Written by: Sandeep Ravindran, Ph.D. | Issue # 99 | 2020
- Food printing is one of the emerging applications of 3D printing, but most existing methods either require high temperatures or additives.
- In a new study, researchers have developed a method to 3D print milk-based products with minimal additives while maintaining its temperature-sensitive nutrients.
- The technique could be used to create aesthetically pleasing, nutritionally controlled milk-based foods.
As 3D printers have become more affordable and accessible over the past 10 years, their potential applications have also increased. One emerging application of 3D printing is food printing, which could enable the creation of aesthetically pleasing food products with customized nutrients and internal structures (1-5).
3D printing of food typically requires either high-temperature or additives. “3D printing of food has been achieved by different printing methods, including the widely used selective laser sintering and hot-melt extrusion methods,” says Lee Cheng Pau, a graduate student in the lab of Assistant Professor Michinao Hashimoto of Singapore University of Technology and Design. However, these high temperature methods are not suitable for 3D printing foods such as milk (6-9). “Milk is rich in both calcium and protein, but as these nutrients are temperature-sensitive, milk is unsuitable for 3D printing using the aforementioned printing methods,” he says.
Methods that don’t require high heat, such as cold extrusion, generally require additives to modify the rheology—or flow—of the ink and stabilize the printed structures (10,11). For example, previous studies have 3D printed milk with additives such as Xanthan gum (12). “Optimizing these additives is a complex and judicious task,” says Pau.
Pau is the lead author of a new study demonstrating the 3D printing of milk at room temperature without extensive use of additives (13). The study used a 3D printing technique called direct ink writing with cold extrusion of milk ink made from powdered milk and water. “The concentration of milk powder allowed for the simple formulation of 3D-printable milk inks using water to control the rheology,” says Pau.
The researchers characterized milk inks made with different concentrations of commercially available milk powder in water. “Extensive characterizations of the formulated milk ink were conducted to analyze their rheological properties and ensure optimal printability,” says Pau. The researchers found that milk ink consisting of either 70 or 75 weight/weight percent milk powder in water was suitable for direct ink writing 3D printing, with the former being less viscous and thus easier to extrude than the latter.
Pau and his colleagues were able to use both these milk ink formulations to successfully 3D-print mesh structures as well as complex structures—such as a 3D model of a couch—that were stable enough to hold their shape. “The texture can vary depending on the final shape and size,” says Pau.
The researchers were also able to demonstrate multi-material printing using multiple syringes containing milk ink and other edible inks. The researchers printed a 3D structure of a couch with milk ink and chocolate inks at different layers, or a milk ink structure with different fillings. “For instance, the milk powder can be 3D printed as a rigid enclosure and filled with soft fillings such as blueberry syrup, chocolate syrup and maple syrup,” says Pau.
This kind of multi-material printing could be used to create a nutritious and visually appealing meal that combines different food inks and maintains milk’s temperature-sensitive nutrients. The method could also be extended to 3D print other edible inks at room temperature and with minimal additives, which could have a variety of applications in creating customized food products.
“This novel yet simple method can be used in formulating various nutritious foods including those served to patients in hospitals for their special dietary needs, or dairy manufacturers or restaurants to create 3D milk products,” says Pau. “Personal use of 3D printing in the kitchen, for the purpose of cooking, is also possible,” he says. “There are ongoing plans for commercialization,” says Pau.
The study thus expands the possibilities of 3D food printing by demonstrating a relatively simple way to modify the rheology of food inks with minimal additives without degrading their heat-sensitive nutrients.
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