The stevia plant has an enormous sweetening power. What is the reason for the sweetness of stevia leaf extracts ? How does the sweetness come from nature into the kitchen? Learn more about steviol glycosides, the sweet compounds of the stevia plant.
What are steviol glycosides?
The sweetness of stevia comes from its leaves which produce the steviol glycosides – the natural sweeteners of the plant. The leaf extract of the stevia plant contains at least ten steviol glycosides in different concentrations:
- Dulcoside A
- Rebaudioside A
- Rebaudioside B
- Rebaudioside C
- Rebaudioside D
- Rebaudioside E
- Rebaudioside F
These steviol glycosides differ in their molecular structure, their sweetening power and their taste. The sweet taste of the plant is mainly produced by stevioside and Rebaudioside A. As stevioside is the largest part of the steviol glycosides in the plant, stevia leaf extracts are sometimes mistakenly called stevioside.
Extraction of steviol glycosides
In order for stevia leaf extracts to be used in food, these extracts must strictly adhere to established specifications of identification and purity established by national and global food safety authorities. These specifications clearly outline the process and which food grade alcohols have been included in safety evaluations and are accepted for use in the extraction of steviol glycosides.
Stevia extracts are removed from the leaves of the stevia plant by traditional water/alcohol extraction methods which do not alter the composition of the plant’s sweet compounds. The process involves steeping the dried leaves of the stevia plant in water, filtering and separating the liquid from the leaves and stems, and further purifying the remaining plant extract with either water or food grade alcohol. Stevia extracts are exactly the same compound outside the leaf as they are found in the leaf. The goal of this process is to extract and purify the natural substances (steviol glycosides) from the leaves of the plant. The result is a white natural substance which contains at least 95 % steviol glycoside and is 200 to 300 times sweeter than table sugar.