Sunday, February 20, 2011

Hard Wired for Chocolate and Fries, So Delicious, and So Bad for Our Health: The Science of Food and Flavor:

“Flavor is a concept created in the brain,” an amalgam of the sensory impressions of smell, taste, and the tactile feel of food in our mouths, said White House Executive Pastry Chef William Yosses.

That interdependence and the singularity of each of the senses was demonstrated when Kraft Foods’ Jane Leland had audience members pinch their noses then pop a jelly bean into their mouths and chew on it. Taste buds instantly registered the sweet, sour, and gummy aspects of the treat, but not its flavor.

When the pinch was released, volatile aromatics circulated into the nasal cavity and its olfactory receptors. Each member of the audience instantly could tell if they had selected a similarly hued lemon or pineapple treat at this AAAS Annual Meeting symposium on perceptions and preferences of taste.

None can deny the importance of food. We are what we eat; food supplies the nutrients and energy for proper function and growth. But research has revealed that it goes deeper than that—we also are what our mother ate, because food can influence gene expression that can be passed down across generations.

Others have argued that the invention of cooking played a key role in the evolution of the modern human brain, and in fact made us human. The gut has limited capacity to digest and absorb the nutrients and energy of raw foods. Cooking breaks down cellular structures and makes a greater portion of food’s value available for the gut to absorb. It is the only way the energy intense demands of the human brain could be met.

So how do individuals and society manage the rich abundance of food that now characterizes this evolutionary blink of an eye we find ourselves in? Will we literally eat ourselves to death as a species, or can we learn how to modulate our good fortune?

Gary Beauchamp, director of the Monell Chemical Senses Center in Philadelphia, focused on salt during the AAAS symposium. It’s “the primordial narcotic,” he said. “Throughout most of human history it was very difficult to get, very rare, and very valuable,” which is why the tabletop salt cellars of monarch often were bejeweled repositories of that treasure.

“Throughout all of human evolution it has been rare, and now, all of a sudden, there is so much of it, it is almost free it is so cheap,” Beauchamp said. One of the health consequences is that 90% of Americans over the age of 50 have high blood-pressure, which contributes to cardiovascular and other diseases, and avoidable deaths.

Government policy since 1969 has recommended reducing salt intake, but Americans have paid little heed because, to the human palate, “salt tastes good and it makes food taste good,” said Beauchamp. It represses bitterness, particularly with vegetables, and makes food seem sweeter, more palatable.

Patterns of taste for salt are set early in life. He related how infants of two months reject a high-salt formula, but if continuously exposed to salty food, by the age of six months they come to prefer the food with a higher salt content.

Salt preferences can be dialed down over time and individual taste levels reset to prefer foods with lower levels of sodium. The Institute of Medicine recommended this approach of gradually reducing levels of salt in commercially prepared foods over a period of years as a key public policy element in reducing average adult consumption from 3400 milligrams to an adequate level of 1,500 milligrams of sodium a day.

Beauchamp did note that all cultures consume about the same amount of sodium in their diets, and that is roughly an order of magnitude (10 times) greater than what scientists believe is physiologically necessary for good health. It suggests to him the possibility that researchers really don’t know how much salt humans need. “Maybe there is something driving that consumption,” he said.

“If our genetic disposition is to savor fat, and salt, and things that are bad for us, what is a chef to do?” Yosses asked rhetorically.

The modern culinary movement has embraced innovation in seeking fresher flavors and healthier alternatives to old standbys. Yosses showed how the cream and eggs of a chocolate mousse could be replaced with another kind of protein, in this case gelatin. “You still get the same effect of a creamy chocolate mousse, and you actually get a better chocolate flavor” that is not hidden by the other ingredients.

Foam is one way to added air and structure to a substance such as tangerine juice, “to produce enhanced flavor on the tongue while maintaining portion size.”

“Any chef who wants to understand what he does and cook what he does, needs to learn about the food, about the sources, down to the molecular level,” Yosses said. “... Understanding the crystals [of a food] helps you as a chef to understand how to deliver a better, more satisfying product.”

The panel was organized by Al Teich, senior policy adviser to AAAS Science and Policy Programs, and Rieko Yajima, a senior program associate at AAAS. Yajima, the panel moderator, said the association has embraced cooking as a way to engage the public in the principles of chemistry and physics, because food is something to which everyone can relate.

Contacts and sources:
American Association for the Advancement of Science,
Bob Roehr

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