One of Cargill’s biggest innovations of the past decade is getting an important test in Argentina.

A new “mid-calorie” Coca-Cola that recently launched there uses Cargill’s brand of the sugar substitute stevia, which is extracted from the leaf of a shrub and is considered a natural zero-calorie sweetener.

Cargill’s product, called Truvia, is already a hit in the packet sweetener market and has made headway in noncarbonated beverages such as juice and ready-to-drink tea.

But it has yet to crack the beverage business big time, particularly the gigantic market for carbonated drinks.

“Truvia has done very well as a tabletop sweetener, but its best days in beverages are still ahead of us, ” said John Sicher, publisher of Beverage Digest. “The industry is not going to know the real potential of stevia in carbonated soft drinks for another two or three years.”

But the industry will get a good taste of stevia’s potential with the Argentina launch of “Coca-Cola Life,” the first time the Coca-Cola Co. has used the sweetener in its flagship product.

Stevia is a relatively new ingredient, getting the green light from federal food regulators about five years ago. The zero-calorie sweetener is derived from the stevia plant, which is native to Latin America but also is grown in Asia.

Stevia’s allure is simple: It’s not an artificial sweetener, so it has a healthy halo, industry analysts say.

“It’s more in line with the values consumers are looking for today — healthy consumption,” said Larry Finkel, director of food and beverage research at

Still, a lawsuit filed in Hawaii last month against Cargill challenges the naturalness of Truvia, one of several suits against packaged-food makers over “natural” claims. Cargill said it plans to “aggressively defend the lawsuit.”

Cargill developed Truvia in a partnership with Atlanta-based Coca-Cola, and Coke today uses it in at least 45 products in 15 countries, often mixing it with other sweeteners.

PepsiCo Inc. is using stevia in the Australian version of its mid-calorie Pepsi Next. Mid-calorie sodas have a calorie level midway between zero-calorie beverages and full-calorie products.

Minnetonka-based Cargill sells Truvia directly in the packet sweetener market, a business that generates over $100 million in sales.

Truvia is the second-biggest packet sweetener with 13 percent of the market for the year ending July 14, according to IRI, a market research firm that tracks sales at conventional grocery stores. Splenda was tops with a 37 percent share.

But Truvia was the only one of the major brand-name tabletop sweeteners that showed any U.S. sales growth last year, according to IRI.

“This is not just a U.S. phenomenon,” said Matthew Jacobs, Cargill’s business development manager for Truvia. The tabletop product is now available in seven other countries, and Cargill plans to launch it in India and Brazil next year.

As an ingredient, stevia “does well in juice and tea, ” said Jonas Feliciano, an analyst at market researcher Euromonitor International. “But it’s still really in its nascent stage in beverages.” Particularly carbonated beverages.

While soda sales have been falling as obesity worries run rife, carbonated beverages still comprise one of the biggest packaged-food markets with about $21 billion in annual sales, according to market researcher Nielsen.

But carbonated beverages, particularly colas, are more complex as far as applying stevia as a sweetener, said Melanie Goulson, a principal food scientist at Cargill.

“It’s taken time for product developers to figure out how to use the ingredient,” Goulson said. “Nobody learned how to use stevia in food science school.”

A key challenge is to mask the licorice-like aftertaste that stevia can impart. Coca-Cola has made several trial runs with stevia in such lower-calorie beverages as Sprite Green and Sprite Select and Fanta Select.

Sprite Green had limited distribution and lasted from 2008 to about 2010. Sprite Select and Fanta Select were “tested in the United States,” and Coke is currently assessing whether the two sodas “support our brand and business needs, ” the company said in a written response to the Star Tribune.

In France, the company in March 2012 launched Sprite and Nestea sweetened with a combination of stevia and sugar. The drinks have 30 percent fewer calories than they had before reformulation and “are performing well, ” Coke said.

The biggie is Coca-Cola Life, which launched June 26 in Argentina. It is Coke’s first low-calorie cola sweetened with both stevia and sugar. Coca-Cola Life has 64 calories in 12 ounces, compared with standard Coke’s 140 calories. It’s meant as a complement to other Coke products, not a replacement.

“It is a unique, great-tasting option for those looking for beverages with fewer calories and is the latest example of our global commitment to offer more reduced low- and no-calorie options, ” the company said in a statement.

Why launch in Argentina? Coke said simply that there’s strong consumer demand in Argentina for a naturally sweetened beverage with fewer calories.

Feliciano of Euromonitor said Argentina is a good place to start with Coca-Cola Life. Argentina tends to be more health-conscious than much of Latin America, he said. And “especially in Latin America, consumers are very wary of artificial sweeteners.”