Who hasn’t fantasized about coming home after a long day and pressing a few buttons to receive a hot, home-cooked 3D-printed meal from one’s digital personal chef? It has the potential to render microwaves and traditional frozen TV dinners obsolete.
Engineers at Columbia University are working to make that fantasy a reality, and they’ve recently discovered how to 3D-print and cook layers of pureed chicken at the same time, according to a recent paper published in the journal npj Science of Food. Sure, it’s not as advanced as the Star Trek replicator, which could create entire meals on demand, but it’s a start.
Hob Lipson, co-author, is the director of Columbia University’s Creative Machines Lab, where the research was carried out. His team was the first to use the Fab@Home personal fabrication system to create multimaterial edible 3D objects with cake frosting, chocolate, processed cheese, and peanut butter in 2007. However, commercial appliances capable of printing and cooking food layers at the same time do not yet exist. There have been some studies into using lasers to cook food, and Lipson’s team thought this could be a promising avenue to pursue further.
“We noted that, while printers can produce ingredients to a millimeter-precision, there is no heating method with this same degree of resolution,” co-author Jonathan Blutinger said. “Cooking is essential for nutrition, flavor, and texture development in many foods, and we wondered if we could develop a method with lasers to precisely control these attributes.” The researchers used a blue diode laser (5-10 W) as the primary heating source, but also experimented with near- and mid-infrared lasers, as well as a conventional toaster oven, for comparison.
The researchers bought raw chicken breast from a nearby convenience store and pureed it in a food processor to achieve a smooth, uniform consistency. To avoid clogging, they removed any tendons and refrigerated the samples before repackaging them into 3D-printing syringe barrels. A high-powered diode laser, a set of mirror galvanometers (devices that detect electrical current by deflecting light beams), a fixture for custom 3D printing, laser shielding, and a removable tray on which to cook the 3D-printed chicken were all used in the cooking apparatus.
“During the initial laser cooking, our laser diode was mounted in the 3D-printed fixture,” the authors wrote. “However, as the experiments progressed, we transitioned to a setup where the laser was vertically mounted to the head of the extrusion mechanism.” “This setup allowed us to print and cook ingredients on the same machine.” They also tried cooking the printed chicken after it had been sealed in plastic packaging.
What were the outcomes? Laser-cooked chicken retained twice as much moisture as conventionally cooked chicken and shrank half as much while retaining comparable flavors. However, different types of lasers produced varying results. The blue laser was best for cooking the chicken internally, beneath the surface, while the infrared lasers were better for surface browning and broiling. The blue laser did achieve slight browning on the chicken in plastic packaging, but the near-infrared laser was more efficient at browning the chicken through the packaging. The team was even able to brown the packaged chicken’s surface in a pattern resembling grill marks.
“Millimeter-scale precision allows printing and cooking a burger that has a level of done-ness varying from rare to well-done in a lace, checkerboard, gradient, or other custom pattern,” the authors wrote. “Heat from a laser can also cook and brown foods within a sealed package… [which] could significantly increase their shelf life by reducing their microbial contamination, and has great commercial applications for packaged to-go meals at the grocery store, for example.”
The team served samples of both 3D-printed laser cooked and conventionally cooked chicken to two taste testers to ensure that the 3D-printed chicken still appealed to the human palate. Despite the small sample size, both taste testers preferred the laser-cooked chicken over the conventionally cooked chicken, owing to its less dry and rubbery texture and more pleasing texture.
One tester was even able to tell which sample was the laser-cooked chicken, noting a slight metallic taste from the laser heating. “Ever go to the dentist and get fillings done?” the tester asked the researchers. “They have a laser they use to seal the fillings and you get that smell—a little bit of an industry odor, a sharpness that you don’t get with normal chicken.”
This was essentially a proof of concept, with only chicken being used, but the authors are confident that the method can be extended to other model food systems, including other animal meats and grains. In fact, they wrote, “Laser heating of grain-based substrates that more readily absorb water should accelerate moisture loss and browning during cooking as well,”
In the future, the team hopes to investigate how to use multiple laser wavelengths to achieve both internal and external cooking at the same time. They also want to figure out how to reduce cross-contamination between cooked and raw printed layers, as well as how to create software that will allow users to customize their own 3D-printed meals in the future.
“What we still don’t have is what we call ‘Food CAD,’ sort of the Photoshop of food,” Lipson explained. “We require high-level software that allows people who are not programmers or software developers to create the foods they desire. Then we need a place where people can share digital recipes in the same way that we share music.”