Evaluation of rennet-induced gelation under different conditions as a potential method for 3D food printing of dairy-based high-protein formulations

Abstract

The rennet-induced gelation of milk proteins was evaluated as a potential method for the formation of 3D printed food structures. The effects of pH, [Ca2+], and temperature on the rennet gelation properties of milk protein dispersion with 15% (w/w) protein content were assessed using low amplitude strain oscillation rheometry. A cycled-temperature ramp (heating-holding-cooling) during rheological measurements was suitable to evaluate gel firmness development, as an imitation of the temperature profile in the 3D printing process. A factorial design considering two levels of pH (6.0 and 6.4), [Ca2+] (1.5 and 5.7 mM), and temperature (31 and 40 °C), showed that the pH, temperature, and its interaction were the main factors enhancing gel formation and the strength of the resultant gel. At pH 6.0 and temperature ramped to 40 °C followed by cooling to 15 °C, a very high gel strength (~8–9 kPa) was obtained. These results showed that rennet-induced gelation could be manipulated for developing printable dairy formulations.