Taste Bud Hackers Flavours and Nutrition Research

OUTLOOK TASTE

multinational PepsiCo based in Purchase, New York,. “So when you start to talk about changing

fat in a food, you’re going to be changing all of CHRIS LOSS those things.” Which means, she says, it’s very dif- ficult to create a product that gets it all right. The food industry is hoping that an updated under- standing of taste and its underlying biology will yield flavoursome formulations that are better for us than the products on the shelves today. FISHING FOR FLAVOURS One of the major steps forward in taste science in recent decades has been the discovery and exploration of distinct taste receptors on the human tongue. Our taste buds have sepa- rate receptors for, at the very least, five basic tastes: sweet, salty, sour, bitter and umami (savoury). Of these, the receptors for sweet, bitter and umami are all members of a family of proteins called G-protein-coupled receptors (GPCRs). And because GPCRs are well understood, they provide numerous oppor- tunities for scientists looking for molecules that might trigger them. Enter Chromocell and Senomyx, based in San Diego, California. These companies have adapted high-throughput screening systems developed by the pharmaceutical industry to find potential drug candidates against GPCRs, to identify molecules that interact with taste cells. “The whole idea of using molecular biology to trick or tweak your taste buds is kind of novel for the food industry,” says Beverly Tepper, a taste researcher at Rutgers University in New Brunswick, New Jersey. The screening systems work by running a slew of molecules past a panel of taste receptors The combined hot and cold sensations of chilli and peppercorn might make a tasty substitute to salt. to see what sticks. To find new sweeteners, for instance, researchers take the protein that taste FOOD SCIENCE cells recognize as sweet and express it in a stable cell line. “Then we use this as a fishing net to run thousands of different compounds against that cell,” says Rudy Fritsch, who leads Chromocell’s Taste bud hackers flavours and nutrition research. When the instru- ments indicate that one of the molecules has stuck to a receptor — much like a key in a lock — Scientists and psychologists are trying to trick our mouths then the molecule is worth further investigation. and minds into enjoying foods that are better for us. Senomyx and Chromocell use slightly different systems and maintain slightly different research goals. Senomyx was the first company BY LAUREN GRAVITZ such products have had only modest success. to use a high-throughput screening approach to Diet soda, for example, still makes up only 30% taste research and is concentrating on synthetic ucked away in a biotechnology park in of the overall soda market. And potato crisps chemicals. Two of its sweet enhancers are already North Brunswick, New Jersey, research- fried in olestra, a fat substitute with molecules found in products being sold in test markets in ers at Chromocell are trying to make us too large to be absorbed by the gut, have fewer China, Africa, North America and elsewhere. Tchange the contents of our kitchen cupboards. calories but prevent the body from absorbing Chromocell is taking a different tack. Rather They are screening hundreds of thousands of vitamins and nutrients. Consumers complained than synthesizing potential taste enhancers in molecules to find ones that can enhance certain that these crisps caused unpleasant side effects. the lab, its researchers are putting more empha- tastes, such as sweet or salty, with the hope of People don’t derive as much pleasure from sis on using their high-throughput fishing net to concocting foods that are kind to our waistlines most low-fat, low-sodium or low-calorie foods catch natural compounds. This is an approach but still excite our palates. as they do from more indulgent chocolate with popular appeal — a growing proportion The business of creating taste enhancers and mousses and French fries. “Fat has a taste and a of the public views artificial sweeteners and fat ingredient substitutes for high-sugar, high-salt smell, it can change an item’s taste and smell, it substitutes with suspicion, so many companies and high-fat foods is decades old. Artificial has a texture and it changes texture. It’s a really are looking instead for natural products. sweeteners such as saccharin have been in wide- tricky little thing,” says Jeannine Delwiche, who Not all researchers believe that taste spread use since the mid-1900s, for example. But leads research into reducing salt, sugar and fat at enhancement needs to come from new

S14 | NATURE | VOL 486 | 21 JUNE 2012 © 2012 Macmillan Publishers Limited. All rights reserved TASTE OUTLOOK molecules isolated in a lab. Scientists in fla- yield and resilience to long-distance travel. “If vour houses (companies that develop chemi- we can make produce taste better, people will eat SWEET DISCOVEIES cals for the food and drink industry), food more of it,” says Harry Klee, a horticultural sci- 880 companies and academic institutions are also entist at the University of Florida in Gainesville. 879 / SACCHAINE 400x seeking fresh combinations of existing tastes Working with other researchers at the same Discovered by accident SWEETE and flavours, or are tweaking the properties of institute — Linda Bartoshuk, who studies taste by researchers at Johns Hopkins THAN SUGA existing ingredients, to improve a food’s health and olfaction and Charlie Sims, who runs sen- University in Maryland, saccharin profile while maintaining its appeal. They’re sory testin — Klee has developed chemical pro- became popular during sugar 890 looking for tastes and aromas that can elicit files of nearly 200 different varieties of heirloom rationing. (TRADE NAMES INCLUDE:) either physical or psychological reactions to tomato. Those with the most diverse range of Sweet’N Low, Sweet Twin help enhance flavour. sugars, acids and volatile chemicals were pre- Playing around with the shape and size of salt sented to panels of 100 consumers. These taste 93 / STEVIA 350x crystals, for instance, can help lower sodium testers noted down which ones they liked and Derived from a plant, Stevia 990 intake but maintain saltiness. Smaller crystals, how strong their preferences were, allowing the rebaudiana, that has been used or those produced in the shape of a pyramid, researchers to determine which properties of by the Guarani people of South have more surface area and pack a bigger punch the fruits confer the most (and least) desirable America for more than 1,000 to the palate. But such crystals are only effective flavours. By analysing the highest- and lowest- years. Isolated by two French for solid foods, not in soup or mixtures where ranked tomatoes, the researchers determined chemists in 1931, but not the salt is dissolved. which compounds contributed to overall taste1. approved in US until 2008. 9 0 “Scientists and flavour chemists are going to be “We could then use that data to extract the ideal Stevia, Only Sweet, SweetLeaf, Truvia searching every blade of grass and every leaf in recipe of the perfect tomato, which we’ve done,” the Amazon for something that might potenti- Klee says. “Now, we can rescue the genetics of 937 / CYCLAMATE 30x ate taste. And there just aren’t many things out what’s in the good ones and try to reincorporate Discovered by accident by there like that that have been found,” says Chris those into commercial tomatoes.” a researcher at the University of 920 Loss, a chef and culinary scientist at the Culinary Illinois, it was initially marketed Institute of America in Hyde Park, New York. SCENTS AND SENSIBILITY as an alternative sweetener for use by diabetics. A controversial Rather than looking for something that tastes During the taster panels, Klee and his col- study linked cyclamate with precisely like foods higher in sugar or salt, indus- leagues also discovered that the smell tests used cancer, and the FDA banned it try researchers are instead aiming to concoct to assess a food’s appeal had been going about in 1969. Cyclamate, as Sucaryl, 930 healthier combinations that are just as tasty. it the wrong way. It was generally assumed that is still available outside the Because the brain associates salt with savoury, a food’s odour, sniffed before it was put in the United States. umami flavourings such as monosodium gluta- mouth, was enough to determine its impact on mate (MSG) — a salt of a non-essential amino taste — the food industry has been operating acid that is found in many everyday foods, such on that assumption for decades. Indeed other 965 / ASPATAME 200x 940 as cheese and tomatoes — can enhance a food’s research has shown that when we eat something, Discovered accidentally by taste so effectively that less sodium is needed to the odours that go up to our olfactory bulb from a chemist at Searle laboratories achieve the desired effect. And adding flavours the back of the mouth are processed in a different in Illinois. Controversy over its that the brain associates with sugary items, such part of the brain to the odours taken in when we safety and allergenicity means as vanilla, can trick us into thinking a food is put our nose near something and sniff. it is one of the most studied 950 sweeter than it really is. “In previous years, people used the wrong food additives. Loss has been toying with different combina- volatiles,” Bartoshuk says. So she, Klee and Sims NutraSweet, Equal, Canderel tions that might trick the tongue into thinking used a different method. By sorting the toma- it is tasting salt. “Every taste bud is surrounded toes according to taste-tester preference, the 967 / ACESULFAME POTASSIUM by chemosensory receptors that pick up on the researchers were able to pinpoint the volatile Discovered accidentally by 960 capsaicin in peppers or the cooling effect from compounds that actually elicited a response. scientists at Hoechst in 200x menthol,” he says. Because these receptors are in They used volatiles not just to make a food smell Germany, “Ace K” is often such close proximity to the ones that sense taste, fantastic, but also to taste fantastic — endpoints blended with other sweeteners to help mask after tastes. he wondered if “you could tickle them a little bit”, not as closely linked as had been thought. “Now Sweet One and Sunett stimulating the taste receptors without the actual we know what to look for, we’ve done it in toma- 970 molecular match. toes and strawberries, and we’re going to do it in 600x Along with Szechuan cuisine expert Shirley blueberries too,” Bartoshuk says. 976 / SUCALOSE Cheng, Loss has used a combination of chilli Fundamentally, the Florida researchers are Discovered by scientists from peppers and a uniquely numbing type of working towards the same goal as their counter- sugar manufacturer Tate & Lyle and at Queen Elizabeth college Szechuan peppercorn to create an alternating parts in industry. “We’ve tried to educate people in London. Sucralose is derived 980 combination of heating (chilli) and cooling about how to eat healthier diets, but none of us from sugar: 3 chlorine atoms (peppercorn) effects. He tried to find a combi- do it,” Bartoshuk says. “I know perfectly well I replace 3 hydroxyl groups. nation of these ingredients that would allow him have no business eating spare ribs but I eat them Splenda and others to reduce a dish’s added salt. “We did a sensory anyway because I like them. And one way to get test and, while we didn’t find any increase in people to eat healthier is to make [healthy] foods 8,000x ■ 996 / NEOTAME 990 perceived saltiness, we found that people liked that they like.” Discovered by researchers it equally well,” Loss says. at Monsanto in France who The renaissance in taste enhancement is not Lauren Gravitz is a science writer based in were looking for molecules limited to processed and prepared foods. Some Los Angeles, California. similar to aspartame but scientists are trying to restore taste and nutrition without the allergenicity. to foods that have gradually had the flavour bred 1. Tieman, D. et al. Current Biol. 22, 1035–1039 Neotame is not yet marketed 2000 out of them in favour of other traits, such as high (2012).