How to Increase Yeast Populations in Kombucha
Do you think that the yeast population in your kombucha is low? In this post we take a look at how to check the yeast levels, the problems that low yeast levels can bring, and how to boost these levels.
One of the key elements to maintaining consistent and good results in your kombucha making, is keeping the balance balance between the yeasts and the bacteria in the kombucha and starter liquid.
A balanced microbial component between these two colonies will mean that you get well rounded kombucha and hassle free brewing.
This balance can be affected by ingredients, temperatures and brewing practices. Usually it is the bacteria which end up on the low side, as yeasts can tend to build up and dominate. There are occasions however where the yeasts are the ones who become out competed by the bacteria.
Below we will take a look at how you can step in, and encourage those yeast friends to multiply and get back into balance with bacteria. But before we do that, let’s take a quick look at how to gauge whether the yeasts are low, and what kind of brewing problems this can cause.
How to Know Your Kombucha Yeasts Are Low
If you are not sure whether your kombucha yeast population is low, then you will be relieved to know that checking this is super simple.
What the Yeasts Look Like
Kombucha yeasts show up as brown string like colonies. They are either lightly attached to the SCOBY, or free floating. Besides the brown strings, sediment ‘dust’ like brown matter is also a form of yeasts. This can either float around, or collect on the bottom of your brewing container
If You Do Not See Much of This, The Yeasts Are Low
If you cannot see much in the way of brown strings, or even yeast sediment – then you know that your yeast populations are down.
Kombucha Brewing Issues Which Can be Caused by Low Yeast Levels
Here are some of the brewing issues which are usually directly related to low yeast levels.
Ferments That Take Forever
The yeasts are the ones which kickstart the fermentation. Without them ferments are apt to not get off the ground properly, or take a very long time to mature – even if temps are warm.
Lack of Carbonation
The yeasts are the guys which produce carbon dioxide and carbonation in kombucha. If there are not enough of them around then you will most likely experience low levels of fizz.
Deterioration in SCOBY Growth
If yeast levels get critically low, this will impact the bacteria populations as well. The bacteria depend on the yeasts to convert the sugar into a food source which they can take up. If there are not enough yeasts around for this – then you will find that the bacteria suffer as well. The bacteria are responsible for thickening and growing the SCOBY. So if the SCOBY is not growing in any way, and new babies at the surface take a long time to develop – this is another problem which is indicative of critically low level of yeasts.
5 Ways to Increase Yeast Populations
As you can see, it is super important to keep the balance between the microbes. Here are four things you can implement to encourage the yeasts and get them flourishing once more.
# 1 Raise the Temperature
One of the first things to check when you think that the yeasts are in decline is the temperature.
Kombucha does best when brewed between 69-84 degrees. The bacteria prefer the lower end of this scale and the yeasts prefer the higher end. In other words they like it warm! So consider the temperature at which your kombucha is brewing at. Is it pretty low? Is it even right out of this range of suitable temps?
If so, then a really good way to encourage the yeasts is to raise the temperature a bit. The best range to keep it in for encouraging and resuscitating the yeasts is 75-84 degrees.
How to Raise the Temperature of Your Kombucha
There are a number of different tricks one can implement to raise the temperature of your kombucha. The one you choose should depend on how many degrees you need to increase by.
Find a Warmer Brewing Place
First up is to check to see if there is a place in your house to brew your kombucha which is warmer than where it is presently. Warm spots can include close to the back of refrigerators (where heat is produced), close to entertainment systems which heat up at night, or simply in a room on the sun side of your home. Just be sure that you do not put the kombucha in direct sunlight as this can harm it and the SCOBY. If you only need to raise the temperature of your brew by a s couple degrees, simply moving it to a warmer location can do the trick.
Use an Electric Blanket
If however you need to raise the temperature of your kombucha by quite a bit, you might need to use artificial heating. One way to do this is to use an electric blanket. Wrap it around your kombucha and set it to the lowest setting. If that setting is not low enough, you can also try to make a ‘tent’ out of it. This way the blanket does not touch the kombucha and end up overheating it.
Use a Kombucha Warmer
If you do not have an electric blanket – or do but need it for yourself! – then a good buy is kombucha warmer. These are specifically designed for kombucha and have super fine settings to make sure that you can brew your kombucha at exact temperatures without overheating it.
For more detailed info on keeping kombucha warm, check out How to Brew Kombucha in Cold Weather.
# 2 Use Starter Liquid Rich in Sediment
The next very effective way to encourage the yeasts is to use starter liquid which has as much sediment in it as possible. The reason for this is that that sediment is free floating yeasts. Incoporating as much of this into your starter liquid means that you are injecting each new batch of kombucha with an inoculation of free floating yeasts.
The bacteria are concerntrated in the SCOBY, which you place into each new batch of kombucha. Because yeasts tend to be free floating, it is important to make sure that when you set up a new ferment you are including as much of these as possible. This is just as important as putting the SCOBY in!
How to Get Yeast Sediment Rich Starter Liquid
If you take a close look, you will see in whatever kombucha you are using as your starter liquid that the sediment collects at the bottom. The first step to harvesting this is to disturb at as little as possible beforehand.
The best way to harvest the sediment heavy liquid from the bottom on the container which the starter liquid is in is to syphon it out. For this you will need either a proper syphon or simple piece of hose. A ready made syphon will allow you to pump out this liquid. If you are using a length of hose, then you will have to place the vessel on a table. Insert the one end of the pipe and suck on the other end. As soon as the liquid rises in the pipe over the rim of the vessel, transfer your end of the hose into a container to catch the flowing starter liquid.
If you do not have the yen to do any syphoning, then you can also do the following. Scoop gently out all of the top liquid. Once you get to the bottom, you can pour this out into your brewing vessel. If you do the scooping slowly enough, it shouldn’t disturb the sediment at the bottom too much and you should be able to harvest most of it.
Use Starter Liquid from Your SCOBY Hotel
SCOBY hotel’s are a super potent source of starter liquid. They will most probably contain a lot of sediment, and even some yeast strings of you are lucky. If you have not started a SCOBY hotel, then check out our post How to Make and Maintain the Perfect SCOBY Hotel for more info. Having a SCOBY hotel is very important because then you always have back up cultures on hand!
# 3 Do Not Wash Your SCOBY
If you are in the habit of washing your SCOBY – stop this! It can be tempting to give your SCOBY a rinse between brews in water – but this can be very detrimental. In fact it could be a main cause of the low yeast levels. If there are any brown strings attached to the SCOBY before washing, chances are that they will be washed of during rinsing. And these strings are what we want!
# 4 Use Less Sugar
If you are using more that the standard 1 cup of sugar to 1 gallon of tea, then you should drop the quantity to that or just below. While it would seem that lots of sugar would stimulate the yeasts as it is their food source, the opposite can actually happen. Too much sugar can have the effect of putting the yeasts into stagnation.
# 5 Use More Black Tea
If you have been using green tea or some other alternative to black tea, try switching back to black tea for a few brews. Black tea has a high concentration of tannins – which is nourishing to the yeasts.
Once you get an idea of what the yeasts like and what boosts them, upping their numbers and vitality is not difficult. Keeping your culture and kombucha in balance microbially is the best way to ensure hassle free ferments, and perfectly brewed kombucha.
On this note, while it is important to get the yeast numbers up if they are low, be careful not to swing to hard in the opposite direction. Usually it is the yeasts which are outcompeting the bacteria, and it does not take much to stimulate them. So keep in mind while you are getting their numbers up that there will be a point where you do not want to encourage them any further.
This all might sound like a lot of work, but if you keep an eye on your ferment and regulate the relationship between the yeasts and the bacteria, you will probably find that you end up with effortlessly good kombucha.