Similar channels exist for compounds like potassium chloride— salt’s most common substitute— but the sensory signals it sends just aren’t the same. “Potassium chloride is very bitter compared to sodium, and it enhances metallic notes,” Eckert explains. Use it to replace salt in a chicken broth, he says, “and it would make that profile lean more towards an almost red-meaty type just by changing the minerals there.”
That’s one of many exceptional sensory qualities that make salt’s seamless substitution one of the most difficult magic tricks to pull off. “Salt is complicated in how it performs, or tastes, in our mouths,” says Kim Gray, senior applications scientist, Givaudan, Cincinnati. “There is the up-front salty burst, followed by mouthfeel or fullness, finished off by other attributes around salt,” she says. “Full-salt products have a fairly rounded taste to them and, after the initial burst, the salty character lasts a long, but pleasant, time. This is why replacing salt with a single ingredient is so difficult, because there is no one ingredient that does all of this.”
Salt can potentiate sweetness. “At lower levels, some people actually perceive salt also as sweet,” Eckert says. “So, if you’re looking at high-sugar solutions beyond a level of around 30%-plus, 0.2% of salt can almost replace 2% of sugar, in combination with sweeteners.”
George Lutz, technical services manager, quality assurance, Cargill Salt, St. Clair, MI, adds: “Salt has a wonderful ability to improve the perception of flavor in a variety of foods. For example, the properties of salt produce a chemical reaction that makes a fresh tomato taste even better. The salt neutralizes the acids of the tomato and sweetens the taste.”
Or, as Novotny says, “it’s like how you can put salt on a grapefruit and that makes it taste sweeter.” Recreating salt’s power both to amplify and to balance flavors confounds formulators seeking to reduce and replace it.
Salt is also the quintessential salivation agent. “That’s why it’s used in a lot of snacks and appetizers,” Eckert points out, “because when they’re served, they trigger your appetite for the main course.” One other quality people don’t often attribute to salt is its effect on texture and mouthfeel. “It provides solids, of course,” he says. “So, if you’re looking at low-sodium formulation and you’re taking out a couple of grams, you’ve got to replace them with something.” Typically, another crystalline material will do but, without it, “you’re definitely losing mouthfeel and you’re losing texture, as well.”
Tough customers
We miss salt’s texture most glaringly on applications where it appears as a topical seasoning: pretzels, crackers, nut mixes and chips. As Kathi Sparks, flavorist, Wild Flavors, Inc., Erlanger, KY, points out, “The first component off a chip that hits the tongue is the outside salt.” So whatever you use in its stead had better be good.
“Topical applications result in the direct dissolution of the material on the tongue,” Lutz says. So, a suitable substitute would have to undergo the same immediate dissolution while also cranking up the salivary juices as salt does. Furthermore, while internal uses can count on the product’s full seasoning matrix to distract the palate from the missing sodium, surface salt often flies solo. “There is little to no masking of any off tastes by the nose, because salt is one of the few materials that can be detected solely by the tongue,” he adds.
Physical limitations also hamper topical salt replacement. “The seasoning on a snack has to be dosed at a certain rate,” Eckert explains, “so there has to be a certain quantity that you have to apply to get even distribution on your snack.” And those dose rates are fairly high, he adds— running anywhere from 3% to 8%. In the past, “a significant amount of that was salt,” he says. But now that we’re cutting back, “you’ve definitely got to look at other bulk ingredients to make up for that.”