3D Printing of Foods. C. Anandharamakrishnan. Читать онлайн. Newlib. NEWLIB.NET

Автор: C. Anandharamakrishnan
Издательство: John Wiley & Sons Limited
Серия:
Жанр произведения: Техническая литература
Год издания: 0
isbn: 9781119671800
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Schematic illustration of inkjet printing.

      The most significant material properties that affect the print fidelity of the inkjet printing are the rheological and thermal behaviour of the food ink. In general, the inkjet printing system uses a low viscosity material for easy ejection of liquid through tiny orifice channels of the printhead. Material viscosity is a crucial factor that ensures the flowability of material. So, the desired material viscosity ranges between 2.8 and 6 mPas. While the viscosity above 10 mPas causes cavitation inside the printhead during the printing process and the viscosity below 2 mPas is not stable enough to form a droplet (Liu and Zhang 2019). The surface filling and decoration involve the jetting of food inks dispensing through the micro‐sized channels in the range from 20 to 50 μm. About 1‐pl (picolitre) of ink is dispensed during ejection of each droplets that typically range about 13 μm across (Xaar 2018). The principle of dispersion of ink involves the breaking up of a stream of droplets of the same volume with reduced surface area. The underlying process of ink‐jetting technology is based on the Rayleigh–Plateau instability phenomenon (Godoi et al. 2019). Another factor that affects droplet deposition is temperature. Variations in the temperature modify the rheological properties and influence the surface energy of the food inks. Application of lower temperature reduces the surface energy and spreading tendency of food inks (Willcocks et al. 2011). The ingredient composition is another criterion that must be optimized for achieving the desired flowability for fabricating 3D designs on food substrate. Only a limited range of food materials has been analyzed for inkjet printing, in which chocolate ink is the most commonly used ingredient (Lanaro et al. 2019). However, other food materials in form of emulsion, slurry, and suspensions have a great scope for 2D and 3D inkjet printing. Future studies on the analysis of different material supplies suitable for inkjet printing are required to broaden the food applications.

      2.6.2.1 Drop‐On‐Demand Inkjet Printing

      In continuous inkjet printing, the edible ink is continuously dispensed without any pause through a piezoelectric vibrating crystal at a constant frequency. The use of a high‐pressure pump creates a continuous flow that directs the liquid food ink through an orifice of smaller diameter ranges between 50 and 80 μm (Godoi et al. 2019). In some cases, the material flowability can be ensured by incorporating conductive agents into food ink to impart charges. The use of electrically charged conducting agents for improving the performance efficiency limits its application in food customization. The droplet generation rate of continuous inkjet printing is comparatively higher than the DoD inkjet printing. However, the resolution and precision of the produced images from DoD inkjet printing seem to be superior with neat dispensing than continuous inkjet printing. Willcocks et al. (2011) reported that the maximum resolution of inkjet printed images using a single head continuous ink‐jetting system of about 70–90 dots per square inch (dpi).

Schematic illustration of binder jetting.