Stevia (Stevia rebaudiana) is a sweet-tasting
plant which became well-known only in recent years worldwide. However, the
sweet taste of its leaves has been known
for hundreds of years to indigenous populations of Paraguay and Brazil, which
they used it as a sweetener in tea or in local traditional medicine recipes.
Today, stevia is used commercially around the world to replace sugar in soft drinks and foods, providing an important aid in calories consumption reduction and it is available in market both in powder and liquid forms. Stevia is a very good substitute for sugar because it has little caloric value and is grown essentially for its leaves, because its leaves are rich in glycosides. The steviol glycosides contained in stevia leaves have a strong sweetening power as they are 350 times sweeter than table sugar, which means that a small quantity of stevia is needed to present the sweet taste we want.
Stevia can be grown either by professional farmers or
amateurs and can be planted in pots or gardens to meet the daily needs of a
household. The usual loamy soil that common plants and vegetables need is also
ideal for stevia plantation, which usually prefers neutral pH (pH 7) and not
very heavy soils. Its seeds should remain in the nursery for at least 8-10
weeks before being transported outside and its seedlings will appear in 7-14
days. Once the nursery period is over the plants should be transplanted into
pots or the garden, making sure that the temperatures during the night do not
fall below 10 °C. The best period of harvesting stevia is the period just
before flowering, which is good to coincide with a period of 80-85 days after
transplantation, and usually the best season is autumn when the day begins to
get shorter.
Stevia leaves are used in dried form and in order
to dry them we have to leave them under the sun for up to 12 hours but no
longer, because the glycosides content of the final product will
be reduced. In addition, desiccation of stevia leaves should be done
immediately after harvesting, otherwise the leaves lose their good quality
because the glycosides they contain are reduced in this case too. Stevia dried leaves can be
kept for years in glass jars and we can use them as they are or by grinding
them in the mortar whenever we want a quantity of sweetener for our household's nutritional
needs.