There are several Stevia plant strains. I grow and use the Bertoni strain as it is far sweeter.
If I put more than about 1/8 tsp. in my coffee, it is too sweet to drink.
I’m growing some too to dry and process to powder, but this article talks about fermenting it. How do you ferment it?
I found this from AI
How Do You Ferment Stevia?
Fermenting stevia is a fascinating area, especially with recent research highlighting its potential benefits beyond just sweetness. Here’s a breakdown of how it’s done, both on a research/industrial level and what you might encounter in terms of home applications:
Why Ferment Stevia?
* Enhanced Bioactivity: Recent studies, particularly from Hiroshima University, show that fermenting stevia with specific bacteria (like Lactobacillus plantarum SN13T from banana leaves) can significantly enhance its beneficial properties. This fermentation process can create new bioactive compounds (like chlorogenic acid methyl ester - CAME) that have shown promising anti-cancer and antioxidant effects, even surpassing non-fermented stevia extract.
* Improved Flavor Profile: Traditional stevia extracts can sometimes have a bitter aftertaste. Fermentation, especially lactic acid fermentation, can help eliminate or reduce these off-flavors, resulting in a purer and more pleasant sweet taste.
* Production of Specific Steviol Glycosides: Some industrial processes use fermentation with genetically modified microorganisms to produce specific steviol glycosides, like Rebaudioside M (Reb M) and Rebaudioside D (Reb D), which are highly sought after for their superior taste profile and are found in smaller quantities in the stevia plant itself.
How Stevia is Fermented (General Principles and Research Methods):
* Raw Material Preparation: This typically involves taking fresh or dried stevia leaves. For some methods, the leaves are processed similar to green tea (e.g., curing, drying), and then crushed into a powder.
* Lixiviation (Extraction): The stevia material is leached with hot water to extract the steviol glycosides. The ratio of stevia powder to water and the temperature and duration of this leaching process can vary. The resulting filtrate is collected.
* Sterilization: The stevia extract is often sterilized (e.g., at high temperatures for a short period) to eliminate unwanted microorganisms and create a clean environment for the inoculated bacteria.
* Inoculation with Starter Culture: This is the crucial step for fermentation.
* Lactic Acid Bacteria: For enhanced bioactivity and flavor improvement, specific strains of lactic acid bacteria (e.g., Lactobacillus plantarum SN13T) are inoculated into the stevia extract.
* Genetically Modified Microorganisms: In industrial settings, genetically modified yeast or other microorganisms are used. These microbes are engineered to consume simple sugars and produce desired steviol glycosides like Reb M.
* Fermentation: The inoculated mixture is incubated under controlled conditions (temperature, oxygen levels, duration). For example, research on anti-cancer properties found optimal fermentation at 37°C for 72 hours, in an oxygen-free environment.
* Concentration and Purification (Industrial): After fermentation, the product may be concentrated (e.g., to create a concentrated juice) and further purified to isolate the desired compounds. The microorganisms or enzymes used in the process are removed from the final product.
Fermenting Stevia at Home:
While the complex industrial and research-level fermentation of stevia for specific glycosides or anti-cancer compounds isn’t feasible for a home setting, you can engage in simpler forms of “fermented” stevia or use it in fermented products.
* Water-Fermented Stevia Extract (Herbal Infusion): Some home methods involve steeping dried stevia leaves in water for an extended period, sometimes with a cloth cover to allow for some natural fermentation (though this is more of an infusion with potential wild fermentation rather than controlled microbial conversion of steviol glycosides).
* Process: Heat water to just under boiling, add dried stevia herb to a jar, pour hot water over it, stir, cover with a cloth, and leave at room temperature for a few hours, then refrigerate for a day or two before straining.
* Note: This might yield a less bitter extract than some commercial products, but it’s not truly transforming the steviol glycosides in the same way as specialized bacterial fermentation.
* Stevia in Fermented Beverages: Stevia itself, especially pure steviol glycosides, is generally not fermentable by common yeast and bacteria because it lacks calories (sugars) for them to consume.
* If you’re making a fermented beverage (like kombucha, water kefir, or ginger ale) and want to sweeten it without adding fermentable sugars, you can often add stevia after the primary fermentation is complete. This allows the microbes to consume the original sugar, and then you can adjust the sweetness to your liking with stevia without restarting fermentation.
* Some experiments show that if you try to ferment with stevia as the sole sweetener, it may fail, and mold could even form because the microorganisms don’t have a food source.
Important Considerations:
* Purity: For home use, sourcing good quality, pure stevia (dried leaves or high-purity extract) is important.
* Safety: When attempting any home fermentation, ensure proper sanitation to prevent the growth of undesirable microorganisms.
* Expectations: Home fermentation of stevia will not yield the same specific bioactive compounds or highly purified steviol glycosides as specialized industrial or research processes. The primary benefit for home users might be a slightly improved taste profile or using stevia as a non-fermentable sweetener in other fermented products.
If you’re interested in the advanced, beneficial fermentation of stevia, that is primarily happening in scientific research and industrial production. For home use, focus on making extracts or using it in conjunction with other fermented foods.