Standard military rations are made in bulk, formulated to provide a complete packaged meal during field operations. But sometimes, soldiers need a specific nutritional fix to maintain peak performance—say, a jolt of caffeine for alertness on a mission during which sleep is scant, or a bolus of creatine to help with muscle recovery after an especially physically demanding assignment. To achieve that level of culinary nimbleness, researchers at the US Department of Defense’s Combat Feeding Directorate, which develops military rations for the US Armed Forces, are turning to an unusual appliance: a 3D printer.
In the directorate’s Food Engineering and Analysis Lab, located at a US Army facility in Natick, Massachusetts, Lauren Oleksyk and her colleagues are creating 3D-printed bars tailored to optimize performance in specific scenarios or to address the needs of individual soldiers. Printers that create such supplementary rations could one day be synced with wearable sensors that detect a person’s physiological profile and nutritional needs in real time, she says.
Three-dimensional printers deposit bits of materials—usually plastics—through a nozzle onto a surface to build preprogrammed shapes layer by layer. Manufacturers and home hobbyists alike are using them to make customized machine parts, medical implants, furniture, and even guns.
Although 3D printing has touched many industries since its invention in the mid-1980s, the devices are in their infancy when it comes to printing food. In the past decade, researchers in academia and industry have been recasting the software and hardware for sculpting plastic to printing concoctions of peanut butter and other ingredients. At the same time, they have been wrestling with how to make food that can flow through the tubes of a 3D printer be as palatable as the traditional stuff.
In a sense, 3D printing isn’t that different from other types of food manufacturing. “If you buy any packaged food at the supermarket, then you’re practically eating 3D-printed food already,” says Lynette Kucsma, cofounder and chief marketing officer at Natural Machines, which makes a food printer called Foodini. In many cases, food manufacturers already push food through machines and shape it. But what’s different about 3D printing is that the end users maintain full control of what comes out of the machine, she says.
That’s why she and a handful of other experts in the technology envision a future in which 3D food printers are just another way to cook at home. “We do believe that in 10 to 15 years, 3D food printers will become a common kitchen appliance like your oven or microwave is today,” Kucsma says.
The promise of 3D food printing is big—not just for institutions like the army—says Hod Lipson, a robotics engineer at Columbia University. The method’s potential for customization allows people to explore new culinary dimensions in their own kitchens, making tastes and textures that have never been created before. For example, Lipson’s team recently printed a seven-ingredient slice of cheesecake with an elaborate internal structure. Because of the ways they constructed the layers, biting into the cake released the taste of each ingredient in waves, says Jonathan Blutinger, a graduate student in Lipson’s lab.
The transformative magic in traditional cooking comes from combining ingredients and applying heat at the same time, so the novelty of 3D printing food would be even greater if researchers can figure out how to print and cook simultaneously, Lipson says. “We spend such a lot of our lives making food,” he says. “We broil; we panfry. Except for microwaves, [today’s cooking] is all techniques that are 1,000 years old.”
Lipson was among the first to explore 3D printing with food—and it wasn’t even on purpose. In the early 2000s, most 3D printers could print with only a single material at a time, but his team was trying to figure out how to print machine components such as batteries or actuators out of multiple materials.
To calibrate the printer for each material, Lipson’s students reached for food ingredients like cookie dough, cheese, and chocolate, which are easier to work with but have some of the same properties.
The food ingredients then “took on a life of their own,” Lipson says.
Initially, colleagues poked fun at the lab’s growing interest in food printing. But Lipson was drawn to the technological challenges. “I still have a hard time explaining this to my colleagues, but peanut butter is much more complicated [to work with] than aluminum,” he says. Its properties are not linear, and small fluctuations in temperature—even just a degree or two—change its rheological properties completely.
In 2006, Lipson colaunched the world’s first open-source 3D printer, called Fab@Home, which could be used for food, to encourage makers to experiment with the technology. Initially, Fab@Home and other early 3D food printers printed confectionary products such as cake frosting or chocolate because these foods’ consistency makes them so easy to pipe.
For 3D printers to become common kitchen appliances, though, the technology needs to mature. The hardware is pretty simple: it’s “literally a machine that can pick up a syringe of food and then shoot it out based on some kind of directed path,” Blutinger explains.
But there’s no standard software or hardware optimized for the specific challenges of printing food. “We’re using industry software designed for printing plastic and metal parts, and we have little hacks to make it work,” Blutinger says. The field also needs to amass standardized digital recipes that home cooks could download and use in their 3D printers, the way that makers can download designs for making plastic toys or tools. At the moment, a chef who wants to print an hors d’oeuvre out of hummus and couscous with a garlic-sage glaze, or a beet-and-walnut cream cheese drop, would have to painstakingly develop a recipe from scratch.
To create a printable food, researchers must mix and remix ingredients to adjust material properties such as viscosity, adhesion between the printed layers, and the rate at which different layers get deposited, all through trial and error. And at the end of the day, it’s still food, so they must also attend to its nutritional content and palatability.
Generally, for foods made with an extrusion printer, viscosity is an important factor. Some printers, including one in Oleksyk’s lab that relies on pneumatics, can print solids such as nuts.
“A big difference you have to watch out for with 3D printing of food versus 3D printing a plastic, for example, is gravity,” Kucsma says. When printing plastics, 3D-printer nozzles heat the material to its melting point as it comes out the tip, and the plastic later hardens. That process can work for some foods, such as chocolate, but not for others, such as peanut butter or cream cheese.
Ingredients that have the consistency of frosting are easiest to work with. Meats can be pulverized into that state, but vegetables, because of their high water content, may have to be combined with a thickening agent like xanthan gum, Blutinger says. He and his colleagues are also exploring ways to print nonpaste materials such as powders, solids, liquids, and gels. Pastes can also serve as the structural components that hold together oozier or more solid materials, says Michael Okamoto, a food material scientist in Oleksyk’s lab.
What’s more, the way in which the printer’s nozzles lay down the ingredients can modify a food’s density and its level of chewiness. These features affect how hard a person’s jaw must work to break down the food, which in turn changes the eating experience. Theoretically, these different design aspects of a printed food can affect an eater’s satiety, Oleksyk says. She and her colleagues are beginning to investigate how that might correlate with how much of a food a person decides to eat.
Satisfying all these requirements is far from trivial, even for a relatively straightforward concoction like the tailored nutrient bars that Oleksyk’s team is developing for soldiers. And if the goal is to make something with a complex structure, creating a printable version is exceedingly more complicated. For example, a company called Redefine Meat is using 3D printing to create plant-based products that reproduce the structure, texture, and taste of beef steaks.
“Meat”—which is muscle—“has a very sophisticated structure meant to provide the animal with the right function, mainly movement,” says Daniel Dikovsky, Redefine Meat’s head of innovation and technology. The company analyzes meat’s characteristics with a standard compression test and other custom tests to see how it changes and resists being chewed, which depends on the orientations of the muscle fibers. Redefine Meat also re-creates how the muscle fibers align with and adhere to each other, using 3D printers to deposit the company’s proprietary plant-based fibers. The idea, Dikovsky says, is to truly mimic the different components of a bite of steak, such as the muscle fibers, fat inclusions, and connective tissue, and to simulate the experience of eating it—all the way down to the juices, the smell, and the flavor.
Whatever the ingredients, what’s still unknown is how the 3D-printing process might alter a food’s nutritional profile. So far, the effect seems minimal, Okamoto says. Some nutrients, such as vitamin C, are inherently unstable, so forcing them through a printer’s tubing and syringe might degrade them, especially when heat is involved, he adds.
More recent efforts to combine 3D printing with cooking are adding a new twist to nutritional calculations. Lipson’s team added lasers to a food printer and used them to cook ground chicken breast as it emerged from the machine. The researchers are now working with Okamoto to test how laser cooking affects nutrient retention.
“Nobody has done laser cooking before, ever,” Lipson says. He speculates that integrating cooking into the process, whether with lasers or some other form of heat, will be what puts 3D-printed food on the map and transforms this process into a full-fledged form of making a dish, start to finish.
In addition to providing a novel way for home chefs to move beyond their microwaves and food processors, 3D food printing may have other uses.
For example, 3D food printing may help improve the appetites of people with dysphagia—difficulty swallowing, which can be caused by brain disorders like multiple sclerosis or Parkinson’s disease. Dysphagia often requires people to follow a diet of foods that have been run through a blender, draining an eater’s pleasure in eating. But 3D printing allows foods to be rebuilt in their original shape, Oleksyk explains. Eating peas with a fork, even if they’ve been reconstituted, is far more enjoyable than slurping them through a straw, she says.
Researchers are also investigating how 3D printing can be used to stave off hunger or provide nutritional support to people in low-income settings. C. Anandharamakrishnan, director of India’s National Institute of Food Technology Entrepreneurship and Management, is using the approach to develop snacks fortified with protein and fiber that can be provided as supplements in government-run programs focusing on women’s and children’s nutrition. The snacks could be printed in a rotating array of cartoon shapes and colors and potentially produced cheaply on a local level, Anandharamakrishnan says. His team created 3D-printable chocolate-based bars containing different amounts of protein and fiber that children deemed tasty in tests of acceptability. The institute aims to start pilot trials of the snacks in schools next year to study whether they boost kids’ nutritional profile.
Beyond these uses, there’s also the sheer gastronomical joy of exploring completely new food experiences. “So far, we’ve only tasted a tiny amount of things that somebody figured out how to make,” Lipson says. “There’s so much more that’s possible that we’ve never tried—because we didn’t have the tools.”
Alla Katsnelson is a freelance writer based in Northampton, Massachusetts, who covers the life sciences and would happily devour a 3D-printed steak. A version of this story first appeared in ACS Central Science: cenm.ag/3dfood.