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Stories:
Chews Like Chicken
Chews Like Chicken
Five years ago the U.S. Food and Drug Administration gave processed foods manufacturers permission to tout soy protein-based products as "heart healthy." Shortly thereafter millions of cholesterol-conscious Americans found themselves sampling Boca Burgers, Tofurky and other not-so-convincing "meat substitutes." Better late than never, says an MU researcher.
"When the FDA approved the health benefit statement, they were in a sense endorsing what has been known and been part of the regular diet for thousands of years in China and other parts of the world, " says Fu-Hung Hsieh, an MU professor of biological engineering and food science. "In the U.S., soy has traditionally been used to feed animals, with only a secondary use for human consumption. This has begun to change."
Indeed it has. Industry reports indicate retail sales of soy-based products reached $4 billion last year, their highest level ever. But this is small potatoes, market watchers say, compared to their potential. The key to kicking up soy sales? Doing a better job imitating the taste and texture of real meat.
Hsieh (pronounced "Shea") counts himself among a handful of food scientists racing to make that happen. Already he has perfected production of a soy-based "fibrous meat analog" that may turn out to be the envy of the industry -- a product that looks, feels, pulls apart and, perhaps most important, chews like real meat.
The key to Hsieh's product is upping the moisture level in MU's twin-screw extruder -- a machine ordinarily used to produce dry, ready-to-eat breakfast cereals, snacks and pet foods. "These types of food require 15 to 25 percent water," says Hsieh. "Soy protein-based, fibrous meat analog is different because we are working with a much higher moisture content, up to 75 percent."
The process begins with powdered soy protein, similar to the stuff sold at health food stores, going into the top of the extruder. It is then blasted with water, seared with heat, and beaten with mixing paddles. "Moving through the extruder, the soy proteins melt. When they heat up, the proteins disentangle and then are forced to realign in the long cooling die, where the flow becomes highly laminar. As the protein melt cools, the outside exhibits a higher viscosity because it is cooler and flows slower than the inside region. This causes it to stratify," explains Hsieh. "All three things -- the realignment of the protein molecules, the laminar flow and the stratification -- contribute to the formation of a meat-like, fibrous structure."
The process takes only a minute or so, after which the finished product emerges in long, three-inch-wide strips from the machine's cooling die still slightly hot to the touch.
At this stage the strips look more like chew toys than chicken, but no matter. Already they are generating a buzz. MU's soy strips recently caught the attention of the media arm of the American Institute of Physics, for example.
"One thing the AIP does is seek out and produce features that air on news programs around the country," says Desiree Miller, an executive producer for Discoveries and Breakthroughs Inside Science, a group she describes as the institute's media partner. "We saw this as a real breakthrough for food processors and for the public's health." Not to mention the public's good eating.
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