Читать книгу 3D Printing of Foods - C. Anandharamakrishnan - Страница 39

As stated earlier, material extrusion is based on the FDM approach that is widely used for 3D printing of thermoplastics and polymers. However, for food applications, the same principle has been adapted for layered deposition of food materials that are extruded out through the printing nozzle with precise control over the temperature (Mantihal et al. 2020). The extrusion‐based 3D food printing relies on the continuous flow of material supply either in a semi‐solid paste, highly viscous slurry, or in colloidal form. The solid‐like elastic behaviour of the material supply is ideal for the proper extrusion (Liu et al. 2018a). Hence viscosity is one of the critical factors for the successful deposition of material through extrusion‐based 3D printing. Most of the food materials could be successfully 3D printed using the extrusion technique. However, material consistency is a significant criterion since not all material supplies possess a characteristic solidification behaviour upon extrusion. Considering this issue, the material supply must be pre‐processed adequately to enhance the flow behaviour and its printability (Liu et al. 2019b). The pre‐processing includes the reduction of moisture from the printing material supply either by drying or by concentration. Based on the printability, the food materials are categorized as printable, non‐printable, and alternative ingredients. The characteristic extrudability of non‐printable and alternative ingredients can be improved through the addition of food hydrocolloids such as xanthan gum, guar gum, acacia gum, and sodium alginate as an additive into the printing material supply (Gholamipour‐Shirazi et al., 2019). Material properties such as gelatinization, gelation, and emulsification are the basic mechanisms that support the stability of the printed layers in extrusion‐based 3D printing.