For consumers, savoriness often is all about that familiar and pleasing salty taste. This includes both the direct taste of saltiness and the indirect role salt performs in masking any bitter, metallic or astringent notes. With salt, taste intensity increases within a few hundred milliseconds and then rapidly drops off—making it a highly distinguishable and uniquely precise flavor profile. This uniqueness, combined with the multi-purpose functionality, is at the core of why sodium reduction can be such a significant formulation challenge.
The go-to sodium-reduction strategy is typically to use alternative chloride salts instead of sodium chloride (NaCl). It turns out the chloride anion can often be relatively more important functionally than the sodium cation, which is why other chloride salts are often looked to as replacers.
Since mineral salts—including ammonium chloride, calcium chloride and magnesium sulfate—deliver unwanted bitter, metallic and/or astringent tastes, the most sought-after chloride salt is potassium chloride (KCl). However, complete replacement of NaCl with equal parts KCl leads to bitter, metallic notes. Therefore, usage of KCl must be kept at approximately 30% reduction or less in order to avoid said off-flavors. This is why blends of NaCl and KCl are typically preferred.
Another angle that aids in successful mineral salt utilization is microencapsulation. This technology separates a mineral salt from its environment, which means these encapsulates can be used in foods without affecting their taste, texture or shelflife. Individual particles are covered with a protective coating, which can be a hydrogenated vegetable fat or other substance, depending on the application.
Such blends can derive from natural sources extracted from underground brine reserves 30 meters below the Atacama Desert in South America that has been discovered to offer the NaCl-KCl blend naturally. The complex contains 65% sodium and 30% potassium, thus translating to about one third less sodium compared to regular salt. In NaCl-KCl blends, it’s been shown that saltiness is suppressed at high concentrations of NaCl and KCl, but enhanced at low concentrations of the mixture.
The NaCl-KCl blending has been explored in combination with naturally brewed soy sauce. Research has shown that naturally brewed soy sauce used in frankfurters can allow for a 20% sodium chloride reduction without any negative effects on the quality of the product or its sensory attributes. However, with the addition of KCl to the naturally brewed soy sauce mixture, a 35% reduction in sodium chloride becomes feasible. These findings point to synergistic effects between NaCl and KCl. That is, the final flavor of the complex becomes more than the sum of its parts.
Salt on the Rise
Bread and rolls are the biggest contributor of sodium to American diets, making this food category the one receiving the most pressure (warranted or not) to reduce sodium. The functions of salt in bread are numerous and include: enhancing flavor; masking bitterness of other ingredients; controlling fermentation rate (by inhibiting yeast growth); reducing water activity (thereby prolonging shelflife); and improving bread texture by aiding in the formation of the gluten network.
Recently, researchers decided to focus on the wheat bread crumb itself. They were investigating whether or not the bound sodium in a wheat bread crumb is released upon mastication. The goal was to determine differences between perceived saltiness and actual salt content. Mastication simulations revealed that the interactions between sodium and wheat bread ingredients were “sufficiently weak” to allow for complete sodium extraction, implying that all the salt content in the bread crumb is available for taste perception.
It also was discovered that NaCl induces aggregation of the protein gliadin during the formation of gluten. This is, in part, because it can neutralize any excess of positively charged basic amino acids and lead to increased hydrophobic protein-protein interactions. With the heightened interest in gluten-free products, further research will be needed to understand this interplay between gluten, the bread crumb and sodium. For bakers, the implication is that it could be likely that certain grain-flour combinations are types could help reduce actual sodium levels without changing perceived levels in taste.
Other bread research has zeroed in on the manner in which the salt is distributed in and around the food matrix. Some findings suggest the magnitude of the saltiness enhancement depends on the size of the salt encapsulated in that matrix. Small encapsulates lead to small concentration gradients of salt that do not affect intensity of saltiness—and in turn, consumer liking. Large encapsulates heterogeneously spread around in the bread allow for greater salt reductions. Consumer-pleasing reductions of up to 50% were possible with such a “pulsed delivery” approach.
In a similar vein, General Mills Inc.’s Pillsbury brand recently filed a patent on a method of lowering fat that also would lower sodium in applications such as dough for biscuits, pie crusts and sweet rolls. The technology uses what the company describes as “shortening particle compositions,” or shortening “chips.” The innovation is in deliberately distributing salt unevenly in the dough product, in order to create pockets of higher salt concentration while lowering the overall salt content.
Bread and baked goods also contain sodium bicarbonate. Yet, this is actually where the majority of the sodium exists. Early-stage technological developments using hollow microsphere technology are underway to help bring down the sodium from sodium bicarbonate. Once fully developed, it is believed this technology will allow bakers to cut sodium content in breads by half.
For savory snacks in particular, the role of salt is to impart flavor to assist product texture and to act as a solid carrier of applied seasonings and flavors. Often, taste enhancers, such as monosodium glutamate (MSG) or hydrolyzed vegetable protein (HVP), are used.
Let’s Get Small
Usually, the salt that is ingested greatly exceeds the salt that is tasted. Common table salt crystals are approximately 500 microns in diameter. But, salt microspheres can be as small as 20 microns. At such sizes, the penetration of the taste bud surface of the tongue is far more efficient. Research on potato chip snacks suggests that chips with finer salt crystals offer a more rapid salt release, so consumers can get the salty flavor anticipated, but with less salt.
By maximizing surface area relative to the volume, salt microsphere technology plays into the idea of this maximum taste bud exposure. Technologists can tailor the microspheres to meet the minimum of necessary salt levels. Sodium reductions range can range from 25-50% depending on the application. This technology works best in topical or “surface salt” applications, such as potato chips, peanuts and microwave popcorn. However, it is less than ideal for broths, drinks or cured meats. On the other hand, because this technology only alters the physical form of NaCl, clean label specifications are easily attained.
Such enhancers deliver an umami flavor effect that also allows for a reduction in NaCl, without any corresponding reduction in perceived saltiness. However, there is an issue with meeting clean label criteria. Moreover, some enhancers can contain a salt level of up to 40%, meaning they must be limited in a formulation designed to limit sodium in the first place.
Soy is another such product that has been investigated for sodium-lowering capacity. The idea of soy sauce-based sodium replacement might seem counter-intuitive, because soy sauce is a traditionally high-sodium product. But recently, researchers at the University of Wisconsin, Madison, with Kikkoman USA’s R&D labs, investigated a modified form of soy sauce termed “natural flavor enhancer” (NFE). In a series of studies, it was determined that NFE, which has a higher percentage of wheat (and in some formats, yeast extract), as a typical soy sauce product made from wheat, soybeans, water and salt, yields a lower finished salt content than in a traditional soy sauce. (See, “Less Sodium, More Umami,” PF March 2014.)
In the studied NFE products, the soybeans had been fermented instead of subjected to chemical hydrolysis, increasing levels of amino acid protein components responsible for umami. The product contains no monosodium glutamate or hydrolyzed vegetable protein. Researchers were able to reduce sodium by 30-50% in savory meat applications without compromising organoleptic qualities.
Since sodium in formulations also serves as a preservative, the studies also investigated whether there was sufficient anti-spoilage action in soy sauce and NFE. The University of Wisconsin and Kikkoman team discovered that, on uncured, sliced turkey deli meat loafs, soy sauce and NFE inhibited formation of lipid oxidation byproducts called hexanes, while demonstrating superior flavor and texture across 11 days of refrigerated storage—meaning the soy and NFE can work as both flavor enhancers and salt replacers, yet appear on labels as “naturally brewed soy sauce.”
Tying into the current anti-GMO push, there are non-GMO taste enhancers rich in amino acids and nucleotides that promote development of the umami sense. For example, natural flavors derived from bacterial fermentation methods can be specifically designed to increase salty perception and enhance umami. Some are dextrose-based, and some are dairy-based.
Yeast and Amino Acids
Other methodologies for building flavor-enhancer ingredient systems include derivations from yeasts (specifically, Saccharomyces cerevisiae). Such yeast extracts are designed to enhance a “roasted” flavor, which, in turn, bolsters the umami effect. These are most appropriate for enhancement of savory notes found in products based on or using roasted poultry and meat products.
Umami, once called the “fifth flavor,” is the pleasant savory taste imparted by the combination of the amino acid glutamate; the ribonucleotides inosinate and guanylate; and small chains of amino acids known as peptides found in fungi and vegetables. Umami can increase salivation, and its enjoyment by the human palate can be credited as the drive behind the trend of foods having a combination of sweet and salty flavors.
The concept of umami was discovered back in 1908 when Kikunae Ikeda, Ph.D., isolated the glutamate component in dashi, the Japanese cooking stock. Since then, there has been extensive research on umami. One study found that naturally brewed soy sauce—a rich source of umami—allows for a sodium reduction in salad dressings, tomato soup and uncured stir-fried pork by 50, 17 and 29%, respectively.
Current studies, led by research chef Robert Danhi at Taylor’s University Asian Food Center in Kuala Lumpur, Malaysia, is investigating how naturally fermented fish sauce can lower the sodium in recipes that use chicken broth, tomato sauce or coconut curry. Because the fish sauce has many active compounds in addition to the free glutamate, including the amino acids threonine, alanine, valine, histidine and others, the resulting taste synergy has demonstrated an ability to reduce sodium in formulations at up to 25%, based on consumer testing.
“Umami in packaged foods is no different than in foodservice kitchens,” Danhi stresses. “Flavor is flavor, and umami has influenced cuisines around the globe for a very long time.” He points to the Italian examples of Parmigiano cheese, cured hams and anchovies. “These are classic umami-producing foods that influence perceived saltiness levels,” he adds.
University researchers are also well aware of umami’s power. Paul Breslin, Ph.D., professor at the Department of Nutritional Sciences of Rutgers University, New Brunswick, N.J., sees the combination of salty and umami as a “magical congruence” that creates an “additive perception of saltiness” more than sodium or glutamate alone. Breslin, who also serves at the Monell Chemical Senses Center in Philadelphia, cites pizza—with its constituent amino acids—savory bread, fermented cheese, cured meats and free glutamate in tomatoes as prime examples. Part of the inherent taste synergy involves how umami tends to last longer than any sweet, salty, sour or bitter notes that dissipate more quickly.
Chef Danhi points out that leading research in this area is looking more closely at how bacteria and fungi help break down the proteins in the flavor compounds. “This is how the flavor is released in fish sauce, soy sauce or any fermented foods,” he explains.
Blends of herbs, spices and citrus have been used for decades to enhance flavor without increasing sodium. Thyme, sage, garlic, onion and lemon peel all provide strong savory flavors in and of themselves. Yet, the power of aquatic botanicals to provide umami flavor notes and replace salt has a long tradition, too.
“Some of the best herbal and vegetal salt substitutes can be dried seaweeds, such as kelp, dulse, nori etc.,” notes Mark Blumenthal, Ph.D., founder and executive director of the American Botanical Council. “They have a salty taste, yet on the average, contain only 1-10mg sodium per gram.”
Herbal sources of saltiness and umami can be sources of more than just flavor enhancement. Adds Blumenthal, “Dried seaweeds also offer comparatively significant amounts of trace minerals, especially iodine, as well as protein and fiber; so, in addition to enhancing flavor, they have added nutritional benefit.”
The Nose Knows
Flavor is ultimately a combination of inputs from independent sensory systems that include taste, smell and, surprisingly, chemical irritation—plus other biochemical interactions. To help maintain a salty flavor perception, scientists are exploring how taste interacts with the sense of smell.
Known as “odor-induced saltiness enhancement” (OISE), aromas from sardine, cheese, soy and bacon all have been shown to enhance perceived saltiness. One study found that two aromas associated with high-salt content, sardines and Comté cheese, enhanced the perceived saltiness of a cheese taste test product compared to a carrot-derived aroma control. But, because consumers don’t want a slice of bread smelling like sardines, aroma research is focused on so-called “phantom aromas:” salty odors at or below the detection threshold. Products with low to moderate salt concentrations are more significantly enhanced by these phantom aromas than those with more salt.
In addition to phantom aromas, flavor enhancement research is also focused on adding incongruent flavors which do not change the overall flavor profile but do boost perceived saltiness. For instance, a Japanese study found that adding bonito extract—another rich source of umami—can allow for a 10% reduction of salt while improving taste in egg custards at the same time.
Within these varied and unfolding options, it’s clear the specific product matters most. From egg custards to breads to savory broths, each component—biochemistry, temperature, texture—of the food matrix and corresponding synergistic effects must be carefully and individually evaluated. By focusing on perceived sodium levels compared to actual sodium levels, developers can provide products that meets all consumer demands and product standards without sacrifice.
What Processors Should Know About Sodium and Health
Despite broad pressure to reduce salt in processed foods, compelling scientific data to justify this action has yet to be established. The most recent Institute of Medicine (IOM) review on the consequences of sodium reduction concluded there is no evidence supporting an association between sodium intake and health outcomes, and that the Dietary Guideline of 1,500mg sodium per day was inappropriate and could increase health risks.
This is because the original IOM Dietary Reference Intakes for an “adequate intake” (AI) of sodium disregarded the established standard requiring the AI to represent the consumption levels found in healthy populations.
The current effort to reduce salt in processed foods is not a response to broad consumer demand; it is the acquiescence to government-leveraged, anti-industry activist pressure. Experience also shows that scientific evidence is a far less-fickle guide for costly product development efforts than is activist opinion. The history of trans fats is an excellent example of this. Consumer activists and government criticized the food industry for the use of animal fats in foods and aggressively promoted the use of trans fats. Three decades later, the very same activist groups and government castigated the industry for the use of trans fats.
Not a single healthy population in the world consumes as little as 2,300mg, much less the AI of 1,500mg sodium per day. World populations consume from 2,700-4,800mg/day, averaging around 3,700mg, regardless of location, culture or economic circumstance. Predictably, the best health outcomes also fall in the same range, because consumption of sodium below that range causes plasma renin and aldosterone levels to climb sharply, thus increasing the risks for a broad range of negative health outcomes. So, while establishment opinion aggressively promotes salt reduction, the latest scientific evidence flatly rejects it.
—Morton Satin, Vice President, Science and Research, at the Salt Institute (www.saltinstitute.org)
Worth Its Salt
The human body needs sodium to live. All-natural, unrefined salts are composed of the same trace minerals found in the body. Naturally harvested, unrefined salt reflects its environment as much as wine, cheese or coffee beans. Sea salts and mineral salts, in general, are less bitter than refined salts. Because of the full flavor without the bitterness, it’s just natural to use less when cooking, making them an excellent source for reducing overall sodium content.
Depending on where and how a salt is harvested affects its taste, texture, aroma and color. Tampering with its inherent mineral composition is a game-changer, yet understanding which salts to use and the many ways to mindfully salt a dish will promote salt in a whole new—and positive—light.
For example, crunchy, but quick-dissolving flake salts are best for baking and finishing. Flake salts (especially pyramid crystal flakes) have a large surface area and, therefore, provide a burst of flavor that quickly dissipates: thus nicely introducing the flavor of a dish without overpowering it. Larger, coarse crystals, such as in Himalayan and Hawaiian salts, are ideal for roasting. They help retain the meat’s juices and moisture—and, thus, flavor—throughout the cooking process. The longer a grain crystalizes, the denser it becomes.
The famous French salt, fleur de sel, is especially unique for how it is formed and harvested. A dry wind in the night makes fragile, young crystals form on the surface of salt ponds. This is gently scraped from the surface with wood rakes early in the morning. The result is a fluffy, moisture- and mineral-rich salt often described as smelling of lavender. It has long been considered the crème de la crème of salt and is ideal for finishing dishes, especially delicate ones, such as roast vegetables.
Beside the salinity, aroma or even the color salt adds to a recipe, the mineral composition affects each salt differently, as well. Traditional recipes often call for the salt of the region, as it’s the only way to call it authentic. Kahlua Pig just isn’t Kahlua Pig without Hawaiian sea salt. And, the French would turn away from a finishing salt that wasn’t a French gris (gray) or fleur de sel.
Increasing in popularity are flavored and smoked sea salts. Fusion-flavored salts are the simple infusion of sea salt with all-natural ingredients, such as herbs or spices. Spicy varieties (such as those using habanero peppers and even sriracha) can rival a hot sauce, while savory infusions using ingredients like black truffle, rosemary or espresso add their own subtle notes to formulations.
Smoked salts are rapidly becoming a staple in many consumer pantries. Smoked salts are cold-smoked for 48 hours over specific woods to impart a smoky, campfire-cooked flavor to dishes. Each wood variety imparts a different flavor. For example, alder wood tends to be a sweeter wood than, say, apple wood, which is a very savory wood. Pacific Northwest Native Americans traditionally smoked salmon using only alder wood, as they preferred the resulting flavor balance of sweet and smoky.
—Naomi Novotny, Owner and President, SaltWorks Inc. (www.seasalt.com)