Stevia – from seed to Eureba

Stevia is a herb that grows wild in the rain forests of Paraguay. It's cultivated in various places over the world for its sweet taste. The steviol glycosides extracted from its leaves are the most commonly used sweetener from a natural source. However, the intense sweetness is a challenge for the food and beverage industry. Eureba is the solution for this. It replaces sugar one-to-one, with fewer calories.

23 May 2019 •

Stevia thrives in humid sub­trop­i­cal climates.

Stevia (Stevia rebau­di­ana bertoni) is a herb indige­nous to the rain­for­est in Paraguay. The leaves, which in their dried form are thir­ty times sweet­er than sug­ar, have been used as a sweet­en­ing agent by the guaraní Indians for over 1,500 years.

In the end of the 19th cen­tu­ry the Paraguayan chemist Ovidio Rebaudi start­ed to study ste­via. He dis­cov­ered the sub­stances respon­si­ble for the leaves’ sweet flavour — ste­vi­ol gly­co­sides. They are up to 300 times sweet­er than sugar.

This is the sto­ry of how the sweet herb is grown and har­vest­ed. How the sweet sub­stances in the plant are extract­ed and puri­fied. And final­ly, how we at Bayn process them to Eureba which enables you to use the sweet­ness of ste­via with­out hav­ing to alter your recipes.

Some facts about stevia

Stevia is a del­i­cate herb which requires warm and humid air. It does­n’t tol­er­ate cold tem­per­a­tures but loves the sun. As a con­se­quence it is grown pre­dom­i­nate­ly in humid, sub­trop­i­cal climates.

Stevia is one of a hun­dred or so species of the same fam­i­ly, which also holds plants such as daisies, hawks­beards and this­tles. It grows to about 30–80 cm high, has leaves that are about 2.5 cm long and it has white flowers.

Commercial cultivation of stevia

Stevia seeds are hard to cul­ti­vate — only one in ten ger­mi­nates. This puts high demands on a con­stant­ly warm and humid soil. Furthermore, the sweet­ness varies from plant to plant.

This is why ste­via is usu­al­ly cul­ti­vat­ed from cut­tings. They are allowed to grow for 10–12 weeks before they are trans­ferred to the field, where they will get the sun they need to achieve the right sweetness.

After 3–5 months the plant is ready to be har­vest­ed. If done care­ful­ly you can har­vest leaves from the same plant, sev­er­al times a year, for a peri­od of 2–3 years. But then the top flow­ers must always be removed; if ste­via is allowed to flower it loos­es a lot of its sweet­ness. You can also har­vest the entire plant in one go, in this case it is cut at about 5–10 cm above the soil.

The first suc­cess­ful attempt at cul­ti­vat­ing ste­via took place in Paraguay in 1908. The coun­try now has com­pe­ti­tion from the USA, Kenya and China. The largest farms are in China, close to the Chinese city of Jining in the Shandong province.

Stevia as a raw material

The har­vest­ed parts of the ste­via plant are dried imme­di­ate­ly to avoid any oxi­da­tion which would reduce the sweet­ness significantly.

The quick­est way is to let the leaves dry in the sun. After 9–10 hours the humid­i­ty has decreased by 90 per cent. The dry­ing can also be done in a furnace/​oven, but this takes a longer time, and high tem­per­a­tures risk affect­ing the sweet­ness too.

When the har­vest­ed plant has been dried, the leaves are sep­a­rat­ed from the stems, as the stems have no sweet sub­stances. This can be done man­u­al­ly or by machines.

The dried leaves are now ready to be sold globally.

Stevia in foods

Dried ste­via leafs.

The dried ste­via leaves can be used just as they are. But not just in any giv­en man­ner; ste­via is a new food sub­stance in the EU and the European author­i­ty for food safe­ty (EFSA), must car­ry out food safe­ty checks for each use, except for teas, herbal teas and fruit infusions.

It is how­ev­er allowed to use the sub­stances that gives ste­via its sweet­ness: ste­vi­ol gly­co­sides. The National Food Agency in Sweden has the fol­low­ing statement:

Are steviol glycosides an approved additive?

Yes, ste­vi­ol gly­co­sides (E960), extract­ed from the plant ste­via are allowed as an addi­tive. The addi­tive has been sub­ject­ed to exten­sive safe­ty checks and is allowed to be used as a sweet­en­ing agent in lim­it­ed amounts. In the EU list of food addi­tives you can read about in which foods and bev­er­ages you can use ste­vi­ol gly­co­sides and in what amounts.

Steviol gly­co­sides is the most com­mon­ly used sweet­en­ing agent from a nat­ur­al source. But how are they extract­ed from the dried ste­via leaves?

From stevia to steviol glycosides

The ste­vi­ol gly­co­sides extrac­tion process is sim­i­lar to that of how sug­ar extract­ed from sug­ar beets.

First, the leaves are soaked in hot water. Just like when you let tea steep in a cup of hot water, but on a much larg­er scale.

After a few min­utes the ste­via leaves are removed and the “tea” is puri­fied in sev­er­al steps from plant pig­ment, gelati­nous sub­stance, oil, wax, pro­teins, as well as tan­nic acid and oth­er polyphenols.

The puri­fied “tea” is then fil­tered through a porous mate­r­i­al that catch­es the ste­vi­ol gly­co­sides but lets through the water. Similar to a filter.

Now, the snag is that the ste­vi­ol gly­co­sides are stuck to the “fil­ter”. To release them the fil­ter is rinsed with pure alcohol.

The next step is to get rid of the alco­hol. A lot can be sep­a­rat­ed with a mem­brane fil­ter, but the very last must be removed through dis­til­la­tion. And it’s not the alco­hol we want to savour here, but what is left — a sweet syrup.

The ste­vi­ol gly­co­side solu­tion is then sprayed under high pres­sure into a tank filled with hot air. When the mist meets the hot air the very last of the flu­id evap­o­rates and crys­tals of ste­vi­ol gly­co­sides fall like snow — ready to be used.

YouTube video

Challenges with steviol glycosides

Steviol gly­co­sides.

Steviol gly­co­sides are about 300 times as sweet as sug­ar. It is one of the main advan­tages with this sub­stance. (Other advan­tages are that it comes from nat­ur­al sources and adds zero calo­ries to formulations.)

But the intense sweet­ness of the ste­vi­ol gly­co­sides also presents its biggest issue. You can­not replace 1 kilo of sug­ar with 3 grams of ste­vi­ol gly­co­sides. Both vol­ume and struc­ture in the prod­uct will be affect­ed if you do this.

Besides, ste­vi­ol gly­co­sides have a slight­ly bit­ter taste and a metal­lic after­taste, not exact­ly a desir­able outcome.

This puts high demands on food and bev­er­age man­u­fac­tur­ers who want to use ste­vi­ol gly­co­sides to reduce sug­ar in their prod­ucts. They must be pre­pared for long R&D process­es and large invest­ments to devel­op recipes that taste as if they were made with sugar.

This pos­es no prob­lem to the giants in the indus­try. They have their own R&D depart­ments, and both time and a large enough bud­get. Medium sized com­pa­nies are worse off.

What if…

If you work in a medi­um sized food and bev­er­age com­pa­ny you know full well that there is not enough time and mon­ey (and per­haps not knowl­edge either) to devel­op new recipes with ste­vi­ol gly­co­sides instead of sugar.

Now, if there only was a ste­via based ingre­di­ent that replaces sug­ar one-to-one (1 kilo of sug­ar is replaced with one kilo of ste­via ingre­di­ent) with the same mouth­feel (the same tex­ture and taste).

There is such an ingre­di­ent. We call it Eureba.

Eureba

The dietary fiber we use in mak­ing Eureba comes from dif­fer­ent plants. For exam­ple, chico­ry root (pic­ture) and cas­sa­va root.

The nifty thing about Eureba is that it is a solu­tion, where the ste­vi­ol gly­co­sides are attached to plant fibres. In this way you can replace one kilo of sug­ar with one kilo of Eureba.

We use dif­fer­ent plant fibres for dif­fer­ent appli­ca­tions. In jel­ly sweets, for instance, we use fibres from the cas­sa­va root. In oth­er appli­ca­tions we use fibres from oth­er nat­ur­al sources, like the chico­ry root.

The plant fibres solve the prob­lem with vol­ume and tex­ture. But to get the right mouth­feel we some­times need to add sug­ar alco­hols (e.g. ery­thri­tol), which also has its ori­gin in nature.

You don’t need to wor­ry about which fibres and sug­ar alco­hols might be applic­a­ble to your recipe. We have already done that for you. There are ready-made Eureba solu­tions for a num­ber of appli­ca­tions, like ice cream, choco­late and bak­ery products.

And to conclude

If you have read this far, you might be inter­est­ed in find­ing out more about Eureba. Perhaps we have a solu­tion for your par­tic­u­lar needs. (There’s a big chance of this. If not, we can devel­op one for you.) Don’t hes­i­tate to con­tact us. We’d be hap­py to answer your ques­tions. Call us on +46–8‑613 2888 or send us an e‑mail at info@​bayn.​se.

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