Precise additive food manufacturing: Printing of millet dough, characterization, and comprehensive printability assessment

The research aims at the development of 3D-printed millet-based composite dough cookies from a selected formulation, among 31 formulations, with the best printability and stability. The dough comprises composite pearl and amaranth millet flour in an equal ratio (20-40 g), shortening (10-30 g), jaggery (12-22 g), and water (25-35 g). In stage one, a comprehensive analytical printability assessment of printed construct in terms of printing precision, printing rate, and stability is conducted. The defects in the printed constructs are identified using 3D scanning technology. In stage two, five best formulations are screened among 31 formulations, based on the printability assessment, print stability, and minimum defects. Rheological and textural analysis of screened formulations was conducted to characterize the dough and identify properties required for print stability. The best printable formulation to construct a complex shape, with ease of printing, better structural stability, and better shape retention after baking, comprises composite flour of 40 g, 30 g shortening, 22 g jaggery, and 25 g water. The best formulation having print score of 6, printing precision for cylinder, heart, and astronaut shape are 98.27%, 94.49%, and 95.51%, respectively. The printing stability for cylinder, heart, and astronaut shape is 98.79%, 99.53%, and 96.50%, respectively. The higher storage, complex modulus, and highest yield stress and hardness result in better print precision and stability. A novel strategy for the detection of defect in 3Dprinted constructs was presented, utilizing 3D scanner. PRACTICAL APPLICATION: By focusing on 3D food printing (3DFP) of millet-based dough, the research targets a growing market segment seeking alternative and health-conscious food options. It aligns with industry trends toward diversification and customization in food production, catering to a discerning consumer base with varying dietary preferences and requirements such as "print on demand." Furthermore, integrating 3D scanning technology for defects detection and enhance the quality control measures, ensuring consistency in printed food products. The complete rheological and textural characterization of the best printable construct are studied in detail. The dough formulation was prepared without any additives or preservatives.