Ingredient-water interactions influence the 3D printability of pea-based food materials

The nutritional composition of 3D-printed foods can be modified by altering ingredients to achieve personalized nutrition. The type and concentration of ingredients are known to affect the rheology and ultimately the 3D printability of food inks. This study aimed to evaluate the impact of changing composition, i.e. macronutrients and water content, on ingredient-water interactions and 3D printability of pea-based inks. Ingredient mixtures containing insoluble pea fibre, pea protein, and native pea starch were analyzed for their interactions with water using three methods: water holding capacity (WHC), farinograph, and time domain nuclear magnetic resonance (TD-NMR). Measured WHC of ingredient mixtures was found to be higher than the WHC calculated based on composition and the WHC value of individual ingredients, suggesting that ingredient-water interaction is influenced by composition. The farinograph was used to mix powdered ingredients with water to form inks and to record the changes in torque during mixing. The water absorption of mixtures was determined by using a baseline torque of 2±0.2 Nm, which was identified using well-printable inks. The water absorption value increased with an increase in protein content. Furthermore, TD-NMR diffusion constant results showed that pea protein binds water more tightly compared to fibre and native starch, indicating that the printability of inks was affected more by changes in protein content. To conclude, these findings highlight the impact of ingredient-water interactions on the printability of food inks, which enables more efficient formulation of printable inks.