Friday, February 3, 2023

Stevia is a leafy alternative to sugar

Estimated reading time: 6 minutes

The overuse of refined sugar in processed foods such as cold drinks and pastries has been given the blame for various illnesses – from obesity to cancer. But what should a person with a sweet tooth do? If that craving hits, it hits you hard…

An ancient South American remedy might just be the answer for those who crave a long life filled with sweetness. Stevia is aptly named the “candy leaf” as it is much sweeter than sugar.

This means you get all the sweetness of sugar with none of the calories. No wonder sugar barons across the globe are either fearing or embracing this sugar substitute. Besides being a natural alternative to sugar (derived from sugarcane or sugar beet), stevia can also be used in either liquid or powdered form, which means the confectionary options are literally endless.

Rabobank, the Netherlands- based agro-financing giant, is positive about the future of stevia. In its report, “Stevia and the US market”, Rabobank stated that stevia sales should reach the $700 million mark by the end of this year (2015). Not bad for a herb that has only recently (2008) been labelled as safe for human consumption by the American Food and Drug Agency (FDA).

China and Brazil are responsible for 90% of the global production. Harvests vary between 1 500kg and 3 000kg per hectare. For Stevia extract alone the market is estimated at 1,5 billion kilograms, converted from 12 million kilograms of leaves.

Read more about the effect of the KZN floods has on sugar production here.

What is stevia?

Relatively new herb for Western foodies, but the Guarani tribe of South America has used it for around 1 500 years. This herb is part of the chrysanthemum family and naturally grows as a small shrub in Paraguay and Brazil. The herb’s leaves are extremely sweet due to the 10% stevioside that can be found in them.

To the untrained eye stevia might almost look like a type of mint, but the herb’s principle characteristic is its extreme sweetening power. Besides this it also has therapeutic properties, particularly for fighting obesity, diabetes and hypertension, according to GHE, a leading European hydroponics company.

Stevia principally contains steviosides and rebaudiosides. The intensity of its sweetness and taste is proportionally dependent on its content of four major diterpenic glycosides found in the leaves, veins and stems: Stevioside (5 to 10%), rebaudioside A (2 to 4%), rebaudioside C (1 to 2%) and dulcoside A (0,5 to 1%). These glycosides are between 40 and 250 times sweeter than the sugar we commonly consume.

Steviosides are rather bitter, while rebaudiosides are sweet (www.puresweet.com.au).Stevia is a small, dense shrub of roughly 50 to 80cm in height when growing wild, reaching up to 1m in height when cultivated. It has intense green lanceolate leaves growing diametrically opposite on the stem. Its flowers are small and white, and its tiny seeds are plentiful yet difficult to germinate. The roots are fibrous and dense.

The leaves are the part being utilised, bearing in mind that from the time the plant starts budding its active principle concentration decreases. It is a hardy sub-tropical plant which is affected by frost. Its ideal temperature is between 15°C and 26°C. It prefers light and should be placed in full sunlight when outdoors.

How is it grown?

The green light for stevia consumption in South Africa was given in September 2012. Therefore it is understandable that there is no local commercial crop to be found as there is no local processing plant that can convert stevia leaves into consumable syrup or powder. Due to this all stevia, which are used on a commercial scale, are currently imported.

The first commercial US stevia crop was planted in 2010 in California, according to the newspaper Western Farm Press. This planting was due to a collaboration between S&W Seed Co. and PureCircle Limited, a leading United States producer and marketer of stevia. Mark Grewal, chief executive officer and president of S&W Seed Co, said at the time of planting that stevia will be bigger than almonds and it will eventually replace sugar cane and sugar beets.

GHE states that stevia can also be grown hydroponically. The herb needs little fertilisers, so it can be grown on relatively poor land, bearing in mind that it does need significant amounts of phosphate. Furthermore the plant must be watered regularly and it prefers wet soil, rather than dry soil.

If the roots are cared for, the plant can be harvested up to five times a year for about six years. It might seem easy to grow, but there are a couple of technical barriers to overcome. For a start you have to germinate the seeds. GHE’s scientists have sown the seeds in large quantities, only to have limited results. Nowadays they rather take cuttings, which are much more successful.

Stevia’s known enemies are primarily aphids and slugs, and it could also contract a fungal disease (septoriosis). Harvest must take place between August and September, before budding commences.

Read more about the upcoming sugar tax here.

Processing the leaves

Stevia could be processed to be either a liquid or a powder. Liquid stevia extract has either a water, glycerine, alcohol or grapefruit base. The glycosides are extracted from the leaves using either water or alcohol and membrane filtration.

Because it evaporates, no alcohol remains in the finished product. The liquid becomes clear rather than green because the extraction process removes the chlorophyll, and white glycosides remain. No bleach or other chemical whiteners should be used, according to the American-based SweetLeaf Company.

Dark stevia concentrate is a thick, dark-brown liquid that makes a good substitute for brown sugar and molasses. It is made by boiling the stevia leaves in water, cooking them without any chemicals or alcohol, until the proper thickness or concentration is reached. The result is similar to a “reduction”, which is a sauce that has been thickened by boiling off the liquid.

Powdered stevia is a white, powdered extract, produced in bulk or in packets, and blended with a filler, usually fructo-oligosaccharides (FOS), which is a plant-based fibre. This is the most processed form of stevia. “Production” of stevioside involves water extraction from the dried leaves, followed by clarification and crystallisation processes. Commercial processes usually consist of water extraction, decolouration and purification using ion-exchange resins, electrolytic techniques or precipitating agents.

These are highly technical processes and are one of the biggest reasons why stevia production hasn’t started in South Africa.

Stevia products

Stevia-based products can shops, convenience stores or even online. Stevia can be found in the Equisweet range of Huletts, traditionally known as a sugar producer. It is sold in tablet and powder format.

Delite Foods (www.delite.co.za) is another food company that offers consumers stevia-based products. These products can be found in the sweetener aisle or consumers can buy the products online. As far as taste is concerned, stevia manufacturers still have a few kinks to sort out as the plant has a definite bitter aftertaste. However, should this issue be overcome there is probably no reason why stevia cannot become a daily staple in numerous households. – Susan Botes-Marais, Plaas Media

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