Globeandmail.com

Revolutionary molecules turn bland food bodacious

By CAROLYN ABRAHAM
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From Saturday's Globe and Mail
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Saturday, February 1 – Online Edition, Posted at 1:49 AM EST


In a small office just west of the New Jersey Turnpike, researchers are taking the human taste bud into a brave new world.

Here, it is not cream or milk that the employees of Linguagen Corp. add to their morning java, but a dash of a biological compound that fools their brain into thinking that black, bitter coffee is as smooth as a milky double latte: All the flavour, none of the calories, and the effects last only as long as it takes them to drain their mugs.

A quiet revolution is under way in the world of flavour research, blending chemistry, molecular biology and genetics to cook up recipes your mother never imagined: In this emerging field, it's not the food that will be modified, but you the eater.

Imagine a compound that could dupe your tongue into thinking bland oatmeal was hot-fudge-sundae sweet? Or another that could make kids hoover spinach like Popeye?

"You could make healthy foods taste better," Alejandro Marangoni, a food scientist at the University of Guelph, said of the new field. "Just blocking bitterness has huge potential. Somebody's going to make a lot of money."

Linguagen's "bitter blocker" compound, which received a U.S. patent this month, is the first chemical known to inhibit the taste of bitterness by altering human perception instead of flavour. But it's unlikely to be the last.

By temporarily suppressing or enhancing molecular signals in the taste cells that blanket the tongue, researchers at several centres are devising ways to trick the brain into believing it's eating something that it's not.

Food and drug manufacturers traditionally rely on sugar, salt, and fat to mask unpleasant flavours such as bitterness. But that unholy trinity lies behind a raft of public health problems, obesity, diabetes and high blood pressure among them.

"I'm excited about the possibilities of all of this; there are all kinds of applications," said Linda Bartoshuk, who works on human taste perception at Yale University. "The more we learn about taste, the more clever we are going to become at manipulating flavours."

Dr. Bartoshuk called Linguagen's bitter-blocker "the real thing."

"I've tried it myself," she said.

Mixing it with water and quinine, a common bitter ingredient in tonic water, Dr. Bartoshuk gulped it back with few worries about the bitter-blocker's safety. After all, the compound, adenosine monophosphate, or AMP, is actually a naturally occurring substance made up of nucleotides, the building blocks of DNA. AMP is found in a wide range of natural foods including breast milk.

As Linguagen officials like to point out, there are more than a few of us who have already tried it.

"It intrigues me that [AMP] might be doing the same thing in breast milk," said Dr. Bartoshuk. "Calcium compounds in breast milk are bitter and we have always wondered how supertaster babies [who are more sensitive to flavours] could stand that and maybe breast milk is a natural system using bitter-blockers."

So far, the company has found the only drawback of adding too much AMP to their coffees, either in the mug or the grinds, is that it generates the taste of raw fish in your mouth, said scientist Stephen Gravina, Linguagen's associate director.

The company, which spun out of research Robert Margolskee conducted at New York's Mount Sinai School of Medicine, received a U.S. government grant to hunt bitter-blocker compounds.

The need for such taste-altering technology is urgent in the pharmaceutical industry. Mary Poppins might have been happy to dole out a spoonful of sugar to help the medicine go down, but it's often not enough to persuade children or seniors to take their medication without a struggle.

In fact, children's cough syrup might well be among the first candidate products for AMP.

However, hopes for the novel technology have spread beyond the medicine cabinet to the kitchen cupboard. Food manufacturers and fast-food chains are anxious to present healthier products to their health-conscious consumers.

In the past three years, Kraft Foods Inc., the Coca Cola Company, Nestle and the Campbell Soup Co., which also owns such brands as Pepperidge Farm and Swanson, have signed major research deals with Senomyx Inc., one of the biggest biotech players in the rush to decode the genetics of taste.

The La Jolla, Ca.-based firm holds a range of patents on the genes that enable the detection of bitterness and an understanding of how human sweet and savoury receptors function.

Michael Jacobson, executive director of the Center for Science in the Public Interest in Washington, D.C., predicts that there are bound to be those who will find the prospect of biochemically tweaking taste buds just too much to swallow.

"Natural food advocates will probably hate the concept," he said. "This may be another step toward humankind's steady march towards processed foods."

Mr. Jacobson said he recognized the obvious need to alter the flavour of drugs, "particularly life-saving drugs, where taste is an impediment to taking them." But he also raised concerns that these new compounds could allow food manufacturers to use "cheaper, crappy ingredients."

"I once asked a pasta sauce maker how come you sometimes see corn syrup on the list of ingredients in a tomato sauce and he told me it was to mask the taste of cheaper tomatoes," said Mr. Jacobson. "We could see more things like that."

Guelph's Dr. Marangoni suggested cheese makers could work more quickly and cheaply if they didn't have to wait for the bitter peptides to mellow during fermentation.

Dr. Gravina said major interest in their bitter-blocker has poured in from the coffee world. "You could have cheaper beans that taste like more expensive smoother beans."

He said canned soup might also make a worthwhile product for the additive, which still has many hurdles to jump to reach market shelves.

It was only three short years ago that the genes involved in taste sensations were identified. Since then, however, the field has exploded with new findings that link biology with human appetite, diet and flavour preferences.

"There has been more discovered about taste perception in the last 36 months than in the last 360 years," said scientist Gary Beauchamp, director of the non-profit Monnell Chemical Senses Center in Philadelphia.

"This is going to be a very exciting time. It's due to the major advances in genetics, like the human genome project, that these bitter and sweet receptors have been found."

Dr. Beauchamp, one of the discoverers of the human sweet receptor, explained that genes make proteins that lock on to the taste receptor cell, which, through a complex process, sends the flavour message back to the brain.

While AMP may turn out to be an example of an unusually safe and natural blocking compound, he said, the big question is whether similar compounds can be added in sufficient, but safe quantities.

Linguagen's hunt for a bitter-blocker began with finding the protein that reacted to bitter molecules and its corresponding receptor in taste cells.

Dr. Margolskee showed that "knock-out" mice that were missing a gene that made the protein gustducin were so impervious to bitterness that they had no trouble lapping up water spiked with denatonium.

"That's the most bitter compound known to man," Dr. Gravina said. "They add it to battery acid so kids won't drink it."

The search then turned to finding molecules to block the gustducin protein in humans. AMP is Linguagen's first and most promising candidate. But Dr. Gravina said the company has also discovered several others.

It's estimated that humans have as many as 20 receptors for bitterness. For this reason, Dr. Beauchamp said it's unlikely one compound will manage to block all bitter flavours.

Interestingly, however, humans seem to have only two sweet receptors. They work in tandem, Dr. Beauchamp said, with the sweet molecule slipping between the pair.

That bitterness should demand so many more receptors makes sense, he said.

"Bitterness is an important signal that tells us, 'don't eat that, it's poison.' And there are many receptors because it's important that we don't make a mistake. But there are very few things that are sweet and dangerous, most things that are sweet are nutritive."

Linguagen is also chasing molecules that help transmit the sweet taste message from tongue to brain with an eye to mimicking these "sweet potentiators."

Dr. Bartoshuk said scientists have known for 100 years that the gymnema sylvester plant of India has the natural ability to suppress the sweet taste sensation: "But who," she said, "wants to do that?"


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