Exploration of changes in rheological and spectral properties of rice protein inks before and after 3D printing

The aim of this work was to understand the effect of the printing process on food inks by applying the chemometric approach to analyze the rheological and spectral properties of rice protein. Rice protein was printed under two conditions (speed: 35 and 50 mm/s, layer height: 1.5 and 1.2 mm, and nozzle diameter: 1.7 and 1.2 mm). Infrared spectroscopy and oscillatory tests at 1 Pa between 0.1 and 10 Hz were performed before and after printing. PCA and k-means analysis of rheological and spectral data identified patterns and significant differences. The analysis revealed that 3D printing affects rheological properties, reducing structural stiffness and modifying the relationship between elastic and viscous behavior. Spectral vibrations associated with NH, CH3, O-H, and C=O functional groups indicated significant structural changes due to the printing process. These results suggest that the printing process influences food inks' rheological and structural properties. • Rheology of rice protein ink is affected by the 3D printing process. • Multivariate analysis identified complex patterns not visible in univariate analysis. • Mid-infrared analysis helps to interpret the rheological changes caused by printing. • Amide bands I and II (1500-1750 cm- 1 ) show differences after 3D printing.