Kombucha Second Fermentation (4 Common But Crucial Mistakes & How To Avoid Them)

What is Kombucha?

Kombucha is made by fermenting sweetened tea using a "symbiotic culture of bacteria and yeast" or scoby as it's affectionately called. (a horrific looking alien lifeform that wallows around in the tea eating the sugar and turning the liquid sour). The resulting liquid is then sweetened and flavoured with fruits, ginger and anything else you want to try.

Like beer it is often done in 2 stages, the initial primary fermentation (which in beer is used to convert sugar to alcohol) is used in kombucha to convert the sugar to vinegar while letting the produced CO2 escape.

The kombucha second fermentation stage happens after removing the scoby and adding some more sweetener and flavours before sealing the liquid in a container so this time the produced CO2 is absorbed into the liquid, carbonating it.

Kombucha is a source of probiotics and antioxidants that reduces the risk of heart disease and supposedly can prevent some cancers. No wonder the beverage developed into one of the most popular health drinks over the last decade. The downside - if kombucha isn’t made properly it doesn’t only lose its promised advantages, it can even become dangerous for consumption.

A main contributor to the rising popularity of the beverage is the fact that it can easily be made at home - by anyone. It’s uncomplicated and doesn’t take much effort once you get the hang of it.

Kombucha lovers started to prepare the drink in their own kitchens and SCOBY (a symbiotic growth of acetic acid bacteria and osmophilic yeast species) made their way into private homes.

Unfortunately soon after the introduction of kombucha into non-commercial kitchens, the hip-drink was hit with a lash-back and the doubt around the alleged health benefits started to evolve into actual concern.

Dangerous mold appeared in the ceramic fermentation bowls and unwanted bacteria contaminated the drink between first and second fermentation. These practices caused a poor reputation for home made kombucha.

Most mistakes are made in the steps between primary and second kombucha fermentation

Kombucha has two fermentation states. First fermentation is the basic process in which tea is fermented for up to two weeks in order to produce Kombucha. For carbonation and to create the desired flavour, second kombucha fermentation comes into action. This step is usually carried out by adding fruit and sugars to the liquid and filling it into bottles.

Bottling kombucha comes with obstacles. Here are the most common mistakes made when brewing kombucha and tips and tricks on how to successfully do a second kombucha fermentation.

Mistake 1: Bottling uneven amounts of fruits and sugars

In order to produce an even batch of kombucha, the amount of fruit and sugar that goes into each bottle has to be exactly the same in all of them. After fruit and sugars get added to the kombucha, everything should be stirred and mixed thoroughly. While bottling the mixture, naturally the bottles will contain differing amounts of sugars and fruits. It’s tricky to guarantee exact same amounts for each bottle. However, filling varying amounts of sugars and fruit into each bottle causes the contents to ferment at a different speed and intensity and will hence generate an irregular batch. Using fruit purée instead of fruit chunks will help to spread fruit more evenly throughout the liquid.

Mistake 2: Unknowingly contaminating the kombucha batch

Fermentation is the chemical transformation of material using bacteria and enzymes. Even though some bacteria are necessary for brewing kombucha, not all kinds are welcome during fermentation. Using vessels that aren’t airtight and sanitised can cause bacteria to enter. The consumption of contaminated kombucha can cause side effects like stomach problems, yeast infections and allergic reactions.

It’s crucial to prioritise the cleanliness of the process and sanitise bottles inside out before bottling. Accidental contamination is the main reason for a batch to taste bad and spoil. Even the smallest contamination can cause your bottled kombucha to go off and make it unsafe for consumption.

Mistake 3: Using bottles that aren’t pressure proof during second kombucha fermentation

Especially for inexperienced brewers, fermenting in a glass container can become dangerous, . However, the ability to increase pressure in a vessel is key for the success of second kombucha fermentation. Unsuitable containers can crack, break or even explode if the contents ferment at room temperature for too long. As mentioned before, the fermentation time per bottle can vary, depending on the amount of flavouring fruits and sugars that have been added. For safety reasons, it is recommended to ferment bottles inside of closed cupboards or build a shield in case the bottles break or explode.

Mistake 4: Getting fermentation times wrong

After the initial fermentation which typically takes between 7-12 days, the batch of Kombucha is fermented in bottles at room temperature. This takes something between 2 to 10 days. Once the desired fermentation and carbonation state is achieved, the bottles are refrigerated in order to prevent further fermentation. Even though Kombucha is a fermented beverage, contrary to common belief it cannot be stored at room temperature. Fermenting too long can cause the vessel to break. Not fermenting long enough will leave the beverage rather flat and tasting bland. Fermentation times depend on how much of which fruits and sugars are used and are also highly sensitive to the surrounding temperatures. More sugars, fruit purees and a higher temperature generally speed up the process of second kombucha fermentation.

Eliminate mistakes during second kombucha fermentation in one go

We recommend using a kombucha brewing jar that is pressure rated to much higher than that produced during fermentation, like the fermenter king junior. It doesn’t only allow you to brew bigger batches at a time (up to 18L) but it also serves as an ideal container for both primary and secondary fermentation.

When using a fermenter king junior or even larger pressure fermenters the carbonation that usually requires a second kombucha fermentation can be achieved by using the gas from first fermentation.

You’ll save time and effort, as you no longer need to clean, sanitise, fill and cap all those bottles. Nor do you have to wait for a second fermentation to carbonate them.

An adjustable pressure release valve on the fermenter holds in the CO2 produced and releases any pressure in excess of exactly the amount you need to carbonate the kombucha perfectly. This means the entire batch is carbonated to exactly the same level every time and it can be adjusted if it is over or under carbonated by adding CO2 from a gas bottle or releasing excess pressure.

Adding an external source of CO2 not only means you can adjust the carbonation level to exactly what you desire, it can also be used to push the finished kombucha out through a tap! Kombucha on tap at home is easy, much easier than bottling!

The whole batch will come out more regular as all the ingredients used for second fermentation of kombucha are evenly spread in the vessel throughout the flavouring process. The pressure proof fermentation system allows you to brew kombucha without the worries of shattered glass and broken vessels.

Easy tap systems allow you to pour your ready made drink directly from kombucha brewing jar into a glass - ready to enjoy. Bottling becomes unnecessary. But you won't only save time and effort using an all-in-one fermenting system. Our fermenter king junior also eliminates the possibility of contamination with bacteria and creates a cleaner, more regular product that is completely safe to consume.