3 D Printing has emerged as a promising technology that finds vast applications in many fields such as machinery, biomedicine, engineering but recently this innovative technology has gained a huge popularity in area of food manufacturing sector due to its various advantages like customized food designs, personalized nutrition, simplifying supply chain and broadening of the available food material with varied attractive color, shape, and size. It is an additive process in contrast to some conventional processes of manufacturing which are subtractive.
In conventional process like cutting, milling etc. the material is removed to form the required component, but in 3 D printing material is added as per requirement and design to be formed. Nowadays, it is studied at global level to attain new techniques related to process so that it can be feasibly translated on larger scale for production of high volumes of product. This technology requires printers or scanners for formation of component through this procedure. It is also known as Additive Manufacturing which takes digital input in the form of Computer Aided Design (CAD) model and creates solid three-dimensional parts through an additive layer by layer process.
Principle
The basic principle for 3 D printed food is solid free form fabrication i.e., the ability of food material to hold and produce a solid structure without getting removed. The extruder pen or the injector places in the layer as per the design sent from computer. The bottom layer is quickly solidified to build more layer on it. To complete this a laser guided system is widely used. Customization of 3D printing processes allow for mass customization – the ability to personalize products according to individual needs and requirements. Even within the same build chamber, the nature of 3D printing means that numerous products can be manufactured at the same time according to the end users’ requirements at no additional process cost complexity. The advent of 3 D printing has seen proliferation of products (designed in digital environment), which involves levels of complexity that simply could not be produced physically in other way. While this advantage has been taken up by designers and artists to impressive visual effects, it has also made a significant impact on market share for the companies.
Process
A 3D food printer comprises a food-grade syringe or cartridge that holds material, a real food item. 3D printing requires hardware and software to work in collaboration. Advanced 3D food printers are equipped with user-friendly interfaces and pre-loaded recipes with designs that can be easily accessed by the computer or even with a mobile or IoT device. Let us now understand the process of manufacturing food via printer in brief:
- Printing the Model
Depending on the design data, provided the printer lays down several layers of powder, liquid, paper, polymer, plastic, or other material depending on the material required. Printer resolution describes layer thickness and X-Y resolution in micrometers. 3D Printers give designers and concept development teams the ability to produce parts and concept models using a desktop size printer.
- Finishing
Though the printer-produced resolution is sufficient for many applications, printing a slightly oversized version of the desired object in standard resolution and then removing material with a higher resolution subtractive process can achieve greater precision. In this process the supports would be dissolved which might be used to support overhanging features in the model to be printed.
Types of Printing Techniques:
- Extrusion Based Printing:
In this method, melted material or paste like slurry is extruded out continuously from a moving nozzle, and welds to the preceding layers on cooling. This type of 3D food printing applied in chocolate printing and soft materials printing such as dough, mashed potatoes, cheese, and meat paste. Additional structural objects used for supporting the product geometry is removed after completion of the printing process.
- Selective layer Sintering
This method applies a power laser to selectively fuse powder particles together layer by layer finally into 3 D structure. In this method each cross section is scanned individually for fusion of all powder ingredients present in that cross section. After scanning each cross section, the powder bed is dropped, and a new layer of powder is covered on top. This process is repeated until the desired structure is achieved. If any unfused powder is left during process, then it can be recovered for next printing. It allows to produce free-standing complex 3 D structures with higher resolution. This method is specially used for powdered materials such as such as sugar, fat, or starch granule (low melting point). Properties like particle size, flowability, bulk density, laser type and laser spot diameter are critical to the printing precision and accuracy of fabricated parts.
- Binder Jetting:
The binder jetting process uses two materials: a powder-based material and a binder. The binder acts as an adhesive between powder layers. The binder is usually in liquid form and the building material is in powder form. A print head moves horizontally along the x and y axes of the machine and deposits alternating layers of the build material and the binding material. After each layer, the object being printed is lowered on its build platform. This method has the potential to fabricate complex & delicate 3D structures and produce colorful 3D edible objects by varying binder composition. But this method can be only used for powdered ingredients.
- Continuous Jet Printer
In this method, ink is ejected continuously through a piezoelectric crystal vibrating at a constant frequency. To get a desired flowability of the ink, it is charged by the addition of some conductive agents. Ink is ejected out from heads under pressure exerted by valve. Generally, the printing rates of drop-on-demand systems are slower than that of continuous jet systems. Resolution and precision of produced images are higher. Generally, inkjet printing handles low viscosity materials that do not possess enough mechanical strength to hold 3D structure. For formulation of food ink food hydrocolloids plays a vital role. A hydrocolloid is defined as a colloid system wherein the colloid particles are dispersed in water. A hydrocolloid has a colloid particle spread throughout water and depending on the quantity of water available that can take place in different states e.g., Gel or sol (liquid). Food Hydrocolloid can form and hold 3 D structure easily.
3D printing is a ground-breaking technology that can improve the nutritional value of meals and even address hunger issues in countries where fresh and affordable ingredients are inaccessible. Therefore, global food industry should adopt 3D printing technology to make food production more efficient and sustainable.
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