Flavor Modulation in the 21st Century

Symrise, Teterboro, NJ, released a sweetness enhancer that uses the carbohydrate present in an existing formulation to affect an interaction with the tongue’s own sweetness receptors—ultimately stimulating a sweeter taste.

By making the sweet taste of a given amount of sugar go farther, not only can a formulation use less, but it can omit “artificial” substitutes. “High-intensity sweeteners tend to have very characteristic sweetness profiles that leave a lingering aftertaste, which some consumers perceive as bitter and artificial,” says Eckert.

“One of the things we’ve found from our science is that different sweeteners bind to the receptor in different ways,” Zoller says. “We’re trying to understand whether if, when these sweeteners bind to the proteins, they’re getting stuck. One of the ideas about the lingering of the sweeteners is that maybe they just stick on the receptor too well. Alternatively, maybe they’re sticking on the membrane of the cell. Those are the kind of mechanistic studies that we’re trying to do.”

Stretching the salt

Such “stickiness” might account for the bitter aftertaste of salt substitutes like potassium chloride. “Its bitterness, its metallic taste—it just doesn’t have the same effect on the taste bud,” Lutz says. “And that’s why true saltiness is so hard to replicate: Certain taste buds are a target for the compound salt. And if it doesn’t match up to that receptor, then it’s not received in the same fashion.”

Another approach, Zoller notes, is “trying to boost other flavors to try to fool people into not realizing that they’ve taken out the salt.” Witness the use of umami-enhancing ingredients like monosodium glutamate (MSG), yeast and vegetable extracts, and the nucleotides inosine monophospate (IMP) and guanosine monophosphate (GMP) in reduced-sodium foods.

One tactic is making the salt receptor more efficient. Zoller likens the sodium ion channel to a hose, “but it actually has a limit to how much sodium can pass through at a given time. We’re trying to increase the rate at which the sodium flows into the cell over a given time, so that you can still get the same signal, but reduce the amount of sodium you need to get it.” This isn’t a salt substitute: “It’s trying to make the salt we use more effective in what it does,” he says.

Researchers at FONA International Inc., Geneva, IL, are also looking at making low-sodium formulations taste saltier on their own by focusing on all its attributes. “In other words,” says Robert Sobel, Ph.D., director of technology and innovation, FONA, “we ask what happens when you put salt in your mouth. You get a watering sensation. You get a mouthfeel sensation.... It’s just a matter of understanding the physiological response of the body to salt, and seeing if you can build things around that to enhance it. How can we enhance this salt signal without adding the extra salt? What can we do to amplify that response?”

For its part, Cargill Salt’s entry into the sodium-reduction contest “isn’t just an enhancer,” Lutz says. “It’s actually a sodium-reduction system.” The system is a “limited deck” of common GRAS ingredients that allow for sodium reductions in the range of 25% to 50%, he says.

The bitter end

To enhance salty and sweet sensations, researchers are trying to block bitterness—to an extent. An appreciation for hoppy beer, strong coffee, peppery greens and high-cocoa chocolate, for example, can bring sublime pleasure. “Our approach is that, rather than block all bitterness, first we’re identifying the types of bitterness people don’t like, and then we’re picking out the bitter receptors that correspond to that,” Zoller says.

The strategy prevents the key—the bitter compound—from tripping the receptor lock. “We’re looking for a special key that doesn’t trigger the lock, but still fills the space,” Zoller explains. “It’s like putting Super Glue in the lock.” Among the many compounds that trigger bitterness, Senomyx has narrowed its search to two novel receptors, one that responds to 6-nitrosaccharin, a derivative of saccharin, and another sensitive to both 6-nitrosaccharin and denatonium, one of the most-bitter substances known.