Additive manufacturing and precise laser heating, two technologies not always associated with food preparation, have come together in Columbia University's Creative Machines Lab for the cooking of chicken.

As published in NPJ Science of Food, a project at the Lab has investigated how lasers could offer precise temporal and spatial control over heat delivery for cooking, broiling, cutting and otherwise transforming food products.

3D-printed food has been under development by the Lab's Digital Food team since 2007, and current additive manufacturing platforms can in theory deposit foodstuffs of suitable consistency with high levels of positional accuracy, just as they can for other manufacturing materials.

But although basic studies of laser cooking using such printed foods have taken place, none have previously investigated the use of lasers in the printing and then cooking of meats on a single machine platform or evaluated the taste of the results, according to the Columbia project.

"We noted that, while printers can produce ingredients to a millimeter-precision, there is no heating method with this same degree of resolution," said Jonathan Blutinger, project leader. "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 project retrofitted a commercial 3D printer to enable the processing and laser heating of puréed chicken and used it to produce single-layer square and triangular shapes of printed chicken at different millimeter-scale thicknesses. Application of the laser to create solid cooked structures was managed by the 3D printer's motion-control software.

Successful laser cooking of the chicken layers involved a number of variables, with the project having to consider "the energy required to achieve food safe temperatures; the cooling rates of lased chicken; weight and volume losses associated with laser-broiled chicken; and color changes in lased chicken," according the team's paper.

Experiments were also carried out to test the penetrative heating of different laser wavelengths through layers of simple plastic materials, potentially as a way to cook or brown foods while they remain within packaging - a significant commercial opportunity for convenience foods.

Cooking with software

The project carried out trials using 5 to 10 watts of 445-nanometer blue laser light as the initial heating source, before comparative tests with 980-nanometer near-IR and 10.6-micron mid-IR irradiation. Results showed that IR light browned the chicken more efficiently than blue light, and that the NIR light was best at successfully browning and cooking food through packaging materials. The laser-cooked meat "shrinks 50% less and retains double the moisture content," said the Columbia team.

In the part of the experiment that really matters, two taste-testers were asked to compare printed chicken cooked using the blue laser with equivalent samples cooked electrically. They declared that they preferred laser-cooked meat to the conventionally cooked samples, according to Blutinger.

The work indicates the possibilities of this new technology using relatively low-tech hardware and software, although as the team's paper notes, "software cooking is a relatively uncharted space."

"We need a high-level software that enables people who are not programmers or software developers to design the foods they want," said Hod Lipson, head of the university's Digital Food Group.