Bitterness is in. Lately customers at Studio, a French-Mediterranean restaurant in Laguna Beach, California, have been ordering more frisee salads, endive, dark chocolate gateaux and strong coffee, says executive chef James Boyce. "Years ago, we didn't see a lot of that," he says. The surge in popularity, though, actually makes the chef's task of juggling flavors more difficult. Bitter flavors are hard to control. Raspberries and blackberries picked before their prime--and just about any dessert made from citrus fruits, for that matter--need tempering doses of sugar or honey. The red-wine reduction sauce atop Boyce's pancetta-wrapped New Zealand venison might taste too sharp without the dish's rich juices. Each teaspoon, dollop or pinch, though, contributes to obesity, heart disease, tooth decay, high blood pressure and other food-related ailments. What if there were some way of manipulating the sensation of bitterness without having to pile on a bunch of other flavors and unhealthy ingredients? "It would go against everything I've been trained to do," says Boyce. But, he admits reluctantly, he might consider it.
Professional chefs and other food "flavorists" are always on the hunt for the Next New Taste. Now molecular biologists may have beaten them to it. One of the byproducts of the decoding of the human genome is a better understanding of the biochemistry of taste. For the first time researchers have been able to trace the link between genes that control taste and what happens when a bearnaise sauce dissolves on the tongue.
Scientists are now perfecting a new class of food additives that can trick the tongue into tasting flavors that aren't there, or ignoring ones that are. When these chemicals hit the market in a few years, they may cause the biggest change in the way food is prepared since the invention of the spice grinder. Diet soda would taste like regular soda, saltaholics could cut back on the sodium and never know the difference, and children would eat their broccoli without a fuss. "In terms of understanding the molecules involved in detecting specific tastes, progress in the past three or four years has been stupendous," says Gary Beauchamp, director of the Monell Chemical Senses Center in Philadelphia. Researchers have largely solved how the tongue tastes.
The first fruits of this new food science are sitting in clear plastic souffle cups atop a round table in Beverly Tepper's test kitchen. She and a NEWSWEEK reporter are about to sample, for the first time, a substance that looks just like confectioners' sugar but has no calories. A nutritionist at Rutgers University's Sensory Evaluation Lab in New Jersey, Tepper has organized taste tests on everything from soy milk to peanut snacks, but the "bitter blocker" she's trying out today is brand new. We cleanse our palates with water and reach for cups of white grapefruit juice. It has that lingering, bitter aftertaste that steers so many buyers toward the OJ. The second cup of grapefruit juice, though, has a few drops of the bitter blocker, which reveals a burst of previously hidden flavor. With the bitterness gone, the grapefruit's natural tartness and sweetness come through. "It's clearly grapefruit juice," says Tepper, "but this takes the edge off."
The bitter blocker in Tepper's kitchen is being developed by Linguagen, a small start-up cofounded by Robert Margolskee, a neuroscientist at New York's Mount Sinai School of Medicine. It's a substance that occurs naturally in meat, fish and milk (which is one reason milk imparts a milder taste to coffee). Margolskee's lab came upon the molecule while screening hundreds of compounds for bitter-blocking activity--a process that used to require months of human taste panels but can now be completed in a matter of hours. Labs clone human taste cells and proteins, combine them in a dish with something bitter (usually caffeine or quinine) and add various molecules to see which prevents bitter receptors normally found on the tongue from firing.
Bitter blockers bring a fundamentally new biochemistry to flavor enhancement. Scientists have long known that the human tongue detects four basic flavors--bitter, sweet, sour and salty--and in recent years they've confirmed a fifth, umami, a term derived from the Japanese word for "deliciousness" and coined by a Tokyo chemistry professor 100 years ago. The flavor is akin to chicken soup or the Japanese soup-base dashi. Scientists believe that each receptor is specific to just one type of compound (i.e., bitter compounds bind to bitter receptors and sweet ones to sweet), although there appear to be more receptors for bitter--about 30--than for any other flavor. That's because detecting poisons, which are usually bitter, before they are ingested can be a matter of life or death.
The traditional strategy for countering bitterness--adding salt and sugar--doesn't really stop the bitter taste at all. Instead, it distracts the brain from the bitterness by overwhelming it with other flavors. Bitter blockers, by contrast, do just what their name implies: they block the palate from giving reliable information to the brain. In some cases, the molecules fit hand in glove into particular receptors, preventing bitter-flavor molecules from doing likewise. In other cases, they intercept the communication between taste cells and the nerve endings that send signals to the brain.
But is it wise to get too good at tricking ourselves into ignoring harsh flavors? The link to poisons, after all, is a very good evolutionary justification for our tongue's sensitivity. "There's a rough correlation between how bitter something is and how much you probably shouldn't eat it," says Beauchamp. The reason small children don't like bitter-tasting greens, like broccoli and brussels sprouts, is that they have more trouble than adults digesting them. And while scientists at Linguagen say bitter blockers have the potential to make processed food more healthful--salt is added to canned soup, for instance, because the process of pasteurization leaves behind bitter flavors--nutritionists are skeptical. "This is just another cosmetic for foods," says Marion Nestle, chair of nutrition and food studies at New York University. Fixing the taste of processed food, she says, is the last thing we need to do.
Scientists at Linguagen and its larger competitor, Senomyx, based in La Jolla, California, counter that their technology is far from Frankensteinian. While it's targeted at manufacturers, not home chefs, it's not so powerful as to be able to make sludge taste like an ice-cream sundae. Because their research targets the tongue, with its five basic senses, and not the nose--which can distinguish more than 500 aromas--the so-called field of molecular flavor modification will be able to impart mostly subtle changes. Moreover, says Beauchamp, "in the U.S. food system it's unlikely that there's anything that will have so many bitter toxins it could actually hurt you." Arthur Caplan, chair of the Department of Medical Ethics at the University of Pennsylvania and a fellow of the World Economic Forum, says flavor technology is preferable to the genetic modification of foods. "This is aimed at the consumer instead of the farmer," he says. "Most of the applications we've seen for biotechnology have involved making foods easier to grow. From the consumer's point of view, there's not much added value in eating genetically or biotechnologically modified foods. There's nothing in it for them. But if you can make healthy food more attractive and tastier, that's great."
Other new flavorings are in the pipeline. Linguagen and Senomyx are developing so-called sweetness potentiators. They work by allowing sugars to bind more tightly to receptors. Shawn Marcell, Linguagen's CEO, says manufacturers would be able to use one fifth to one tenth the amount of sugar they do now, without sacrificing sweetness or taste. Senomyx has signed joint-research agreements with Coca-Cola, Nestle and Campbell's Soup, and is working on ways of ampli-fying our ability to detect salt and umami, thus potentially improving the flavor of meat, fish and low-sodium dishes. (Linguagen wouldn't disclose its partnerships.) But we're still at least a year away from seeing these compounds in the food we eat. "In my opinion, it's one of the hottest technologies that has come to the food industry," says Jozef Kokini, chair of the Food Science department at Rutgers. Boyce, the Laguna Beach chef, has a tougher challenge for the scientists: "If you could figure out how to fix something you just burnt the heck out of," he says, "you'd solve a lot of chefs' problems." Perhaps that should be next on the list.