Effect of pH adjustments on a novel micellar casein-based edible 3-dimensional printing formulation

Three-dimensional (3D) food printing holds the potential to help reduce food waste by precise portion control and use of materials that are produced in excess or are otherwise discarded. This relatively new technology is likely to undergo decreases in equipment costs. To take advantage of such prospects, we developed a novel micellar casein-based edible 3D printing formulation. Our formulation relies on a highly concentrated micellar casein solution (27.75%, wt/wt, final) along with pH adjustments (3.5, 4.0, 4.8, 6.7, 7.2, and 8.2) at chilled temperature (4-9°C) to avoid premature aggregation. In comparison to the natural pH of 6.7, both alkalinization and acidification past the isoelectric point of 4.6 enhanced both elastic and viscous moduli that enable for shape retention during and after extrusion from a 3D food printer. However, alkalinization led to smaller increases in the viscous modulus and did not lead to the shape retention that acidification to 4.0 or 3.5 does. Both acidification and alkalinization also resulted in rougher surface textures compared with the formulation at pH 6.7. Whereas the pH 4.8 formulation had inferior shape retention qualities compared with those at the other pH values tested, it had optimized water resilience, defined here as minimized swelling and dissolution of dried structures placed in water. Overall, we present a novel casein-based 3D printing formulation that could be printed while chilled, and with properties that could be modified by pH adjustments.