Reducing Sodium, A Matter of Taste
In the fall of 2006, industry newsletters reported on yet another study investigating the impact of salt reduction on hypertension. This time the research, published in the American Heart Association's September issue of Hypertension, indicated that a clinical trial meta-analysis showed that modest reductions in children’s salt intake significantly reduced blood pressure. The research reviewers were J. Feng He and Graham MacGregor. MacGregor chairs two organizations pressuring food companies to reduce the sodium content of their products. Their voices join many others, such the American Medical Association, calling for decreased sodium levels in restaurant fare and packaged foods.
Although the strength of the sodium-hypertension link is still debated (for example, inadequate intakes of potassium, calcium and magnesium may also play a role in hypertension), few would argue that high blood pressure, a condition increasing risks of cardiovascular and certain other diseases, is not cause for concern. Almost one third of U.S. adults, or more than 65 million Americans, have hypertension.
According to “What We Eat in America,” a report based on the National Health and Nutrition Examination Survey (NHANES) compiled in 2001-02, the average American consumes 3,292mg sodium. Both the 2005 U.S. Dietary Guidelines for Americans and the NIH’s National Heart, Lung and Blood Institute’s April 2006 revised guidelines call for a maximum daily intake of 2,300mg sodium. The Institute of Medicine notes a 1,500mg level can further lower blood pressure.
Some estimate that 75% to 80% of Americans’ sodium intake comes from processed and restaurant foods. Food formulators are looking for options to reduce sodium-containing additives including salt or sodium chloride (NaCl), which is roughly 40% sodium by weight.
Leavening OptionsSodium can be incorporated into prepared foods in unexpected ways. For example, depending upon the application, chemical leavening agents in baked goods can be a significant source. Leavening occurs when an acid combines with a base to produce carbon dioxide. Sodium is a common component in both acidic and basic leavening agents. If the base used is sodium bicarbonate, sodium-free alternatives such as potassium bicarbonate or possibly ammonium bicarbonate should be considered.
Bakers need to control the rate of carbon dioxide formation in their products in order to achieve proper baked volume and texture. Encapsulating ingredients is one tactic to control their release rate, but this may increase the level of undesirable high-melting fats such as trans or saturated fats in a product. “It is very difficult to have controlled release leavening without a sodium-based acid,” says Barbara Heidolph, market development manager at a leavening supplier. When agents like sodium acid pyrophosphate (SAPP) are replaced with traditional calcium phosphates, leavening can be either too fast, such as with monocalcium phosphate, or too slow, such as with dicalcium phosphate. In either case, the product may fail to reach optimal volume, since gas released prematurely is lost during the mixing stage, and gas released belatedly cannot properly expand product that has already set.
Since a sodium-free leavening agent with perfectly timed gas release has not been available, manufacturers have had to compromise, says Heidolph. However, a novel calcium acid pyrophosphate (CAPP) leavening agent is now available that can reduce sodium by up to 26%, while providing controlled release. There are other calcium phosphates, but these alternatives involve a combination of CAPP and MCP that has an early reaction. “Not only is sodium reduced but calcium, which has heart healthy benefits, is added,” she notes.
BeveragesIn some beverages, a primary source of sodium includes microbial preservatives such as sodium benzoate along with preservative synergists like the sodium polyphosphates or sodium hexametaphosphate (SHMP). Several strategies can be employed to reduce sodium levels in beverage products employing such preservative systems, offers Heidolph.
First, sodium benzoate levels can sometimes be reduced up to 50% if a polyphosphate is added. Typical use levels for the preservatives are about 1,000ppm. Another strategy is to replace sodium benzoate with potassium sorbate. If higher levels of potassium sorbate cause off flavors, the sorbate can also be reduced up to 50% by adding polyphosphate. Of course, microbial shelflife tests should confirm the efficiency of the new systems since organic acid preservatives vary in effectiveness depending on factors like the microbial spoilage organisms of concern, storage conditions and other components in the food’s matrix.
Although the traditional polyphosphates used are sodium-based themselves, they add less sodium than the sodium benzoate they replace. However, a new mixed cation (sodium and potassium) polyphosphate is available that replaces the sodium version and allows for further sodium reduction, says Heidolph. The ingredient, also known as sodium potassium hexametaphosphate (SKMP), replaces some 70% of the sodium with potassium and results in as much as a 72% reduction in overall sodium contribution. Additionally, SKMP can provide protein and calcium stabilization. Thus, processors can achieve a significant sodium reduction in applications where polyphosphates are used to stabilize protein such as dairy- and soy-based beverages, smoothies and cheese sauces.
Counting on ChloridesNaCl “potentiates” flavor. It helps reduce bitterness and makes certain other flavors more pronounced. When NaCl is reduced, other ingredients can help compensate for its taste contribution.
Potassium chloride (KCl) is often used to wholly or partially replace NaCl. However, KCl can have a bitter, metallic taste. Thus, manufacturers may use it in combination with ingredients such as spice, yeast extracts and other flavor enhancers.
“Salt [NaCl] is unique. It is a hard taste to match,” says Dave Adams, president of a company that creates solutions for sodium-reduced foods. One of the more unique characteristics of NaCl is an initial sweet taste that many sodium replacers have difficulty mimicking. A product’s taste profile noticeably changes when that initial sweet impact is missing, he notes.
Compensating for NaCl’s sweet contribution is one tactic in formulating reduced-salt foods. This can also assist with the issue of KCl’s bitter taste. An analogy occurs with soft drink formulations in which sweeteners are used to reduce the perception of bitterness from caffeine. KCl is not as bitter as many additives, but the same concept that works in soft drinks will work when trying to reduce bitterness in savory applications, says Gary Czosek, a manager of meat and savory applications at a flavor supplier. Czosek suggest that “toners” may be useful in low-sodium formulation. Toners, which are flavorings used to mimic the flavor notes of high-quality vinegars and “tone down” vinegar astringency, can provide a “sweetness” that reduces KCl’s bitterness.
Formulation difficulty varies depending upon application. For example, formulating reduced-salt soups or sauces in which ingredients are incorporated into the food matrix may be easier than formulating potato or tortilla chips in which topical salt replacers are used. In soups and sauces, other food components more easily hide the metallic note of KCl, whereas it is difficult to disguise the immediate high-impact taste of KCl in topical applications, points out Adams.
Tasty Molecular MorselsFlavor enhancers, either individually or in combination for a synergistic effect, can help replace the “flavor-potentiating” ability of NaCl. In addition to true meat extracts, yeast-derived ingredients, monosodium glutamate (MSG), hydrolyzed vegetable or plant protein (HVP or HPP), and 5’ nucleotides (e.g., disodium inosinate and disodium guanylate) long have been commercially available as taste potentiators.
Yeast-based ingredients provide a umami taste and boost overall flavor, including brown notes and salt perception. Dried yeast, yeast autolysates, hydrolysates and plasmolysates (as well as yeast extracts) are forms of inactive yeast products. Torula yeast most often is the source of inactive dried yeast and appears as “torula yeast” on ingredient labels. The other yeast-derived flavor enhancers are manufactured primarily from Saccharomyces species such as various bakers’ and brewers’ yeasts.
Autolyzed yeast flavor enhancers are created when the yeast’s own enzymes are used to break down cells under carefully controlled conditions. The entire cell contents comprise the resulting autolysates. This includes flavor-enhancing compounds such as peptides, amino acids (including glutamic acid), monosaccharides, nucleotides, various salts and also cell walls. Autolyzed yeast ingredients are turbid and generally used at a 0.5% to 1.0% level in a formula.
When autolysates are centrifuged to remove cell walls, water-soluble yeast extracts are obtained. The extracts are virtually clear and generally have cleaner flavors than autolysates. During processing, extracts are concentrated to pastes. Further drying and often proprietary heating processes (e.g., toasting parameters) create a range of ingredients that can be used to enhance different flavor profiles.
For example, “Autolyzed bakers’ yeast extracts are light in color and flavor and are best suited for salt replacement in chicken or poultry,” says Adams. Although bakers’ yeast is most commonly used, brewers’ yeast can create a cheesy profile. “Utilizing brewers’ yeast extracts gives a heavy, aged cheddar profile and aftertaste,” explains Adams. Oven-dried yeast extracts provide nice, rich, brown notes. They are best used to achieve a hardy dark flavor, he adds.
Yeast cells can also be broken down (hydrolyzed) using acids or external enzymes to create hydrolysates, or by osmotic pressure in which yeast cells are suspended in high salt solutions (plasmolysis) to create plasmolysates. Overall, depending on yeast strain selection and processing steps, the ingredients provided by manufacturers vary in sodium content, flavor profile, taste attributes and levels of key components.
The nucleic acids RNA and DNA are made up of nucleotides, two of which are IMP and GMP. Adams notes that these nucleotides are roughly 20 times more potent than MSG. Thus, technologies that increase nucleic acid levels in yeast strains enhance the flavor-enhancing quality of yeast extracts made from them. Advances in enzyme technology and proprietary concentration steps also have brought about higher yields of GMP and IMP, he adds.
Other TacticsFermented proteins may suppress bitterness, agrees Czosek. However, such ingredients often can be of issue when there are allergen, vegetarian or kosher restrictions. Flavor enhancers that do not contain yeast, MSG or HVP can be created using Maillard reaction technologies. Such ingredients are often cost effective and appease consumers who are interested in a cleaner label.
Herbs and seasonings can also overcome the bland and bitter tastes associated with reduced-sodium foods. “Most people are accustomed to the taste of salt, but they overuse it because the foods they eat are rather bland,” explains Czosek.
When spicy seasonings are used to reduce salt, the consumer’s palate is redirected to concentrate on those ingredients’ impact instead of salt, says Czosek. Achieving the appropriate level of lingering is the key to seasoning with spicy ingredients. For example, a product’s heat should be great enough that it contributes to a desire to continue eating, but not so great that the consumer “calls it quits” after a couple of bites. Layering flavors with the heat of spicy peppers and then cooling them with lime is another way to make up for the loss of salt, he says.
Encapsulated ingredients can be used to release various flavors at different times. For example, a beefy flavor note could be created to release after a smoky or roasted note. “Aroma can trick the palate into believing that a strong smell is equivalent to a strong taste,” offers Czosek.
Sodium reduction is not simple, but since it is not possible to trick the body from experiencing hypertension, fooling the palate to be satisfied with less salt is the only alternative.
Website Resources:www.nhlbi.nih.gov/ — To access the Dietary Approaches to Stop Hypertension (DASH) eating plan
www.ama-assn.org/ — For news relating to AMA’s fight to remove salt’s GRAS status
www.bellff.com — For information about suppressors, toners and enhancers
www.savourysystems.com — For more information about yeast extracts
www.icl-perfproductslp.com — Information on no-sodium leavening agents and reduced sodium polyphosphates for protein and mineral stabilization and shelflife enhancement of beverages