Does kombucha have gas?

Kombucha may or may not have gas, depending on how it has been made. The first fermentation, which is done in an open container, does not produce gas in the liquid. The gas appears during the second fermentation in the bottle, when the yeasts continue to work with the residual sugar and added juices. In Mūn Kombucha, the gas is completely natural: we do not add CO₂.

The first fermentation does not generate gas in the liquid

When traditional kombucha fermentation is carried out, using a sweetened tea infusion and the SCOBY, it is done in an open container. Even if we cover it with a cotton cloth to prevent insects or dust from entering, the gas produced by the yeasts (CO₂) is not trapped in the liquid. If you taste this kombucha right after the first fermentation, you will notice that it has no gas.

Kombucha has gas when left to re-ferment in the bottle

When kombucha is bottled, it is sometimes flavoured with fruit juices. If you store this freshly bottled kombucha in the fridge, no gas is produced: the yeasts become inactive with the cold. But if you leave it to rest at room temperature, inside the bottle the active yeasts continue to ferment the residual sugar from the first fermentation and the sugar provided by the juices. This CO₂ can no longer escape and accumulates in the liquid. This process is the second fermentation.

The three variables that generate gas

For a bottled kombucha to develop gas, three simultaneous conditions must be met:

• That it contains live yeasts.
• That it contains residual sugar for the yeasts to produce CO₂.
• That the temperature is above 18°C.

If any of the three is missing, there is no gas.

How to prevent kombucha from continuing to re-ferment in the bottle

There are three solutions used by different brands:

• Pasteurise: some brands kill yeasts and bacteria to stop fermentation. The problem: the probiotic properties provided by these live microorganisms are lost.
• Low residual sugar: this is the case for Mūn Kombucha. Our kombucha has just enough sugar to generate a little fizz. Once the remaining sugar is consumed, there is no fuel left for further fermentation. This is why Mūn Kombucha is stable at room temperature and does not require pasteurisation.
• Refrigerate: this is the most common solution. If kombucha has live yeasts and a lot of residual sugar and is kept at room temperature, fermentation will continue until the sugar is exhausted. Above 2 g/100 ml, this second fermentation can cause the bottle to explode. This is why kombuchas with a lot of residual sugar are always kept cold.

Does Mūn Kombucha have gas?

As a general rule, yes, but with nuances. At Mūn, we brew following the traditional method with over 2,000 years of history. We use natural, premium quality and 100% organic ingredients. We do not add CO₂: the gas present in our drinks is natural and is generated during the second fermentation.

In the first fermentation, which we carry out in open tanks covered with cloth, the yeasts work with the sugar and produce CO₂ which escapes into the air. When we consider this first fermentation to be complete, we bottle the kombucha and add the flavouring juices: fruit juices (apple, pomegranate, lemon), root juices (ginger, turmeric), leaf juices (mint, basil) or vegetable juices (cucumber, beetroot).

This flavoured kombucha is bottled in glass bottles and left to rest. As we do not pasteurise the kombucha, the yeasts remain active and ferment the sugars from the juices. The CO₂ generated results in the characteristic fine bubbles.

Do all Mūn varieties have the same fizz?

No. The Natural (Casual range) or Original (Premium) varieties, having undergone a very long first fermentation, have virtually no residual sugar. As they do not contain added fruit juice, they do not have that extra sugar for the yeasts to generate fizz. These varieties develop a very fine carbonation over time, but it is common for them to have almost no bubbles.

The other varieties (with fruit or root flavouring) usually have more perceptible gas, although it also depends on other factors. Temperature influences this: in winter, yeasts are more dormant and gas production is lower. If you receive a batch with little gas, you can leave the bottles at room temperature for a few days to encourage the natural process.

Our production is entirely natural, so it is normal for there to be some difference in gas produced from one batch to another. The benefits of drinking kombucha are independent of the fizz: what matters is the process that occurred during the first fermentation.

Can gas be added to kombucha?

Yes, it can. This is what other brands do: to avoid relying on the natural process, they add industrial carbonic gas. This ensures that their kombuchas always have exactly the same level of gas. These more processed kombuchas always have the same carbonation, unlike Mūn Kombucha, where each variety and each batch are slightly different.

Is added carbonic gas healthy?

Added carbonic gas can cause problems in people with digestive ailments such as dyspepsia, gastritis, gastroesophageal reflux, or irritable bowel syndrome. In the case of kombucha made according to the traditional method, without added gas but with that generated during fermentation, the digestive aid factor provided by natural probiotics and enzymes present in the drink should be considered. If you are unsure whether it will suit you, you can let the gas dissipate before drinking it, add ice, or serve it patiently.

In the case of added CO₂ — such as that in soft drinks or processed kombuchas — the aforementioned benefits are not present, and it could worsen or even cause digestive problems.

Does the use of added CO₂ have to be labelled?

Yes. According to the Regulation (EU) No 1169/2011, carbonic gas is an additive considered an ingredient and, therefore, must appear in the list of ingredients on the label. If a kombucha contains added CO₂, you will find it indicated. If it does not appear, the gas is natural.

Frequently asked questions