Food Tasting Too Healthy? Just Add Scent

How scientists use smell to trick tastebuds—and brains

Can scientists make cardboard diet food taste like the real deal? iStock

Fat, sugar, salt: a taster's holy trinity. But eat them in excess, and you’ll find yourself facing an unholy triad of high blood pressure, heart disease and obesity. Sadly, as anyone who has tried diet ice cream or potato chips knows, the reduced sugar or salt alternatives of your favorite snacks tend to feature reduced taste as well.

But what if, instead of trying to make low fat or low sodium foods taste better, scientists could trick the brain into tasting them differently? That’s what French chemists are attempting to do with an imaginative device that identifies and isolates the natural aromatic molecules associated with your favorite tastes. When added to low fat or salt foods, those scents can deceive your tastebuds into thinking that cardboard-tasting potato chip is the real deal. 

This week, a team led by Thierry Thomas-Danguin, of the French National Institute for Agricultural Research's Center for Taste and Feeding Behavior and colleagues unveiled the device in Philadelphia at the American Chemical Society’s annual meeting. Its name is a bit of a mouthful in itself: the Gas Chromatograph-Olfactometry Associated Taste (GC-OAT). 

To develop the machine, Thomas-Danguin had volunteers smell real fruit juice aromas through an olfactoscan device, which uses a tube to deliver a steady stream of smell to the user. Then, one by one, he added the isolated molecules to find out which ones would change people's perceived sweetness of the juice. When participants ranked their perception of sweetness on a scale of one to ten, researchers found that some molecules caused them to perceive the juice as far sweeter than it really was, compared with samples featuring no added aroma.

This most recent study builds on previous work by Thomas-Danguin and colleagues, including research in which they added ham aroma to flan and found that it made the salty-sweet dessert taste saltier to people. Changes to the aroma alone caused some tasters to declare that a flan made with 40 percent less salt tasted the same as a regular version. 

The results of these taste tests are dependent on how intense the food's taste is in the first place. If foods already taste salty, for example, adding aroma doesn't make them seem much saltier. Foods with a medium level of saltiness, on the other hand, seem to be more easily manipulated. Adding a salty aroma even evened out the perceived saltiness of two salt water solutions when one had 25 percent less salt. 

Ultimately, the idea behind the device is that food companies can incorporate some of these specific aroma molecules to make healthier foods more tasty. The study was funded in part by French food giant L.D.C. and global food and consumer goods company Unilever, which has previously funded research showing it was possible to boost a person’s mood by having them smell someone else’s sweat.

Food makers frequently introduce products lower in fat, sugar and salt, Thomas-Danguin notes—but consumers don't always find them appetizing. “If the consumers find these products not tasty enough, they will add table salt, sugar or butter, and consequently the target is fully missed,” he notes. “I am convinced that through these strategies we can help people … learn to like these reduced levels.”

It’s long been known that certain aromas enhance the intensity of certain tastes, says Paul Wise, of the Monell Chemical Sciences Center. This phenomenon depends on a concept called congruence, which is the way your brain associates taste and smell together. “It usually comes down to the notion that you've experienced that taste and that odor together in the past in foods and beverages,” says Wise. “And you've developed a link so that the brain will then group these in a special way so that they interact.”

Thomas-Danguin's group even combined two different types of aromas to enhance the taste of a salty, fatty cheese: butter scent associated with the fat, and sardine odor associated with the salt. “You can actually see brain activity, the enhancement of certain taste responsive areas with congruent odors,” says Wise.

However, it may be possible to manipulate or even create these connections in the brain, he adds. For example, your brain can learn to associate certain odors with sweetness, even if the odor isn’t sweet, some studies have suggested. Australian researchers found that among people who have never smelled a lychee fruit, that odor didn't initially enhance sweetness. But after repeatedly pairing that odor with sucrose solution, the odor acquired a sweet note.

For dieters and health-conscious foodies, the field of odor-induced taste enhancement seems to hold tantalizing promise. But it isn't quite as simple as it looks. Picking odors that enhance sweetness might seem easy, but the odor also has to be a good fit with the dish. “If it somehow skews the flavor profile in a weird way, that could put people off,” Wise says.

In other words, you might not be a food snob, but your nose always knows when a combo just doesn't work.

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