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called TRPML3 is involved in salty taste perception. Despite having an incomplete picture of how humans sense salt, several companies are forging ahead with salt-reduction research. The task isn’t just about finding another compound that tastes salty. NaCl enhances food flavors, blocks bitterness, and contributes to specific tactile sensations in the mouth, Breslin says. What’s more, in many food products NaCl has a structural or stabilizing role and can also play a part in the cooking process, says F. Raymond Salemme, chief executive officer at New Jersey-based flavor company Redpoint Bio. “When people talk about a salt substitute, they’re talking about something that can replace the functionality of salt,” he says. For all those reasons, it’s shaping up to be nearly impossible to completely replace NaCl, Breslin says. Potassium chloride, New findings on salty taste may inspire the most common compound used in salt ways to TRICK THE TONGUE replacers, is a good substitute for much of CARMEN DRAHL, C&EN WASHINGTON NaCl’s functionality. However, it also has a bitter taste that some consumers find unpleasant. Many KCl salt substitutes still FOR THOSE WHO want sweetness withincludes trying to learn more about the bicontain some NaCl, which helps block the out the calories, there are plenty of options ology of salty taste. bitterness. available. But when it comes to imparting “The complete molecular basis of how Several companies are developing adsaltiness to food, there is pretty much one we detect salt is unknown,” says Paul A. ditives for masking that bitterness. For choice: sodium chloride. The food industry S. Breslin, an experimental instance, Redpoint has develwould like to change that. psychologist at the Monell oped bitterness blockers that O O Cutting NaCl intake in a population Chemical Senses Center, in combine the sulfonic acid tauS lowers average blood pressure and can Philadelphia. Two different rine with nucleotides such as H2N OH reduce the risk of diseases such as stroke. ion-channel proteins have been adenosine 5'-monophosphate Taurine That’s why international authorities such implicated in salt sensing on (AMP). They’re thought to as the World Health Organization advocate the basis of tests in animals, he work by reducing taste-cell population-wide measures to lower the says. But even when both of those proteins activation by bitter compounds while enamount of NaCl people consume. are put out of commission, animals can still hancing salty and umami (often described Prepared foods are a major target of saltperceive salt, which means that the saltas savory) sensations. reduction efforts because they often consensing picture scientists have in mind is tain more salt than anybody needs for their incomplete. G-protein-coupled receptors, BECAUSE IT’S TOUGH to replace NaCl, health. As a consequence, food companies which play a role in other taste pathways, researchers are also trying to make less are seeking new ways to reduce salt levels may also be involved in sensing saltiness, NaCl go a longer way by finding ways to in their products while also preserving the Breslin says. enhance salty taste. salty taste that consumers find appealing, New pieces of salt-taste biology are still Amino acids are among the simplest says Andreas Haenni, global vice president emerging. For instance, in 2008, San Diegocompounds that can do that job. At the Moof the savory segment at Swiss flavors and based flavor company Senomyx reported nell Center, Breslin and his colleagues are fragrances company Givaudan. the discovery of what its scientists believe studying the biochemistry of how the amino Companies have been working toward is the primary receptor responsible for saltacid l-arginine enhances salty taste. “My that goal for years, but finding a replacetaste perception in humans. The company guess is that arginine is affecting how long ment for NaCl in food isn’t easy. Some say has not disclosed the identity of the recepan ion channel remains open, but how it it might even be impossible. Researchers tor, which it has dubbed SNMX-29. Addidoes that isn’t clear,” Breslin says. One way are also thinking about how to make small tionally, in two recent patents, the compato find out might be to mutate amino acids amounts of NaCl taste saltier, an effort that ny provides evidence that a cation channel along the channel pore in taste cells and see SHAPELY MATTERS
Salt crystals’ shape and size influence how quickly we perceive their burst of saltiness.
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“The complete molecular basis of how we detect salt is unknown.”
how that changes arginine’s effects, he says. Companies are also actively searching for new salt enhancers. Givaudan, for one, found inspiration for a salt enhancer in bonito, a fermented fish that’s the basis of a broth commonly used in Japanese food, in England, is taking this approach. The says Robert G. Eilerman, the company’s company has demonstrated that smaller senior vice president for global science salt crystals produced by a freeze-drying and technology. The enhancer, acetyl method make for a more fast-acting and guanosine monophosphate (GMP), is therefore altered salty sensation on the related to GMP derivatives that impart tongue. “Sodium chloride must dissolve a characteristic umami sensation to the before we perceive it,” and that physical fish. Salty and umami tastes are compleprocess is intimately linked to the crystals’ mentary and can be shapes and sizes, says manipulated to miniCindy Beeren, senO mize deficiencies in sory and consumer N one area or the other, manager at LFI. NH O Eilerman says. Salt formulations N N N HO O Enhancing salt that include emulH P O HO taste through umami sions might be yet O taste may not be the another way to influonly way to go. For ence how the tongue OH OH instance, compounds senses saltiness, says Acetyl GMP that have a cooling efStuart Clegg, prinfect, such as menthyl cipal scientist in the lactate, can amplify the taste of saltiness ingredients and food innovation section of at very low concentrations, low enough LFI. Scientists at the company have studthat the compounds’ cooling effects aren’t ied salty taste perception of double emulobserved, Eilerman says. Givaudan has patsions, wherein drops of water are encased ented a series of cooling compounds that in a larger droplet of oil that’s surrounded company scientists now are optimizing for by water. “We put salt in the inside water salt enhancement, he adds. layer and sugar on the outside water layer, Manipulating salt’s physical characteror vice versa,” Clegg says. Even though the istics might be another effective way to same amount of salt was added in both enhance salty taste and therefore lower cases, taste testers reported that the emulfoods’ salt content. Leatherhead Food Insions with salt on the outside layer seemed ternational (LFI), a food research center saltier, he says.
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Currently, researchers aren’t looking for one salt-reduction strategy that is better than all the others and that can be applied to every food or beverage. “Our experience suggests that a one-size-fits-all saltreduction solution is not practical at this point,” Givaudan’s Eilerman and Haenni told C&EN in an e-mail. Each type of food presents different challenges for taste researchers, so a range of salt-reduction strategies seems to be the approach for now, they added. Beeren concurs, noting that LFI’s emulsions would likely work best in liquids such as salad dressings, whereas small salt crystals would be best suited to sprinkling atop potato chips and other snacks. No matter what the strategy, reducing salt content in foods is about helping people stay healthy, Breslin says. But population-wide salt-reduction efforts backed by public health data may not always translate into a benefit for every individual, Breslin cautions. Still, as the pressure from consumers and regulatory agencies to drive down NaCl consumption grows, researchers are bound to take heed and to continue making strides in salt-reduction strategies, Breslin says. “A lot of what food science does is to give people what they want,” he adds. ■
