Flavor Modulation in the 21st Century

Flavor modulation sounds like an esoteric principal, but truth be told, we all have a touch of the flavor chemist in us. Even my mother betrayed an unwitting knack for the flavorist’s art in her scheme for making my siblings and me eat our vegetables: Just douse them with ketchup. As a flavor-masking technique, her “ketchup offensive” was a bit blunt, but according to Mariano Gascon, vice president, R&D, Wixon Inc., St. Francis, WI, it was not without logic.

“It makes a lot of sense,” says Gascon. “If you think about it, one of the phenomena that operates in taste modulation is taste-blocking. There are substances that have the property to block tastes, and one of them is eugenol, which is present in the clove that is used as an ingredient in ketchup. That has the property literally to just numb your receptors.”

The nutraceutical witches’ brew that’s made the kitchen an annex of the medicine cabinet presents trickier neutralization tests than mere ketchup can tackle. Fortunately, advances in flavor modulation have kept pace with the flavors being modulated.

“Companies have been working at it longer, so just by sheer concentration of effort, new technologies have been found,” says George Lutz, quality assurance/technical services manager, Cargill Salt, St. Clair, MI. “It’s opened up a whole new basket of ingredients that, to be honest, the product developer gets to play with. Just having more tools available enables them to do some unique things.”

New challenges, old solutions

“Taste masking is embedded in our culture,” says Gascon. “Mary Poppins told you to add a little sugar, and it made the medicine go down.” Similarly, chefs have long “corrected” an off-balance recipe by sprinkling in sugar, salt or vinegar.

A judicious inclusion of fat can hide a multitude of sins, too, as Kim Gray, Ph.D., senior applications scientist, Givaudan Flavors, Cincinnati, explains. “A perfect example is milk chocolate,” she says. “The cocoa itself is extremely bitter, but add some fat and sugar and you get milk chocolate, which is very pleasant.”

The off notes targeted most for masking are many. Some artificial sweeteners are notorious for “bitter, metallic, lingering” notes, says Greg Yep, vice president of global application technology, Givaudan. He cites caffeine as another bitter offender. Nutritional ingredients present the biggest headaches, with B vitamins giving off a rotten-egg taste thanks to sulfur groups, and minerals lingering on the palate as metallic or bitter. Casein comes in for criticism as bitter and soapy, and soy proteins can also taste notoriously bitter, as well as “grassy” and reminiscent of “hay,” he says. Rounding out the list, tannins and catechins, popular antioxidants, are bitter; omega-3 fatty acids can taste fishy; and the “nutraceutical market in general,” he concludes, just tastes “mainly bitter.”

But as consumers show more interest in these ingredients, “the demand for functional products has seen tremendous growth,” says Markus Eckert, vice president, technical, Mastertaste, Teterboro, NJ. “In the past, consumers seeking healthier products were willing to forgo taste in exchange for the health benefits offered by these products. Now that this trend has hit the mainstream public, food and beverage manufactures have begun dealing with a new consumer for whom taste is the top priority.”

The physiology of taste

Traditionally, a brute-force approach of drowning out off notes summed up the industry’s standard for ameliorating objectionable flavors. And, while dumping in sugar, salt, or heavy, sweetish flavors like peanut butter, vanilla and chocolate can mask some bitterness and off notes, just piling flavor atop flavor leaves a lot to be desired. For one, it’s costly. For another, it’s superficial, as an initially appealing flavor can fade in the shadow of more objectionable off notes. And, adds Gray, “in the past, many of these masking agents covered up the entire taste of the product, and not just the off notes.”

In their search for 21st-century solutions that appeal to 21st-century palates, researchers have turned to the physiology of taste for answers. “The use of receptor technology has allowed some companies to selectively screen ingredients that mask the off tastes right at the taste buds,” says Gray, “thereby tailoring the solution to the problem.” Conceding that “we’re not completely there yet,” she says, “this approach can, in the future, be fine-tuned just to block the off notes and not suppress the flavor.”

At the vanguard of the revolution are companies like Senomyx, Inc., San Diego, CA. “We’re trying to translate what people taste into the biology of taste,” says Mark Zoller, Ph.D., chief scientific officer, Senomyx. That means “understanding how taste buds work, and then understanding the proteins that mediate these tastes.” The company has discovered that taste buds are composed of mixed cells that sense the individual tastes, as opposed to the old theory of single-sensation taste buds. These cells operate in either a “lock and key” mode where the tastant binds to the receptor and triggers the neurological response signaling a specific taste, or a “channel and pore” system where ions that create sour and salty move through pores to trigger the response.

Sugar, but sweeter

In the case of sweetness, Zoller says companies want to enhance sucrose to “reduce the amount of carbohydrate you use, so it doesn’t have as many calories, while still tasting like sucrose. What our biochemical assays allow us to do is, basically, to serve as a filter. I’m only interested in the samples that actually trigger or do something to the receptor, and that’s fairly rare.” Still, the company has compiled a library of about 500,000 samples of sweetness enhancers, both synthetic and natural.