September, the time before the plant starts flowering, is the ideal harvesting period. The leaves can be conserved by freezing or drying them, or they can be processed directly fresh.
Stevia as a sugar alternative
Compared to regular household sugar, the leaves of Stevia are about 40 times sweeter. The pure Stevioside of the plant has even 300 times the sweetening power. In addition to its classic use for tea and mate, the sweetener is often used in baking or cooking, because Stevia is extremely heat-stable. It is the two main components Rebaudioside A and Stevioside that give the leaves their special sweetness. The molecule contained in these two substances is so stable that it leaves the human body without any changes through the digestive tract. For this reason, no release of the hormone insulin is produced, nor is the blood sugar level affected in any way. This makes the sweetener especially interesting for diabetics. Because Stevia has a light, liquorice-like aftertaste, not everyone likes to use this sugar substitute.
Although the natural sweetener was not approved as a food additive in the European Union until 2011, Stevia is not a novel product. It is believed that the native inhabitants of South America have been using the plant for centuries for drinks and medicine. In the meantime, the sweetener is also becoming increasingly popular in Asia. In Japan, for example, Stevia has been used since the 1970s for toothpaste, cakes, sweets and of course for sweetening hot drinks and desserts.
Besides the USA, the use of steviol glycosides has been the norm for years in Australia, the EU, Israel, New Zealand, Switzerland and many other countries.
The ingredients of Stevia leaves are completely calorie-free and tooth-friendly. In addition, the sweetener does not affect insulin and blood sugar levels. Despite these properties, the steviol glycosides contained in the leaves have about 300 times the sweetening power of conventional sugar. For this reason, the consumption of pure steviol glycosides, especially in higher doses, is neither edible nor recommended. In the meantime, however, there are mixed products that consist of both stevia extract and real sugar.
Since 2nd December 2011, steviol glycosides have been approved as food additives in the EU and are available on the market. However, Udo Kienle warns against some details that should be taken into account when buying – especially on the internet. “Stevia products in any form, which are available in supermarkets, drugstores or organic shops, can be bought without hesitation, because these products are subject to strict regulations, like all foods in Germany”.
Always pay attention to the ingredients. Many Stevia products are offered with flavours, chemical sweeteners or fructose and dextrose. These additives are usually intended to conceal or mask the taste of inferior Stevia raw materials.
However, one should be careful when buying products on the internet: “Whoever buys this always takes a risk, because they don’t know what they are getting and whether the products have been sufficiently tested.” Most important is the so-called purity content of the Steviolglycosides. If this value is lower than 95%, it is a product that is not authorised in the European Union. The same applies to products that are on sale. Especially dangerous are stevia powders, stevia tabs or stevia liquid sweeteners that do not have any content information at all. In this case, it is strongly advised not to buy them.
The Stevia plant is even said to have a medicinal effect – the ingredients are believed to be anti-inflammatory, anti-hypertensive, antibacterial, antioxidant and even anti-cancer. Stevia is also said to have a healing effect on kidney and intestinal diseases.