3D printing our personalised grub of the future

A team of researchers from Singapore University of Technology and Design (SUTD) have developed a new way to customise the food that we eat.

Three-dimensional (3D) printing using food ingredients is currently the favoured approach to shaping foods with unique structures, textures and nutritional compositions.

“Printing food in 3D enables the customisation of nutrients, the creation of aesthetically pleasing meals and the modification of food texture to suit individual dietary needs,” said associate professor at SUTD Michinao Hashimoto, and principal investigator of findings published in the journal Future Foods as Multi-material direct ink writing 3D food printing using multi-channel nozzle.

Some repurposed food sources, such as okara (soybean dregs), orange peels and insect protein, tend to ward off appetites by their appearances and origins. By adjusting the printing parameters, however, researchers can incorporate edible and nutrient-rich ingredients from these unusual sources, and construct an aesthetically pleasing meal.

For the everyday person, this brings to the table a personalised and sustainable means to get their meals. This advancement could also help individuals with eating disorders or who have difficulty swallowing (dysphagic) customise their mealtime experience and improve their eating habits.

New approach for customised food

Researchers have successfully printed foods using chocolate, milk and vegetable inks, but these constructs are largely confined to single ingredients. Existing methods struggle with seamless transitions between materials, leading to fragmented prints and increased complexity in the machine printing process, according to Dr Lee Cheng Pau, the lead researcher of the current study.

One common approach uses multiple nozzles to hold and eject different food constituents, like having a box of coloured pencils to work with. Requiring careful machine design and nozzle alignment when printing, this approach has discontinuous interfaces, where different materials overlap, and has long printing times.

The research team is abandoning this method and taking inspiration from microfluidics. With dual inlets and a single outlet, this approach mitigates the intricacies of switching between multiple nozzles by combining the food pipelines before the printing stage.

Combining different food inks by intersecting junctions is not a trivial matter. Backflows into the ingredient inlets tend to happen with fluids of different rheological properties — such as flow and viscosity. For example, squeezing out a dab of toothpaste requires more strength than pouring out water. If the two were to feed into a single outlet, pushing out toothpaste would likely send some paste up into the water inlet.

To overcome the inlet challenge, the researchers had to carefully engineer the design of the food printer. The first step was to widen the exit outlet of the Y-junction in the printer to accommodate food ingredient inks that are high-yield-stress, which require more force to extrude. This change offers a lower resistance for the flow, preventing the ink from going up the wrong channel in the printer. In addition, it is necessary to account for the delay in the food ink transition. As the location for the switching between inks no longer happens at the printing nozzle, the researchers implemented an offset for the printing algorithm.

With this design, the team was able to demonstrate seamless and continuous printing between inks with vastly different rheological properties, with minimal backflow. To demonstrate the system, researchers printed the SUTD institutional logo and a fully functional QR code using different milk inks.

Overview of multi-material DIW 3D food printing. A) The printed line with two nozzles required switching of the nozzle positions, and the printed line was not collinear due to misalignment. This specially designed nozzle produced prints with no broken lines. B) Image of the fabricated Y-shaped nozzle. C) 3D printed edible QR code printed using the Y-shaped nozzle. Image credit: SUTD.

The team hopes to now optimise the design and technology further to accommodate more inlets and progress towards commercial scalability.

Lead researcher Dr Lee Cheng Pau said: “Our technology can be used to 3D-print foods consisting of multiple materials without compromising the printed structures and appearance.

“It can be applied in creating meals tailored to individual dietary needs, aesthetically pleasing dishes and interactive food experiences such as edible QR codes.”

Top image credit: iStock.com/Devrimb