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Tan C, et al.

value. Two forming agents were then used to confer 3. 3D Food Printing Machines
printability, known as forming agent A (2%–3% w/w
sodium alginate, potassium alginate and/or carrageenan) In this section, various printers with different advantages
and forming agent B (2%–3% w/w calcium gluconate, and limitations will be described and evaluated.
calcium lactate and/or calcium chloride). Agent A 3.1 list and description of food printers
was mixed into the prepared food ink while agent B
was sprayed after every successive deposited layer. 3.1.1 Procusini 3.0 Dual (Figure 6A) by Print2Taste
The interaction between calcium ions and alginate/ [25]
carrageenan ensured that the previous layer was gelled GmbH, Germany
before a new layer was deposited on top of it. The Procusini is a food printing system known for its
The spraying of calcium salts onto alginates promotes relatively small form factor while still catering for a
gelling in a similar manner to the LM pectin gel large print area. It achieves this by allowing movement
systems. The alginate’s negatively charged carboxylate of the print bed in the y-direction. The trade-off in
2+
groups first form ionic interactions with the Ca ions. such a system is a constantly moving printout which
Following that, guluronic acid (instead of galacturonic may jeopardize print fidelity. Syringes are housed in
acid in LM pectin) residues encapsulate the ions via the a heated metal jacket and easily refilled by hand with
egg-box model, producing junction zones. As a result, a self-contained cartridges (Figure 7), containing up to
[23]
crosslinked gel network is formed . 85 grams of food paste material. Hence, the cleaning
For carrageenan, the gelling mechanism observed is required is minimal. Currently, the materials supplied
much more similar to gelatin. At high temperatures of up by Procusini include chocolate, marzipan and fondant.
to 80 °C, carrageenan is denatured and exists as random Reusable food-grade stainless-steel tips are also used.
coils. As they are cooled down to room temperature, the The print bed is held in place by magnets and thus
coils dimerise and form long fibrillar double helices. A allows users to quickly swap out a full plate for an empty
gel network is then formed when these double helices one, so that the next batch of printing can continue while
undergo further aggregation. This aggregation is plating or packaging finished products. The 3D designs
promoted by the presence of cations such as potassium are communicated to the Procusini from a nearby
2+
+
(K ) or Ca to shield the negatively charged sulfate computer or smart device via WLAN.
groups present on the carrageenan backbone from each
other. The cations also serve as co-ordination sites to 3.1.2 .Choc Creator V2.0 Plus (Figure 6B) by Choc
bring discrete double helices into close proximity to each Edge Ltd., UK [26]
[24]
other . The Choc Creator V2.0 Plus contains a 30ml syringe,
2.8 challenges and future work 0.8mm nozzle, y-direction moving print bed, all made of
food-grade stainless steel. It also contains a heated jacket
From the above examples, we can see that there around the syringe that prevents the chocolate from
are many hydrocolloids that one may use to confer solidifying in the syringe. Pre-loaded designs can be
printability to conventional food pastes or purees. Each printed using the LCD touchscreen control panel without
hydrocolloid comes with its own set of unique benefits the need of external electronics. There is also a USB
and inconveniences. For example, low temperature port for users who want to upload their own G-codes
gelling systems like gelatin will allow the user to prepare for printing original designs. The recommended food
foods that are best served without exposure to high heat. material to use is molten liquid chocolate only.
Conversely, this implies that gelatin-based food gel
cannot be served above its melting temperature. In the 3.1.3 Discov3ry 2.0 extrusion system (Figure 6C) by
case of HM pectin, the intrinsic sugars and acids in the Structur3D Printing, Canada [27]
base food product (such as in a strawberry jam) may be
leveraged upon as natural gelling promoters. These HM The Discov3ry 2.0 paste extruder is a universal extruder
pectin gels however will not be suitable for diabetics due that can be paired with most desktop 3D printer systems.
to high sugar content. Its unique dual syringe setup allows mixing of two feeds
Thus, it would be of great value to find an optimal in a spiral mixer just before the nozzle tip just before
mixture of synergistic hydrocolloids that can be used deposition. In non-food applications, this can allow
universally across all base food ingredients. However, proper and controlled mixing of two-part silicones or
due to the complex nature of food matrices, where pH, epoxy resins with curing agents. In the context of food,
temperature, ionic concentrations and internal molecular it could be used to mix gelling agents with gelling
structures are hardly constant, achieving this goal, if promoters. Each syringe can hold up to 60 mL of
possible, would be a particularly difficult challenge. material.

International Journal of Bioprinting (2018)–Volume 4, Issue 2 5