Creating Your Own Kombucha Recipe
Kombucha fermentation explained – detailed recipe and tips for brewing your own kombucha
Kombucha is a fermented beverage made by combining sweetened tea with a symbiotic culture of bacteria and yeast (SCOBY). The SCOBY breaks down the sugars into ethanol and lactic acid during fermentation. Acetic Acid Bacteria (AAB) then convert these into acetic acid, giving kombucha its distinctive tangy flavor. Because the AAB immediately convert the ethanol and lactic acid as they're produced, the alcohol content remains low throughout the process. All of these fermentations occur at the same time, and the kombucha will keep fermenting until it’s completely dry. This process also generates carbon dioxide, which adds natural fizziness and enhances its acidity.
Simultaneous fermentation in kombucha involves a delicate balance of three types of fermentation: ethanol, lactic acid, and acetic acid.
Yeasts first convert sugars into ethanol and carbon dioxide. Simultaneously, Lactobacillus bacteria produce lactic acid. Acetic Acid Bacteria oxidize the ethanol and lactic acid into acetic acid, which gives kombucha its tangy taste. This intricate fermentation happens in parallel because the yeast and bacteria coexist in the SCOBY, each thriving in slightly different conditions. As yeast produces ethanol, AAB consume it, preventing significant alcohol buildup. The balance of these fermentations is what shapes kombucha's unique flavor, acidity, and slight effervescence, while promoting a complex mix of acids that contribute to its probiotic benefits.
While the SCOBY pellicle (the floating layer) is often visible, it's the liquid from the previous batch that is most important. This liquid, rich in active cultures, essentially acts as the true SCOBY, driving the fermentation process. The pellicle will form naturally, but it’s the starter liquid that ensures a successful kombucha batch. The SCOBY pellicle forms when Acetic Acid Bacteria oxidize ethanol at the surface, producing cellulose as a byproduct. This cellulose accumulates and binds together, creating the mat-like structure. Oxygen exposure at the surface is crucial for its development.
Basic Kombucha Recipe
Ingredients:
3.75 liters water
250 grams sugar
10 grams black tea
250 ml starter liquid
Kombucha mother (SCOBY) – optional
Method:
Dissolve 250 grams of sugar in 3.75 liters of boiling water. Add 10 grams of black tea, steep, then strain and cool. Once cooled, combine with 250 ml of starter liquid in a clean jar. Add the SCOBY pellicle, cover with a breathable cloth or coffee filter secured with rubber bands, and ferment at 24°C–26°C, monitoring the Brix and pH daily. The SCOBY may initially sink but will typically float to the surface within a few days.
Monitoring Brix and pH Levels
At the start of fermentation, the Brix (a measure of sugar content) should be around 6.5-8°Bx, providing the right balance of sweetness. The starting pH should be at or below 5.5, with the pH of the starter liquid helping to lower the overall pH. Monitoring these levels daily is crucial, as the pH will gradually decrease as fermentation progresses, with a final target pH of around 2.5-3.5.
Flavoring Your Kombucha
To flavor your kombucha during secondary fermentation, add fruit or fruit puree to the already fermented kombucha. Monitor the Brix and pH of the kombucha before adding fruit. After adding fruit, expect the Brix to rise due to the added sugars and the pH to potentially drop further. Adjust fruit quantity as needed to achieve the desired flavor while maintaining proper fermentation balance.
Yeast activity in kombucha slows down significantly when the pH drops below 3.0 and the Brix level falls below 1°Bx. At these levels, the environment becomes too acidic and low in sugar, inhibiting yeast fermentation. Bear this in mind when choosing the right moment for secondary fermentation.
Tips for Brewing Kombucha
SCOBY Needs Caffeine: You can experiment with tisanes (herbal infusions), but be sure to supplement your SCOBY with black or green tea after each batch. Caffeine is crucial for its health and fermentation efficiency.
Flavoring with Herbs: While herbs can enhance your kombucha’s flavor, some, like sage or rosemary, in high concentrations, can inhibit fermentation. Introduce them cautiously.
Don’t Oversweeten: Know the Brix level of your fruits. If the Brix level rises above 14°Bx, both bacteria and yeast may become sluggish, stalling fermentation. Keep the sugar content balanced for optimal results.
Happy brewing!
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Denis Pashkov
cosmos society