(178a) Additive Manufacturing of Food: Formulation and Printability Criteria

The
recent explosion of interest in 3D printing technologies has forced a number of
different industries to evaluate its potential as a viable production
technique. While great successes and advances are clear in certain industries
such as medical devices and aerospace other areas such as the food industry
have not yet found wide use for the technology.

The
ability to be able to selectively deposit material or molecules within a 3D
volume and hence, gradate the composition (e.g. via direct manufacture of
pores), offers the possibility for the control of complex structures for
altering texture, taste & functionality in food products. Such manipulation
of microstructures can allow regulation of fracture, breakdown or dissolution
mechanics during product use, opening up the possibility of a range of
functional and novel foods.

While
this manufacturing technique is largely unheard of in large scale food
production there is significant interest and innovation in crude ‘macro’ scale
food printing for the catering industry and niche food product markets. To
drive this technology forward a significant increase in the knowledge and
design rules of potential food materials for printing is needed coupled with a
focus on controlling structures at a smaller scale to build more complex
multicomponent systems. It is suggested that with this knowledge significantly
more sophisticated, and personalised products can be offered especially when
coupled with a point of sale or distributed manufacturing model.

Among
the current 3D printing methods for food applications (Chia & Wu, 2015;
Guo & Leu, 2013),
extrusion is a prevailing technique because it is easy to develop and it has
the broadest set of “inks”(Guvendiren et al.,
2016; Tan, Toh, Wong, & Lin, 2018). These inks are often divided into three groups
depending on the extrusion techniques (Godoi, Prakash, &
Bhandari, 2016):
cold extrusion, hot-melt extrusion, and gel-forming extrusion. Both hot-melt
and gel-forming extrusion must possess gel-forming mechanisms (Kirchmajer, Gorkin
III, & in het Panhuis, 2015; Sun, Zhou, Huang, Fuh, & Hong, 2015). In hot-melt extrusion,
semisolid ink is extruded at a relatively high temperature from the nozzle and
it needs to solidify almost immediately after extrusion to weld to the previous
layer (Sun, Zhou, Yan, Huang,
& Lin, 2018).
If the gel-forming mechanism is based on chemical cross-linking the reagents
are often harmful and are unlikely to be used for food design. In case of ionotropic
cross-linking and complex coacervate formation (Godoi et al., 2016), the number of edible
materials that can be used as inks is limited. However, in cold extrusion the
ink is made of a self-supporting material and the extrusion is generally
conducted at room temperature (Sun et al., 2018).

This
study initially investigates rheological properties and printability (shape
fidelity) of food-grade hydrocolloid pastes. The results show that the phase angle
and the relaxation exponent could be used to understand the solid and liquid
characteristics of paste behaviour during the cold extrusion 3D printing
process. If the phase angle is in the range of 3° - 15° and the relaxation
exponent is in the range of 0.03 -0.13 , the ink is self-supporting (Figure 1).
Since measuring phase angle in the viscoelastic region is relatively straight
forward, the phase angle could be used as a quick and effective means of studying
the printability of the formulation. The obtained knowledge can be used as a
design rule for food (hydrocolloids) printing processes to develop new
feedstocks for food 3D printing. Further progress to expand these design rules
into other edible material classes is ongoing.

Figure 1 Recovery index vs phase angle for the re-structured
samples

Chia, H.
N., & Wu, B. M. (2015). Recent advances in 3D printing of biomaterials. Journal
of Biological Engineering, 9, 4. https://doi.org/10.1186/s13036-015-0001-4

Godoi, F.
C., Prakash, S., & Bhandari, B. R. (2016). 3d printing technologies applied
for food design: Status and prospects. Journal of Food Engineering, 179,
44–54. https://doi.org/10.1016/j.jfoodeng.2016.01.025

Guo, N.,
& Leu, M. C. (2013). Additive manufacturing: Technology, applications and
research needs. Frontiers ofMechanical Engineering, 8(3),
215–243. https://doi.org/10.1007/s11465-013-0248-8

Guvendiren,
M., Molde, J., Soares, R. M. D., & Kohn, J. (2016). Designing Biomaterials
for 3D Printing. ACS Biomaterials Science and Engineering, 2(10),
1679–1693. https://doi.org/10.1021/acsbiomaterials.6b00121

Tan, C.,
Toh, W. Y., Wong, G., & Lin, L. (2018). Extrusion-based 3D food printing –
Materials and machines. International Journal of Bioprinting, 4(2),
1–13. https://doi.org/10.18063/ijb.v4i2.143

Kirchmajer,
D. M., Gorkin III, R., & in het Panhuis, M. (2015). An overview of the
suitability of hydrogel-forming polymers for extrusion-based 3D-printing. J.
Mater. Chem. B, 3(20), 4105–4117. https://doi.org/10.1039/C5TB00393H

Sun, J.,
Zhou, W., Yan, L., Huang, D., & Lin, L. ya. (2018). Extrusion-based food
printing for digitalized food design and nutrition control. Journal of Food
Engineering, 220, 1–11. https://doi.org/10.1016/j.jfoodeng.2017.02.028