3D-printed milk: Researchers develop low-temperature technique to preserve nutrients

22 Sep 2020 --- Milk-based products can now be 3D-printed at room temperature without additives, thus preserving its temperature-sensitive nutrients while appealing to consumers on the hunt for clean labels.

Researchers from the Singapore University of Technology and Design (SUTD) have developed the direct ink writing (DIW) technique, which is now subject to “ongoing plans for commercialization,” a spokesperson tells NutritionInsight.

The research has been published in RSC Advances. Lead author and SUTD Ph.D. candidate, Lee Cheng Pau, states that the “novel yet simple” method can be used in formulating various nutritious foods, including those served to patients in hospitals for their special dietary needs.

“Cold-extrusion does not compromise heat-sensitive nutrients and yet offers vast potential in 3D printing of aesthetically pleasing, nutritionally controlled foods customized for individual requirements,” adds assistant professor Michinao Hashimoto, the principal investigator of the study.A variety of shapes were successfully printed, including a couch, a cloverleaf, a fortress and a wheel.

Sensory characteristics
The only ingredients are milk powder and water, which is added to control the rheology. The texture depends on the final shape and size. 

For instance, milk powder can be 3D printed as a rigid enclosure and filled with soft fillings such as blueberry syrup, chocolate syrup and maple syrup. 

Meanwhile, the taste is simply that of powdered milk. However, this can be altered for different applications. 

Printing time depends on the complexity of the shape and size. In the case of the small shapes pictured – which are no larger than a few centimeters – printing can be as quick as five minutes. 

Overcoming prior printing challenges
Traditionally, 3D-printed foods have often used selective laser sintering (SLS) and hot-melt extrusion methods. However, these methods are not always compatible with temperature-sensitive nutrients found in certain foods.

In the case of milk, which is rich in calcium and protein, these printing methods use too high a temperature to preserve the nutrients. 

While cold-extrusion is a viable alternative, it often requires rheology modifiers or additives to stabilize printed structures. Optimizing these additives is a complex and judicious task, according to the researchers. 

To tackle these limitations, the SUTD team changed the rheological properties of the printing ink. The printable ink needed to exhibit shear-thinning behavior, where the viscosity is low at a high shear rate to allow extrusion of ink from the nozzle. It also had to maintain its shape upon deposition. 

Extensive characterizations of the formulated milk ink were also conducted to analyze their rheological properties and ensure optimal printability.

Experimenting with other foods
The researchers also examined the potential capabilities of printing with other types of food. They successfully printed a 3D structure of a couch with milk ink and chocolate inks at different layers. 

The first few layers were printed with the milk ink, followed by a few layers with the chocolate ink. The subsequent layers were printed with the milk ink again.

Another demonstration used inks of chocolate, coconut, maple syrup and blueberry as the internal fillings. The scientists did this by printing the bottom layers of the 3D structures with voids using milk ink. 

Next, other syringes were used to fill the voids. Finally, the top layers were printed to close the voids. 

“Overall, our method of food 3D printing was readily extended to multi-food printing to create 3D models with materials possessing various rheological properties,” the researchers write. The researchers also investigated printing the milk ink alongside other foods. 

Printing takes on new frontiers
In recent years, printing is increasingly seen across the F&B landscape. In July, Givaudan partnered with Redefine Meat, which developed the world’s first Alt-Steak plant-based products using industrial 3D printing technology.

Also in the protein space, the International Iberian Nanotechnology Laboratory created M3atD, a 3D bioprinted model for cultivated meat design. Additionally, KFC-Russia is using 3D bioprinting technology to produce real chicken meat grown directly from the cell in cooperation with the 3D Bioprinting Solutions research laboratory.

Meanwhile, 3D printing is also shaking up the supplement industry, especially for personalized nutrition. Nourish3D uses the technology to combine seven different active ingredients into tailored nutrition stacks, based on consumers’ lifestyle and goals. 

Late last year, Rousselot flagged that its gelatin may be used for 3D printing within regenerative medicine. Meanwhile, the Yissum Research Development Company is using nano-cellulose to 3D print personalized food based on genetic markers, the microbiome and special dietary needs.

By Katherine Durrell