11 Important Things To Know for a Successful Kombucha Brew

Make your kombucha brewing a big success! Here is the best guide and a deep dive into the fermentation process of kombucha.  

I will share the 11 most important questions I have asked during my kombucha brewing journey.  Furthermore, I will also share the answers and lessons learned I gathered from my experience, experimenting, and learning from others.  This list is all about making your kombucha’s 1st fermentation as successful as possible.

Kombucha’s 1st fermentation is the process of turning sweet tea into tart kombucha through fermentation by the kombucha culture. Whilst kombucha’s 2nd fermentation is the process of creating various flavour infusion and carbonation by letting kombucha continue to ferment with additional ingredients in a tightly sealed bottle. Before you can 2nd ferment your kombucha, you need to complete the 1st fermentation first.

If you haven’t heard that kombucha is beneficial for you, here is an article on the health claims of kombucha. I have also included a basic recipe and instruction at the end of this article for those who are new at kombucha brewing. If you would like to read more on the chemistry of kombucha brewing, here is a great article from which I learned a lot.

I love to hear how your kombucha fermenation is going!  If you have any good brewing techniques, questions, or opinions differing from mine, please share in the comments below, because they will most likely help a fellow fermenter!

1. What exactly should the starter to sweet tea ratio be?

Mature kombucha starter to fresh sweet tea ratio should be no less than 1:10. Kombucha brewing is not an exact science. If your recipe is slightly off, your brew will still be most likely successful. This explains why everyone’s brewing instruction and recipe seems to be a little different.  And that’s ok!  The time for caution is when you see a recipe calling for a starter-to-tea ratio below 1:10. Then, you are risking the acidity level being too low and kombucha growing mold. Let me give an example:

• 1 cup of starter, 8 cups of fresh sweet tea, i.e. 1:8 of starter-to-tea ratio: this is a safe recipe to use. In fact, if you like to add 8 cups of starter to 1 cup of fresh tea, it’s totally fine and nothing can go wrong with it. Expect your brew to finish in no time!
• 1 cup of starter, 16 cups of fresh tea, i.e. 1:16 of starter-to-tea ratio: this is not a safe recipe to use, proceed at your own risk.  There is a higher possibility for contamination.

Now you know the guideline for starter-to-tea ratio, you can adjust the recipe to work for the size of your container and the amount of ingredients you have.

2. Do I need a SCOBY to make kombucha?

It’s definitely nice to have a SCOBY, but not mandatory. SCOBY (symbiotic culture of bacteria and yeast) is the byproduct of kombucha fermentation, grown from the bacteria and yeasts existing in kombucha, and shaped like a flat piece of jelly. Think of the SCOBY as a living hotel of the various bacteria and yeast. It gives a boost of strong culture so the tea ferments faster. SCOBYs are usually stored in a starter liquid, which is just mature acidic kombucha.  Without a SCOBY, you can still ferment the tea with just a starter (mature acidic kombucha), but at a somewhat slower speed.

A mature acidic kombucha, as the starter liquid, contains the full range of bacteria and yeasts, which is why many people are able to grow a SCOBY from a bottle of store-bought kombucha without a SCOBY.  Comparing the starter to SCOBY, sufficient amount of starter is definitely more important than the SCOBY towards the success of kombucha brewing.  You can brew kombucha without a SCOBY, but you can’t without a quality starter liquid.

3. Can I feed my kombucha brew something other than black tea and white sugar?

YES, and keep in mind the following. If you are talking about brewing the kombucha in a blend of black and green tea, and organic cane sugar, then that’s super healthy for the SCOBY and culture growth. This is the combination I use, as I found that green tea produces very beautiful and dense SCOBYs for me, and black tea gives a nice aroma to the kombucha. I use organic cane sugar because it’s minimally processed while still providing the form of sugar easily digestible by the microbes.

If you are considering using coconut sugar and liquid sweetener and non-caffinated herbal tea along with other spices and plants, know that some of the ingredients may inhibit the growth of SCOBY and culture, or provide insufficient nutrients.  Just like cooking anything else in the kitchen, experiments are fun! Hope you would agree with me on this – the top benefit of brewing your own kombucha is that you get to create what suits your taste. So play with kombucha fermentation with the extra SCOBYs. Remember to always save at least one uncontaminated SCOBY and starter, so you know you are covered if anything goes wrong with your kombucha brewing experiments.

4. Does the shape of my kombucha brewing vessel matter?

Yes, it does! Kombucha culture thrives in an environment where there is a large surface area, and the depth of the tea is roughly the same as the diameter of the tea surface. A lot of breathing room provides oxygen that feeds the growth of the bacteria and yeast, and makes the fermentation go faster. Most of us probably don’t give a second thought when picking up a big tall mason jar and filling the brew to the rim. Not to say you can’t ferment successfully in a tall jar. However, if your kombucha brewing seems to be sluggish, try switching to a wide jar, or fill the tea only half way.

5. What is the better indication of kombucha doneness: SCOBY thickness or fermentation time?

Neither. The best indication of kombucha doneness is by tasting. It’s done when you like the balance between the sweetness and the tartness. Sometimes the SCOBY grows very thin. Depending on the temperature and season, kombucha brewing time can vary from days to weeks to reach the taste you desire.

6. Should I feed more sugar to my kombucha brew if I need to stimulate the yeast growth?

It depends, but not too much at once. There are other options as well. Kombucha is a living thing, that relies on the balance of bacteria and yeast. Once in a while you will experience a slowing of yeast activities, especially in the winter. Although you will want to ferment the kombucha for a second time to achieve good carbonation (more on this in Kombucha Carbonation and Flavouring Tips: The Second Fermentation), at the end of the 1st fermentation, the yeasts in the kombucha are already producing fizz and bubbles. If the yeast activities are weak during the 1st fermentation, you will likely have a hard time producing carbonation during the 2nd fermentation as well.

To stimulate yeast growth, the automatic thought process is that sugar feeds the yeast, therefore adding more sugar to the brew can give the yeast extra food source. However, too much sugar at once can make the yeast stop re-producing (a.k.a. the “crabtree effect”). A common technique to stimulate yeast growth with sugar is to feed the brew with less sugar to begin with, and add more sugar over a period of a few days. Other tricks that I have used are:

• making a stronger tea that contains more caffine to stimulate yeast production.
• increasing the temperature of the environment as yeast loves the temperature in the high 20’s ºC.
• using the bottom portion of the previous brew as the starter for the next brew, as more yeasts exist in the bottom portion.
• using older SCOBYs that contain more brown yeast strands in the next batch of fermentation.

7. What do I do if there is too much yeast in the kombucha?

Do the opposite of raising the yeast ratio to reduce them.  Just as not having enough yeast activities, there will also be times when there is too much, especially in the summer. When the yeasts are too active producing lots of carbonation, they will also compete with the bacteria for nutrients.  Therefore, it’s important to keep the yeast in check in the hotter months. To reduce the yeast and bring a balance, you can try the following methods, such as:

• make a weaker tea by simply using less tea leaves.
• place the fermentation vessel at a cooler spot between 20º and 25ºC.
• use the newest SCOBYs that contain less yeast (the brown strands).
• filter out extra yeast strands from the starter liquid.
• use the top portion of the previous brew as the starter for the new brew, as the top portion contains more bacteria and less yeast.

8. Is my kombucha culture still alive in the winter?

Kombucha brewing can be really slow in the cold winter months.  Sometimes the fermentation is so slow to the point that you wonder if you have the patience to wait to drink this batch, or rather your kombucha is actually dead.  In fact, it’s just the seasonal effect, especially if your house is on the colder side.  Keep in mind, it’s completely normal to have a few really slow kombucha brewing months (3-4 weeks of brewing cycle) and fairly flat kombucha (even with 2nd fermentation).

A few times I found myself worrying about my kombucha, yet my worries always turned out to be unnecessary.  My advice – have faith in the little creature you are caring for! Find a warmer spot or an extra heat source for it in the house. Most of all, keep brewing and give it time, even if there seems to be very little SCOBY forming.  Your brew will often pick up pace as the weather gets warm.

9. Should I cover the SCOBY hotel with a lid or a towel?

Either is fine; but my clear preference is to cover the SCOBY hotel with a towel (or equivalent breathable cover).  SCOBY hotel is the container that stores your extra SCOBYs and starter liquid (mature kombucha).  Whether to cover the hotel with a lid or a towel – seems like the opinions are split on this one.  Therefore, I have tested both and found that the SCOBY from a lid-covered hotel is more often in a deep hibernation, and the bacteria is more dominant over yeast.  In contrary, the SCOBY from a towel-covered hotel is easier to re-activate in my experience.

In addition, I can expect the towel-covered hotel to grow an extra SCOBY for me.  Although I don’t need any more SCOBYs, it’s a price I am willing to pay to keep my SCOBYs more “awake”.  Seems like by keeping the hotel breathable, the yeast and bacteria are more in balance with each other.

10. Should I store the SCOBY hotel in the fridge?

No. The  SCOBY hotel should be stored in room temperature.  The most optimal temperature for kombucha culture is between 21º and 29ºC. Instead, temperatures much lower or higher, will damage some or all strains of the microbes in kombucha and the SCOBYs. Therefore, the SCOBY hotel should never be stored in the fridge. If the harmony between yeasts and bacteria is broken, the kombucha and SCOBY may fail to culture the tea ever again.  Similarly, the SCOBY and starter should never be added to hot tea either – remember to always let the tea cool to room temperature before mixing with the culture.

11. Should I brew my kombucha using a continuous brewing vessel?

The continuous kombucha brewing method uses a container with spigot. You can easily release mature kombucha from spigot, while adding fresh sweet tea to the top of the container at any time.

Pros of Continuous Brew

The biggest pros of this method are the convenience in kombucha brewing and a continuous supply of kombucha. In addition, there are also some reported health benefits associated to this method due to the existence of microbes in different stages of fermentation.  I believe the continuous brew is also a more traditional way of fermenting as it meets the needs of daily consumption and ad-hoc replenishment.

Cons of Continuous Brew

Some of the cons of this method are the extra work of cleaning the spigot as it possibly being clogged by dead yeasts residuals in the kombucha, and the less control over which part of the brew I pick up the starter from – in this case the remaining kombucha because I will always remove the bottom portion of the kombucha from the container.

How I Brew My Kombucha

Despite the advantages of the continuous brewing method, I chose not to use it. For me, I rarely drink my kombucha straight after the 1st fermentation. Instead, I always bottle my kombucha for a second fermenation. I don’t feel I can fully take advantage of the readily available kombucha on a tap, rather I prefer not to clean the spigot and have more control over kombucha brewing. For example, when I want to use the bottom layer of my kombucha as the starter for the next batch. I hope the pros and cons help you to determine if the continuous kombucha brewing method is right for you.

Related: More Fermentation Recipes You Will Love

• Wild Fermented Salsa (No Whey, Probiotic, Vegan)
• Fermented Pickles /w Green Tea and Dill Flowers
• Homemade Fermented Sauerkraut /w Caraway Seeds
• Pineapple-Turmeric-Ginger Probiotic Sauerkraut
• Paleo Apple-Fermented Kimchi
• Keto Kimchi (Whole 30, GAPS, Paleo)

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