Effects of starch–fatty acid complexes with different fatty acid chain lengths and degrees of saturation on the rheological and 3D printing properties of corn starch.

• Fatty acid structure affected the 3D printability of corn starch–fatty acid (CS-FA) complex gels. • The formation of CS-FA complexes inhibited the "extrusion swelling" of CS gels. • CS-FA complexes changed the microstructure of corn starch gel. • Rheological and printing properties of CS-FA gel highly depend on FA structure. • Complex gels with 12-carbon fatty acid had the highest printing accuracy. The effect of corn starch-fatty (CS-FA) complexes from varying carbon chain length and degree of unsaturation on the rheological and 3D printing properties of corn CS–FA complex gels. The CS-FA complexes with longer carbon chain lengths and lower saturation enhanced the ability of gels to bind water, promoting the formation of intermolecular hydrogen bonds. The CS-FA complexes inhibit retrogradation and increase the amount of bound water, thereby reducing the structural integrity and transforming the original skeleton structure into a flake-like structure. These changes in gel structure led to lower flow stress and storage modulus for CS-FA gels containing FAs with shorter carbon chain lengths and lower saturation, resulting in reduced "extrusion swelling" of the material and facilitating its extrusion. The decreased "extrusion swelling" of gel improved print line width and printing performance. The CS-FA complex gel-printed product with a 12-carbon chain FA has the greatest printing accuracy, thanks to its moderate G', flow stress, and viscosity. This study provides important information for the CS-FA complexes for the preparation of starch-based 3D printing materials. [ABSTRACT FROM AUTHOR]