It happens to all of us, you push the boundaries of your brew length only to discover your brew has turned to vinegar.
What’s there to be done? Can it be saved?
Luckily, there are a few different tricks you can try to help recover your brew. If it’s beyond saving, then I’ve also provided a few suggestions to help things not go to waste.
First, let’s cover why your kombucha is smelling like vinegar.
Why Your Kombucha Smells Like Vinegar
There are two main stages of kombucha development – aerobic fermentation and anaerobic fermentation. The aerobic fermentation is the first to occur.
This is when the healthy bacteria start to grow and multiply. They start eating the fuel and minerals in your sweet tea and as a by-product, they produce healthy acids. The most common acids in kombucha are:
It’s the acetic acid that produces this vinegarly flavour. In the right balance, it’s key to producing the unique kombucha flavor.
Pro TipIt’s the acetic acid in the kombucha that causes the vinegary taste and smell
However, if you let things become unbalanced the vinegar taste (and smell) becomes overwhelming.
As the bacteria grow and develop they begin to weave the cellulose network that eventually forms the child SCOBY. Once fully formed, this child SCOBY cuts off the supply of oxygen and the anaerobic fermentation begins.
This is when the yeast take center stage. They begin devouring all of the sugar in the sweet tea – turning it into alcohol and carbon dioxide (both crucial to the taste profile of kombucha.)
Now, normally we try and stop this fermentation stage before all of the sugar is digested. This is why we regularly sample the kombucha when we are new to know when it’s time to start the secondary ferment.
Fun FactThe levels of acetic acid in kombucha rarely go above 2%. U.S. regulations requires true vinegar to be at least 5% acetic acid.
But, if we mistakenly forget about the brew, or just try and push the timeframe, the yeast may digest all of the sugars in the brew. Once the sugar is digested they begin to enter a dormant phase where they aren’t producing alcohol or CO2.
The bad news is there is nothing like sugar to regulate the bacteria. So they will continue to produce those healthy acids until they completely take over the brew.
This is likely why your kombucha smells like vinegar – too much acetic acid!
Typically, the Kombucha ferment will have about 30% more gluconic acid than acetic acid. If one of your bacteria cultures is too weak then your kombucha may become unbalanced (this is usually the case if your brew is turning to vinegar after 2-3 days.)
How You Can Fix Sour Kombucha
Fixing a batch of kombucha that has turn to vinegar will never be perfect. If you understand why it’s turned to vinegar then you’ll understand why.
It’s difficult to remove the acetic acid! It’s a similar predicament to over salting food – the best way to fix it is to add more of the other ingredients.
1. Add More Sugar
Depending on how vinegary your brew is, you may get away with just adding more sugar to the brew.
Try pouring a glass of the vinegary kombucha and then begin adding sugar slowly. Taste as you go to see the effect of the added sugar. If you’re lucky, you can rebalance the taste profile with the right amount of sweetness.
If this works, then just add the sugar to the entire batch and move on to the second ferment.
Remember, you always want the kombucha going into the second ferment to be a little sweet to get the best carbonation possible.
2. Dilute With Water and Add Sugar
If the brew still tastes too vinegar you may want to try diluting the brew a little with water.
Use the same method as mentioned above – first pour a glass of kombucha so you can experiment without completely ruining your entire brew.
Slowly add water and sugar to the cup. Everyone’s level of vinegar is going to be different so it’s difficult for me to suggest precise amounts. Just trust your own taste buds to find the right balance.
Once you find a happy medium you can begin doing the same process with your original batch.
3. Blend With Fruit Juice
If just adding sugar, or diluting with water isn’t working, try blending the kombucha with some fruit juice. Following the same methods above, test in smaller batches before you commit to the entire brew.
The style and stage of brew – batch brew, or continuous brew – will determine how much fruit juice you will need to put in.
If you are still on your first ferment or are in the early stages of the continuous brew, you want the kombucha to be a little too sweet for your taste buds. This is how you’re going to get the high levels of carbonation you’re looking for.
4. Add Calcium Carbonate or Baking Soda
Adding calcium carbonate and potassium bicarbonate has been suggested by some in the brewing community (to be honest, I haven’t really tried it myself.)
Both of these substances will neutralize some of the acids – but the downside is they may leave unwanted byproducts that can impact the taste.
You can buy calcium carbonate supplements at your local supplement store – just be conservative when adding it to your brew. The reaction between calcium and acids usually produces foam and can sometimes leave a chalky after taste.
If you don’t want to buy supplements you can try using eggshells. They are high in calcium and can be easily removed once the reaction is complete.
Alternatively, you can try adding a little baking soda into the mix. The acids will react with the potassium and create potassium bitartrate – otherwise known as cream of tartar.
Using baking soda will result in crystals that eventually fall to the bottom and can be removed. The major downside to this method is it takes some time (can be up to 30 days.) Make sure you refrigerate your bottles while you’re waiting.
5. Chill Your Kombucha For 3 Weeks
As a last resort you can try and chill your kombucha in the refrigerator for 3 weeks. This is sometimes called cold stabilization or chill proofing.
It usually helps to mellow out a kombucha with lots of bite and will help smooth out the flavor.
Just keep in mind that this isn’t a drastic solution and will only smooth out the flavor – don’t expect a complete re-balance.
How To Prevent Your Kombucha From Becoming Too Sour
Most of the time a sour tasting brew comes down to timing. But there is the odd case where the brew timing was perfect and it still turned into vinegar.
Let’s talk about both.
Timing Is Everything
In regular conditions the primary ferment should take 7-8 days. The temperature should be between 68-78°F. Remember, you want the brew to taste a little sweet before the secondary ferment.
If you’ve forgotten your brew and have left it for over 10 days then it may be turning into kombucha vinegar. Properly fermented Kombucha should be between a pH of 4 and a pH of 2.
Anything below 2 will be too sour to drink. You can measure the pH using little pH strips (you can buy them from Amazon.)
You can try some of the suggestions above, or you can just leave the brew for another 5-7 days and wait for it to turn completely sour.
Then, once the brew is completely sour, use it as a source for your next starter liquid. The stronger the starter liquid the better!
This time, keep a close watch on your brew. After 5 days you can begin sampling the brew with a straw. With time, you will know the exact flavor required for your perfect brew!
Use The Standard Ingredients
If you’re still new with brewing kombucha, I recommend you stick with what has been proven to work.
This means using the right tea (stick with black tea if you are unsure,) the right amount of sugar, the correct starter liquid, a SCOBY, the right brewing temperature, as well as brewing lengths.
If you try to change things too soon without having backup SCOBYs in your hotel you could potentially knock things out of balance and end up with weak bacteria.
Remember, having a balance of the right bacteria is key to preventing your brew from becoming too sour too quickly.
Keep Things Balanced
One reason for things going sour too quickly is overly active yeast. If your brew has gone sour after 2-3 days this may be the case.
The remedy is as follows:
- Reduce the temperature of your brew
- Clean off your SCOBY before placing it into the vessel
- Use a weaker sweet tea
- Use starter liquid with less yeast
Reduce The Temperature Of Your Brew
The amount of yeast production is directly linked to the temperature. If you want to slow things down – reduce your temperature. If you want to speed things up – increase it.
This is why brews usually take longer during the winter months.
If you’re brewing during the summer and your kombucha is always in a hot environment you may want to consider storing it in a dark basement where the temperature won’t be so high.
Clean Off Your SCOBY
Notice the brown strands of yeast on your old SCOBY? If your kombucha is turning to vinegar too fast you will want to remove as much yeast from the SCOBY as possible.
Just scrape these strands of yeast off before you place the SCOBY into your next batch. This will help reduce the yeast load and hopefully slow things down a bit.
Use A Weak Starter Tea
If you provide lots of sugar and nutrients from the tea the yeast is going to take off like a rocket! If you want to slow it down, try using a less strong starter tea.
Experiment with using less tea when you brew your sweet tea as well as reducing the amount of sugar you are using.
I’d recommend trying this only as a last resort, as it can potentially unbalance things even further.
Use Starter Liquid With Less Yeast
Instead of taking your starter liquid from the bottom of your SCOBY hotel, try taking it only from the top.
Old yeast sinks to the bottom of the hotel and becomes dormant until woken up with new sugar. As you can imagine, the liquid from the bottom of the hotel is going to be much more potent than the top.
Combining a few of the above suggestions will hopefully stop your brew from turning sour too quickly.
What You Can Do If Nothing Is Working
If nothing seems to be working I’d recommend getting a new SCOBY and new starter liquid from a friend and starting fresh.
In a sense, completely hitting the reset button. It can be tough sometimes to diagnose what exactly is causing the imbalance. Sometimes it’s easier to just start with a fresh
But that doesn’t mean you have to throw out your kombucha. Here are a few ideas of what you can do with your new kombucha vinegar!
Turn It Into Real Kombucha Vinegar
If you let your brew sit for another 30 days it will eventually turn into real kombucha vinegar. This can be used for many different applications. Here are a few ideas:
- Use it in place of regular vinegar i.e. in a vinaigrette
- Use it as a cleaning fluid
- Use it as a marinade
- Use it for extra strong starter liquid
Simply store the vinegar in a new bottle and use it in place of your regular vinegar. Note, it will have a slightly different taste profile – it’s worth tasting at least once. Everyone needs to experience the kombucha face!
If you’re feeling adventurous I recommend splashing some on some vanilla ice cream!