Masking stevia

by Jeff Gelski
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Suppliers of Rebaudioside A and other stevia extracts promote their sweeteners as natural, a point of difference from other high-intensity sweeteners. Still, flavor suppliers mention a similarity — "off" or unwanted flavors. Adding ingredients to hide or "mask" any off flavors may prove crucial when formulating products sweetened with stevia extracts.

"The largest opportunity on the horizon at the moment is the challenge of masking stevia across all food and beverage categories," said Deborah Kennison, vice-president of Innovation, North America, for Symrise.

The U.S. Food and Drug Administration last December said it had no questions about two petitions regarding the safety of using Rebaudioside A in foods and beverages. The Coca-Cola Co., Atlanta, and PepsiCo, Inc., Purchase, N.Y., both announced plans for new beverage launches the same month.

Before the F.D.A. decision, stevia extracts were a niche ingredient, said Agneta Weisz, vice-president of Flavors and Technology for Comax Flavors, Melville, N.Y. Now, a majority of the flavor-masking projects at Comax involve stevia extracts.

"Now everyone is trying to get on the bandwagon," Ms. Weisz said. "Everybody wants a natural product."

Some companies want to put a product sweetened with stevia extracts on the market within three months, she said.

"The competition is very intense," Ms. Weisz said. "Everybody is trying to do a ‘me-too’ (product) right away."

Masking any unwanted flavor of the sweetener becomes an issue in these product launches. Ms. Weisz said she perceives the taste as licorice and bitter at the same time.

"I find it even more offensive than artificial sweeteners," Ms. Weisz said. "It seems to be subjective. I find it very objectionable while some people don’t find it so objectionable."

Subsets of the population may have different sensory perceptions of high-intensity sweeteners, said Mike Size, global head of Beverages for Givaudan Flavours, which has a U.S. office in Cincinnati.

"In general most people would agree that they have undesirable characteristics such as a bitter, stringent or metallic taste," he said. "There is often a lingering sweet aftertaste, which becomes unpleasant. It is important to have sensory methodology that can be utilized to identify these negative attributes effectively."

Rebaudioside A specifically has a bitter component to the sweetness level that may be overpowering when used at higher levels or with lower purity products, Mr. Size said. The time-intensity profile — the sweet perception over time, for example — is much different than would be observed in a sugar system of equal sweetness intensity.

Symrise, which has a U.S. office in Teterboro, N.J., has researched the time intensity in the off-flavor attributes from steviosides for the past two years, Ms. Kennison said.

"Significant sensory and analytical attribute identification mapping has been completed using Symrise’s patented LC Taste Sensory — Analytical technology," she said. "The major categories for the attributes of Reb A stevia are bitter, metallic, licorice, linger and astringency."

To compensate for the undesirable flavor, the amount of masking flavors used in products sweetened with stevia extracts may vary by type of product. The final concentration of flavor ingredients used when masking any kind of off flavors in food generally varies from 5 parts per million to 100 parts per million, Ms. Weisz said. For example, more masking flavors may be needed in a nutritional bar or a protein beverage.

"Proteins are notorious for absorbing flavors, including masking flavors," she said.

The amount of masking flavors for beverages sweetened with stevia extracts will depend on the type of beverage, she added. Juices need a different amount than carbonated beverages and still waters. Vitamins added to water may be bitter and will require an adjustment in masking flavors, she added.

Ms. Kennison of Symrise said the intensity of the off flavors in high-intensity sweeteners may be most apparent in beverages because of high water activity, the incremental effects of preservatives and acids.

"In other applications such as baked goods, snacks and dairy foods, the influence of fat and stabilizers can provide some mitigating effects from these aftertastes," she said.

Stevia extracts themselves may differ in taste, said Peter Milsted, executive director of sales and marketing for stevia extract supplier PureCircle, which has a U.S. office in Florham Park, N.J. Ten kinds of glycosides are found in the stevia plant, he said. PureCircle has found a way to isolate one kind of glycoside, extract it and purify it to change its taste profile, he said.

Both PureCircle and GLG LifeTech, Vancover, B.C., said their respective stevia extracts have no lingering aftertaste. GLG LifeTech said it avoids the aftertaste by extracting Rebaudioside A from impurities.

PureCircle also recently entered into an exclusive global strategic collaboration with Firmenich to accelerate the entrance of Rebaudioside A into the food and beverage industry. Firmenich, Geneva, Switzerland, has developed flavor systems for Rebaudioside A.

Another stevia extract supplier, Sunwin International Neutraceuticals, Inc., Qufu, The People’s Republic of China, has finalized an agreement with Wild Flavors, Inc., Erlanger, Ky., to sell, market and distribute Sunwin’s stevia extracts as well as to formulate proprietary natural sweetening blends for food and beverage products.

Givaudan Flavours, Dubendorf, Switzerland, has identified and applied for patents related to its discovery of the bitter taste receptor triggered by Rebaudioside A. Understanding how Rebaudioside A activates bitterness in the mouth has enabled Givaudan to develop flavor ingredients that specifically block this mechanism.

"Traditionally masking of bitterness was accomplished through trial-and-error development of flavoring compositions, which worked relatively well to cover the negative attributes," Mr. Size said. "In some cases this is still an effective approach, but there are limitations.

"In technology now practiced by Givaudan, the bitterness associated with specific non-nutritive sweeteners is traced to a specific taste receptor. With this knowledge it is possible to undertake a rational design of ingredients that neutralize the bitterness component in the sensory profile of the sweetener."

Work on giving products sweetened with stevia extracts an acceptable flavor should continue, as new stevia extracts may continue to enter the market.

McNeil Nutritionals, L.L.C., Fort Washington, Pa., on Jan. 2 filed a Generally Recognized As Safe (GRAS) petition with the F.D.A. for the use of steviol glycosides purified from Stevia rebaudiana (Bertoni) as a tabletop sweetener. Blue California, Rancho Santa Margarita, Calif., on Jan. 30 filed a GRAS petition with the F.D.A. for the use of Rebaudioside A purified from Stevia rebaudiana (Bertoni) as a general-purpose, non-nutritive sweetener in various food categories consistent with good manufacturing practice.

Masking aromas and flavors

Adding ingredients to products may bring an unwanted flavor or unwanted aroma. Listed are examples of ingredients and their flavors that may need masking:

Caffeine — Caffeinated energy products may have a bitter flavor that needs masking, said Agneta Weisz, vice-president of Flavors and Technology for Comax Flavors, Melville, N.Y. She gave an example of adding a masking flavor powder at 0.5% to a chewing gum base containing caffeine at 100 mg per stick and mint flavor.

Fiber — High-fiber foods and foods fortified with oligosaccharides are a challenge for the mitigation of the "cardboard" type notes and drying, said Deborah Kennison, vice-president of Innovation, North America, for Symrise, which has a U.S. office in Teterboro, N.J. Systems that add creaminess or mouthfeel with increased salivation effects may work. Mike Size, global head of Beverages for Givaudan Flavours, which has a U.S. office in Cincinnati, said using bran fiber may introduce small amounts of oil that release a paint-solvent-like aroma when oxidized. Givaudan Flavours may employ materials that either are ingredient-based to scavenge volatiles or flavor delivery materials that entrap the odor materials.

Omega-3 fatty acids — They may need both an aromatic ingredient and a masking flavor, Ms. Weisz said. Mint and lemon work well in covering the odor of omega-3 fatty acids from fish oil, she said.

Potassium chloride — Potassium chloride may add a characteristic lingering bitterness when used at higher levels to replace sodium chloride, Mr. Size said. Givaudan Flavours offers a series of proprietary masking agents for potassium chloride.

Soy — Soy protein may have an intense "beany" note, Mr. Size said. Givaudan Flavours has masking technology to suppress the note. Soy also has some sulfur notes that may require an aromatic ingredient, Ms. Weisz said.

Vitamins — Effective masking agents vary by vitamin. For example, B vitamins may need an aromatic ingredient, Ms. Weisz said. Vitamin C is acidic and may require a masking flavor but not an aromatic ingredient.

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