Water Kefir: A Sparkling Ferment
How to master water kefir fermentation for a unique, sustainable, and probiotic-rich soda
Water kefir, also known as tibicos, is a lightly effervescent, probiotic-rich beverage made using water kefir grains, a SCOBY that thrives in a sugar-water environment. This refreshing, slightly tangy drink is an excellent option for those seeking a non-dairy, vegan-friendly probiotic alternative and a versatile source of acidity for cocktails.
What Are Water Kefir Grains?
Water kefir grains are translucent, gelatinous clusters of bacteria and yeast. The microbial composition of water kefir grains is predominantly composed of lactic acid bacteria (LAB), making lactic acid fermentation the most significant metabolic process during fermentation. The grains contain approximately 70% Lactobacilli, 10% Leuconostocs, 10% Acetobacteria, 5% Bifidobacteria, and 5% other bacterial genera. Notably, species such as Lactobacillus hilgardii and Lactobacillus nagelii produce exopolysaccharides that contribute to the grains' structure. Yeasts, including Saccharomyces cerevisiae (which is always present), Candida, Hanseniaspora, and Guehomyces, play a vital role in fermenting sugars and interacting with bacteria.
Unlike milk kefir grains, which rely on lactose, water kefir grains thrive on sucrose and other simple sugars. The grains cannot be artificially created and grow slowly with each batch.
Fermentation Process
Water kefir fermentation involves three primary types of fermentation: lactic acid, alcoholic, and acetic acid fermentation.
Lactic Acid Fermentation: The lactic acid bacteria (LAB), particularly Lactobacillus species, break down sugars—primarily sucrose—into lactic acid. This process lowers the pH to a range of 3.5-4.5, creating the tangy flavor characteristic of water kefir. Sucrose is the most favorable sugar for water kefir fermentation, as it is effectively metabolized by both bacteria and yeast.
Alcoholic Fermentation: Yeasts such as Saccharomyces cerevisiae ferment the sugars into ethanol and carbon dioxide, producing mild carbonation and a trace amount of alcohol (typically less than 1%).
Acetic Acid Fermentation: Acetobacter species convert the ethanol produced by the yeasts into acetic acid, contributing slight acidity to the final product.
Temperature, Time, and Brix Levels
Water kefir fermentation is best carried out at room temperature, typically between 20°C and 30°C (68°F to 86°F). At these temperatures, fermentation lasts 24 to 48 hours, with shorter fermentations yielding a milder, sweeter beverage and longer fermentations producing a more tart, effervescent result.
The optimal sugar concentration for fermentation, measured in Brix (°Bx), ranges between 8-12°Bx. When the sugar content falls below 5°Bx, the bacteria can become sluggish, while concentrations above 12°Bx can inhibit the activity of some LAB and yeasts. Maintaining this range ensures balanced microbial activity and a well-fermented water kefir.
LAB thrive best in environments where the Brix level initially starts around 8-10°Bx, as it provides an ideal balance of sugar availability for metabolic activity and prevents osmotic stress that could hinder bacterial growth.
Water Kefir Recipe
Ingredients:
20 grams of water kefir grains
1 liter of filtered water
80 grams of sugar (organic cane sugar or unrefined sugar, 8% Brix)
Optional: a slice of lemon
Instructions:
Dissolve the sugar in 1 liter of water, ensuring it is fully dissolved.
Add the water kefir grains and optional fruit or lemon slice to the jar.
Cover loosely with a cloth or breathable lid to allow airflow.
Ferment at room temperature (20-28°C) for 24-48 hours.
Starting Brix: 8-10°
Starting pH: 5.8-6.5
After 24-48 hours, check for taste, and measure the Brix and pH.
Final Brix: 3-5°
Final pH: 3.5-4.5
Strain the grains, reserving the liquid. The grains can be reused for the next batch.
Optional second fermentation: Bottle the strained liquid with fruit for 12-24 hours to add more flavor and carbonation.
Water kefir is a dynamic, probiotic-rich beverage where lactic acid fermentation dominates, thriving in a carefully balanced environment of simple sugars and optimal conditions for both bacteria and yeast to create a refreshing and effervescent drink. Whether you're looking to serve a unique ferment at your bar or restaurant or simply want to brew it at home, water kefir offers an exciting opportunity for flavor transformation, sustainable beverage practices, and a distinctive feature on any menu.
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Denis Pashkov
cosmos society