|Stevia rebaudiana flowers|
Stevia rebaudiana is a plant species in the genus Stevia of the sunflower family (Asteraceae), commonly known as sweetleaf, sweet leaf, sugarleaf, which is widely grown for its sweet leaves, the source of sweetener products known as stevia. As a sweetener and sugar substitute, stevia's taste has a slower onset and longer duration than that of sugar, and some of its extracts may have a bitter or licorice-like aftertaste at high concentrations.
With its steviol glycoside extracts having up to 300 times the sweetness of sugar, stevia has attracted attention with the rise in demand for low-carbohydrate, low-sugar sweeteners. Because stevia has a negligible effect on blood glucose it is attractive to people on carbohydrate-controlled diets.
The availability of stevia varies from country to country. In a few countries, it has been available as a sweetener for decades or centuries; for example, it has been widely used for decades as a sweetener in Japan. In some countries health concerns and political controversies have limited its availability; for example, the United States banned stevia in the early 1990s unless labeled as a dietary supplement, but since 2008 it has accepted several specific glycoside extracts as being generally recognized as safe for use as food additives. Over the years, the number of countries in which stevia is available as a sweetener has been increasing. In 2011, stevia was approved for use in the EU. The leaves can be eaten fresh, or put in teas and foods.
History and use
The plant has a long history of ethnomedical use by the Guaraní, having been used extensively by them for more than 1,500 years. The leaves have been traditionally used for hundreds of years in both Brazil and Paraguay to sweeten local teas and medicines, and as a "sweet treat".
In 1899 Swiss botanist Moisés Santiago Bertoni, while conducting research in eastern Paraguay, first described the plant and the sweet taste in detail. Only limited research was conducted on the topic until in 1931 two French chemists isolated the glycosides that give stevia its sweet taste. These compounds, stevioside and rebaudioside, are 250–300 times as sweet as sucrose and are heat-stable, pH-stable, and not fermentable.
The exact structure of the aglycone and the glycoside was published in 1955.
In the early 1970s, sweeteners such as cyclamate and saccharin were suspected of being carcinogens. Consequently, Japan began cultivating Stevia rebaudiana as an alternative. The plant's leaves, as well as the aqueous extract of the leaves and purified steviosides, were developed as sweeteners. The first commercial stevia sweetener in Japan was produced by the Japanese firm Morita Kagaku Kogyo Co., Ltd. in 1971. The Japanese have been using stevia in food products and soft drinks, (including Coca Cola), and for table use. Japan currently consumes more stevia than any other country, with stevia accounting for 40% of the sweetener market.
Today, Stevia rebaudiana is cultivated and used to sweeten food elsewhere in East Asia including China (since 1984), Korea, Taiwan, Thailand, and Malaysia. It can also be found in Saint Kitts and Nevis, Brazil, Colombia, Peru, Paraguay, Uruguay, and Israel. China is the world's largest exporter of stevioside.
For centuries, the Guaraní peoples of Paraguay used Stevia rebaudiana, which they called ka'a he'ê ("sweet herb"), as a sweetener in yerba mate and other foods, and as a medicinal agent.
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