relationship between starch rheological properties, printability, and starch molecular structure changes during starch gelatinization remains unclear. This research is focused on the molecular structure changes of corn starch (CS) gels caused by different treatment temperatures and their effects on CS gel rheological and 3D printing properties. With increasing treatment temperature, the leached amylose content and short linear chains (DP 6–12) of CS increase, whereas the contents of long linear chains (DP > 12) decrease, which influences the rheological and 3D printing properties of starch. Due to the presence of the original granules and crystalline structure, the CS-65 starch gel presented a poor storage modulus (G′), indicating poor 3D printing performance. The leaching of amylose induced the formation of new crystal and cross-linked network structures, which is beneficial for increasing its G′. However, the increase in short amylopectin linear chains (DP 6–12) reduced the degree of short-range order and hydrogen bonding interactions, which was detrimental to its G′ and yield stress (τf). CS-80 starch gel exhibited the largest G′ and shear recovery rate, showing the highest self-supporting properties and printing precision. Extremely high temperatures contributed to the densification of the starch gel structure, which led to an increase in τf and difficult extrusion. Overall, molecular structural changes caused by starch gelatinization are critical to its ideal rheological properties for 3D printing. [Display omitted] • Starch with different treatment temperature were processed by extrusion 3D printing. • Higher temperature increases leached amylose and short chains (DP 6–12) contents. • The chains with DP between 6 and 12 were detrimental to G′ and τf. • The leached amylose was conducive to the mechanical strength. • Extremely high temperatures leaded to the densification of the starch gel structure. [ABSTRACT FROM AUTHOR]