Food for thought: Milk prints and veggie options

Printed milky munchies

For people who have trouble swallowing, doctors will often suggest soft foods as a way to get enough nutrients and calories. And Michinao Hashimoto, a biomedical engineer at the Singapore University of Technology and Design, wants to see if 3-D printing can make some of these soft foods.

One of his experimental materials is milk—specifically, milk powder—which he whips up into a paste. The paste is laid down layer by layer through an extrusion system to make milky treats. But squeezing a paste into perfect formations isn’t easy, he tells Newscripts. A lot of non-Newtonian physics are at play, and too much heat might ruin the milk. It took a while to find the best way to make this system work at room temperature—a technique called cold extrusion—to make the treats (RSC Adv. 2020, DOI: 10.1039/D0RA05035K).

“It’s quite a nice complementary process to the 3-D printing,” Hashimoto says of cold extrusion. Because the technique doesn’t use heat, it can preserve nutrients and prevent the proteins from denaturing. In doing so, cold extrusion maintains healthy components of 3-D printed soft foods that heat might destroy.

Hashimoto has also explored how cold extrusion might work in the 3-D printing of chocolate, for which heat is usually required for melting. He doesn’t outright say if he needs volunteers to sample the results, but this Newscriptster would like him to know that she’s standing by.

Prioritized veggie victuals

Many scientists say Earth’s climate is changing, grazeable land is at a premium, and eating less meat would be better for the planet. But how to encourage such behavior when friends tell the Newscripts gang that nothing beats a regular hamburger?

Behavioral and environmental scientist Emma Garnett thinks she has the answer. The recent University of Cambridge PhD graduate asked: If vegetarian options were more available, would folks choose them over meaty treats (Proc. Natl. Acad. Sci. U.S.A. 2019, DOI: 10.1073/pnas.1907207116)?

“We will have these hunches about what will work to get us to change,” Garnett tells Newscripts. But, she says, it’s important to rigorously test whether the changes researchers make are actually doing what they’re intended to do.

For example, some people have suggested that presenting vegetarian meals before meat-based meals on cafeteria counters will prompt diners to opt for the veggie ones. To test how proximity might affect people’s decision-making, Garnett and her fellow scientists worked with the catering staff at two University of Cambridge cafeterias to swap out which entrée was closest to the entrance, the vegetarian dish or the meat-containing dish. In one cafeteria, she says, over the course of 7,700 meals, sales of the veggie dish went up 5 percentage points, from 18% to 23%, when the meatless meal was offered first. But in the other cafeteria, there was no difference.

After a little rooting around, Garnett surmised that the distance between the entrées might have something to do with why there was a difference in diner choices in one cafeteria but not the other. To test this hypothesis, in the cafeteria where veggie sales went up, the researchers had catering staff reduce the distance between the meat and nonmeat options from 181 to 67 cm. With the shortened distance between entrées, the sales boost disappeared, and in some cases, the option closest to the door was overlooked completely (Nat. Food 2020, DOI: 10.1038/s43016-020-0132-8).

Garnett says these types of tests are important because if we want to have better public health policies, we need to understand what drives humans to do something different. The answers, she says, are not always right in front of you.

Please send comments and suggestions to newscripts@acs.org.