What are stevia and steviol glycosides?

Steviol glycosides are sweet substances found in the Stevia rebaudiana plant (usually called stevia). Twelve steviol glycosides are approved as sweeteners in the EU. They are not energizing (0 kcal), do not raise blood sugar (GI 0) and are also of natural origin. This makes them an excellent choice for reducing sugar in foods and beverages. Here you can learn more about stevia and steviol glycosides. You also get tips on more reading.

Steviol gly­co­sides are the sweet sub­stances extract­ed from the plant ste­via, used as a calo­rie-free sweet­en­er. In this arti­cle, we answer com­mon ques­tions about ste­via and ste­vi­ol glycosides.

What is stevia?

Stevia is a genus of 240 dif­fer­ent species of plants in the sub­trop­i­cal and trop­i­cal parts of South America and west­ern North America. But in prac­tice, there is only one specie referred to – Stevia rebau­di­ana – which in English is called can­dyleaf, sweet­leaf, or sug­ar­leaf.

As the name implies, the leaves of the plant have a sweet taste. The sweet­ness comes from ste­vi­ol gly­co­sides found in the leaves of ste­via. Steviol gly­co­sides are 50–450 times sweet­er than reg­u­lar sugar.

Stevia has been used as a sweet­en­er by the indige­nous peo­ple of Paraguay and cen­tral South America for hun­dreds of years. Nowadays, ste­via is grown for com­mer­cial extrac­tion of ste­vi­ol gly­co­sides. Cultivations exist in cen­tral South America, China and Southeast Asia, and the USA. Farming is also done in some places in Europe.

What are steviol glycosides?

Steviol gly­co­sides are the col­lec­tive name of the sweet sub­stances found nat­u­ral­ly in the plant Stevia rebau­di­ana — which com­mon­ly is called ste­via.

There are about forty dif­fer­ent ste­vi­ol gly­co­sides. Twelve of them are approved as sweet­en­ers in the EU. Of these twelve, three are main­ly encoun­tered in practice:

  • Stevioside is the ste­vi­ol gly­co­side most com­mon­ly found in ste­via leaves (5–10%). It has a bit­ter taste and an after­taste rem­i­nis­cent of liquorice. Therefore, it is not used as much as when ste­via was approved in 2011. Instead, the focus has been shift­ed to two more tasty ste­vi­ol glycosides.
  • Rebaudiana A (which is often abbre­vi­at­ed as Reb A) is found in a small­er pro­por­tion of ste­via leaves (2–4%), but is the most com­mon­ly used ste­vi­ol gly­co­side in food and bev­er­ages. Compared with ste­vio­side, it has much less bit­ter off-taste and much less of an after­taste of liquorice.
  • Rebaudiana M (often abbre­vi­at­ed as Reb M) has no bit­ter­ness at all and no liquorice-like after­taste. Its taste pro­file is almost iden­ti­cal to sug­ar. It makes it ide­al for replac­ing the sweet­ness of the sug­ar. But the pro­por­tion of Reb M in ste­via leaves is tiny (< 0.1%), which makes Reb M more expen­sive than Reb A.

All ste­vi­ol gly­co­sides con­sist of the sub­stance ste­vi­ol to which glu­cose mol­e­cules are linked with so-called gly­co­sidic bonds.

The only thing that sep­a­rates dif­fer­ent ste­vi­ol gly­co­sides is how many glu­cose mol­e­cules are linked and where they are locat­ed. For exam­ple, ste­vio­side is linked by three glu­cose moi­eties, and Reb A by four.

Reb M has a total of six glu­cose moi­eties. The high num­ber of glu­cose moi­eties is part of the expla­na­tion for Reb M’s good taste; stud­ies indi­cate that more glu­cose units pro­duce more sweet­ness and less bitterness.

Reb A on the left con­sists of ste­vi­ol linked to four glu­cose moi­eties. Reb M on the right con­sists of ste­vi­ol linked to six glu­cose moi­eties. Source: PubChem.

What makes steviol glycosides good as sweeteners?

There are two rea­sons why ste­vi­ol gly­co­sides are excel­lent sweeteners.

First and fore­most, they sup­ply no ener­gy (0 kcal) and do not raise blood sug­ar (GI 0).

Also, ste­vi­ol gly­co­sides are found in nature, and they are extract­ed from ste­via in much the same way that sug­ar is extract­ed from sug­ar beets and canes. Consequently, many con­sumers see them as a more nat­ur­al alter­na­tive than syn­thet­i­cal­ly pro­duced sweet­en­ers such as aspar­tame, ace­sul­fame K and sucralose.

How are steviol glycosides extracted?

Steviol gly­co­sides are extract­ed from the plant ste­via in a way that is sim­i­lar to how sug­ar is extract­ed from sug­ar beets and canes.

The plant is dried, and the leaves are sep­a­rat­ed from the stems. These are then soaked in hot water. The infu­sion con­tains ste­vi­ol gly­co­sides, but also plant pig­ment, gelati­nous sub­stances, oil, wax, pro­teins as well as tan­nic acid and oth­er polyphe­nols which are sep­a­rat­ed through dif­fer­ent filters.

The puri­fied infu­sion is poured through ion exchange resin which cap­tures ste­vi­ol gly­co­sides but lets the water through. Ion exchange resin is a porous mate­r­i­al with an elec­tri­cal­ly charged sur­face that cap­tures ste­vi­ol gly­co­sides. It’s the same tech­nol­o­gy used in water treat­ment plants. To remove the ste­vi­ol gly­co­sides from the porous mate­r­i­al, it is rinsed with pure alcohol.

The alco­hol is removed in a mem­brane fil­ter and through dis­til­la­tion. What remains is a sweet syrup from which most of the remain­ing flu­id is squeezed out before the left­overs are dried to become ste­vi­ol gly­co­side crystals.

The crys­tals are then dis­solved in alco­hol again, and the process is repeat­ed until you get the desired puri­ty before they are dried and packaged.

Are steviol glycosides natural?

Steviol gly­co­sides are nat­u­ral­ly found in ste­via plants, and they are extract­ed in a way that is sim­i­lar to how sug­ar is extract­ed from sug­ar beets and canes. Nevertheless, ste­vi­ol gly­co­sides must not be called nat­u­ral­ly accord­ing to EU leg­is­la­tion. However, it is ok to say that ste­vi­ol gly­co­sides are of nat­ur­al origin.

Are steviol glycosides ecological?

Steviol gly­co­sides extract­ed from organ­i­cal­ly grown ste­via must not be called organ­ic accord­ing to EU leg­is­la­tion. This is because an ion exchange resin is used in the extrac­tion process.

Is it challenging to replace sugar with steviol glycosides?

There are of course chal­lenges in replac­ing bulk sweet­en­ers such as sug­ar with ste­vi­ol gly­co­sides. Only 3 grams of Reb A or Reb M are need­ed to replace 1 kilo­gram of sug­ar. What should the oth­er 997 grams be replaced with to main­tain the same tex­ture and mouth­feel? And how should the off-taste and after­taste of the cheap­er Reb A be handled?

The solu­tion is sweet­ened fibres. It is sug­ar-like par­ti­cles con­sist­ing of dietary fibre wrapped in ste­vi­ol gly­co­sides and oth­er ingre­di­ents nec­es­sary to obtain its desired prop­er­ties. Sweetened fibres replace sug­ar one-by-one with unchanged taste and tex­ture. One kilo­gram of sug­ar is replaced by one kilo­gram of sweet­ened fibres. It can also be trans­port­ed, stored and used as reg­u­lar sug­ar with­out any changes in rou­tines or processes.

We have devel­oped sweet­ened fibres for many typ­i­cal appli­ca­tions (for exam­ple, bak­ery, choco­late, con­fec­tionery, dairy, soups and sauces). We mar­ket them under the trade­mark EUREBA®. They are ready to use as sug­ar replace­ment with lit­tle or no fine-tun­ing. That saves valu­able time and short­ens the time to mar­ket for sug­ar-reduced products.

We can also help you to cus­tomize your own sweet­ened fibres. We then use our own assort­ment of Reb A and Reb M, which we mar­ket under the trade­mark NAVIA®.

Read more

Read more about ste­via and ste­vi­ol gly­co­sides in our online mag­a­zine. Start with these articles: