Effect of food 3D printing process on the rheological properties of rice protein printing inks

This work used different statistical approaches to analyze rice protein's rheological properties (G', G'' and η*) before and after printing. The printing ink was prepared with 30% rice protein and 70% water, adding 0.5% of xanthan gum to stabilize the mixture. Two printing conditions were used varying layer height [1 and 1.5 mm], printing speed [50 and 35 mm/s], and nozzle diameter [1.2 and 1.7 mm]. Then, an oscillatory test was performed to measure the rheological properties before and after printing, in a frequency range of 0.1 to 10 Hz with stress of 1 Pa. Data were analyzed using a univariate, multivariate, and functional approach. In the univariate process, rheological data obtained at 1Hz and 10 Hz were considered and analyzed using a simple ANOVA with a confidence level of 95% (p < 0.05). For the multivariate approach, each frequency range of 0-10 Hz was considered like an independent variable, and an analysis of principal components analysis (PCA) was performed. In the functional analysis, each rheological curve was considered a continuous function rather than a series of discrete points, and principal component analysis functional (FPCA) was performed. Unlike the univariate analysis, which only showed differences in G`` A 10 Hz, the results of the multivariate and functional analysis showed the effects of the printing process on the rheological properties (G', G'' and η*), observing a consequence of different frequencies in the clustering of the sample. This allowed inferring that a complete analysis of rheological curves through a functional or multivariate approach provides information of interest to identify trends, patterns, variability, and relationships, being a valuable tool for the study and interpretation of rheological properties.