The art & science of fermenting kombucha tea

Over the past ten years kombucha has grown tremendously in popularity in the Pacific Northwest. A decade ago, many people would sneer at the mention of a  “fermented tea”, and yet today, you’d be hard-pressed not to find various flavours of kombucha stocked at the local grocers.

Kombucha is a fermented tea that originated in Asia. The tea is fermented with a symbiotic culture of bacteria and yeast (SCOBY), which somewhat resembles a mushroom cap. While kombucha is a fermented food, compared to lactic acid fermentation (i.e. saukerkraut, kimchi), the microbial composition varies more batch to batch, dependent on the individual SCOBY. Therefore, it is difficult to say without testing, which specific bacteria or yeast are present in the fermented tea, and whether it could be considered a source of probiotics.

Kombucha has taken on the role of a “super food”, and the list of purported health benefits seems to grow every year. It has been claimed to “reduce blood pressure and lower cholesterol”, “reduce the spread of cancer”, and “improve immunity”. The reality is, none of these claims are supported by science or human clinical trials.

Kombucha, as we know it today, is a fermented, flavourful, carbonated beverage. It often contains less sugar than other beverages, such as juice and soda. It offers an opportunity to use local fruit and herbs to create a refreshing drink. It contains the nutritional properties of the tea, fruit and herbs used to make it.

We thought it was pertinent to clarify that kombucha is not the wonder drink it’s often declared to be. However, there’s also no harm in enjoying a glass of this delicious, bubbly beverage every so often.

We love to make kombucha, testing out different flavours and utilizing different herbs. Like all fermented foods, you need to follow proper technique to avoid contamination of your kombucha batch. This kombucha recipe closely follows the methods for brewing a classic kombucha from sweetened black tea.

Getting Set-up

You will need a SCOBY to start making kombucha. You can obtain a SCOBY from someone who is successfully brewing kombucha, or from various retailers, such as Cultures for Health.

Brewing kombucha does not require a lot of equipment. You will need a large wide-mouthed glass jar (at least 4 litre capacity). Avoid using a metal or ceramic container; the acid in the kombucha can react poorly with the metal. You will need a piece of cheese-cloth or cotton cloth to cover the opening of the jar and a large elastic band, to fasten the cloth down.

—Sarah 

Makes approximately 3 litres.

1. 
Boil 2 cups of water in a pot and add 1 cup of sugar, stirring continuously until it has dissolved. Remove the pot from the heat and add the tea. Allow the tea bags to steep for 10 minutes. 
2. Once the tea has steeped, remove the tea bags, and add the mixture to the clean, large wide-mouthed jar. Add in the remaining 11 cups of water, and stir to mix.To kick-start the fermentation process, add in 2 cups of unpasteurized kombucha from a previous batch (also known as starter tea).  Generally 10–20% of the total volume of kombucha should be starter tea – to initiate timely fermentation.
3. Put on your gloves, and transfer the SCOBY to the jar. 
4. Cover the top of the jar with the cloth and fasten with a large elastic band. Label the kombucha with the start date of fermentation. 

First Fermentation

1. The first fermentation takes approximately 7- 10 days, depending on the temperature of the room it is in. You will notice signs of fermentation such as the formation of small bubbles. Your SCOBY will grow and will rise to the top of the jar. Over time the bacteria and yeast will metabolize the sugar to acetic acid and carbon dioxide. Typically the acetic acid and alcohol concentration of kombucha is less than 1%.
2. The pH of the kombucha will drop from around 5 to 2.5 during fermentation. If the pH of the kombucha does not drop below 4.2 after 7 days of fermentation, then the batch could be contaminated with bad microorganisms. You can measure the pH using a calibrated pH meter.
3. If you notice that there is colourful mould (green, pink or black) on your SCOBY, throw the batch out! It often means that there was not enough started tea in the batch.
4. Around the 7-day mark, start testing your kombucha, for the desired taste. Once it almost has the flavour profile you desire (the balance between sweetness and acidity), the first fermentation is done. If you prefer more of a sour kombucha, let it ferment a couple days longer.

Second Fermentation

1. Remove the SCOBY from the jar, and along with 2 cups of  kombucha, place it in a clean, glass container for the next fermentation.
2. Divide the remaining kombucha into your sterilized swing-top jars or bottles.  These jars and bottles are designed to withstand the pressure of the fermenting kombucha. We use wide-mouthed swing-top jars because of the convenience of cleaning them.
3. For the second fermentation, you can use fruit juice, fresh fruit or herbs. We often opt for the whole fruit and herbs, because of the lower sugar content and the complex flavours. Check out our recipe on Kombucha flavours for some inspiration. The amount of added fruit or herbs should not be more than 10- 20% of the total batch volume.
4. Wash and cut the fruit up into small bite-sized pieces. Add the fruit to the wide-mouthed swing-top container, and close.
5. Allow the kombucha to ferment for 1–2 days, continually testing it for the desired taste.

Third Fermentation (optional)

1. Once the kombucha has the appropriate flavour, then you can do a third fermentation. Strain the fruit/herbs using a fine-mesh sieve into a sterilized container. Pour the kombucha back into the swing-top container. Seal, and allow the kombucha to sit for another 1-2 days, until the desired carbonation is acquired.
2. You will have to “burp” the container, releasing the gas to prevent the pressure from building up too much.
3. Store in the fridge, and consume within 2 weeks. Enjoy.

Please note: pregnant women, or individuals with significant liver or kidney disease should not consume kombucha.

Further ideas and modifications

• You can opt to use honey and green tea to make a Jun tea.
• There are endless opportunities for flavour combinations – so be creative and have fun!

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