Kombucha And PH: The Complete Guide To Raising And Lowering PH – Grow Your Pantry

Kombucha And PH: The Complete Guide To Raising And Lowering PH

by Susan Grey on September 17, 2019
Kombucha_and_ph_illustration

 

pH and kombucha have a significant relationship. pH is an essential measurement when brewing kombucha, for it is a central indicator to whether your brew is safe to drink or not - also being indicative of the taste too.
By understanding what pH is and how to influence the pH you will be able to safely brew kombucha without the worry of unwanted bacterial growth.
When starting the ferment, it is essential to test your pH. We would recommend to aim for 3, with 2.5 - 4.2 being considered a safe range. 
Low pH levels kill harmful bacteria while keeping the healthy bacteria and SCOBY alive. This allows us to get all of the probiotic nutrients without any danger. The higher levels of pH could become a breeding ground for unwanted growth. 
By guaranteeing that the brewing environment is within this safe range, it ensures no diseases breed and contaminate your batch.
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What Is pH?

[Warning - Technical!]
"The pH value of a drink is a direct function of the free hydrogen ions present in that drink". In layman's terms: every liquid has a certain number of free "ions" or you can think of them as particles. The more free ions in a liquid, the more acidic the liquid. The more acidic, the lower the number on the pH scale. 
For example, vinegar has many free ions so it's more acidic and in turn has a pH of 2.4.
The scale which they're measured in is logarithmic, or you could think of it as, the closer to 1 it gets the more extreme it gets and the closer to 14 it gets the more extreme it gets. 
If you don't quite understand this point, don't worry it isn't necessary to make excellent tasting kombucha!

pH In Perspective

To show how the pH of kombucha compares to other common beverages, we've created a table to demonstrate the relative values of it. Most of the drinks we consume are within the specified range for our consumption.
Beverage
pH Value
Your Kombucha Brew
2.5 - 4.2
Coke
2.52
Water
7
Vinegar
2
Milk
6.5
Breakfast Tea
6.3
Starbuck’s Coffee
6
 

Ingredients And Their Influence On pH

Every ingredient in kombucha will affect the pH. To get the right pH it's necessary to know how each ingredient individually influences and impacts the pH of the batch.
Ingredient
Affect On pH
Kombucha Starter Tea
Decreases
SCOBY
Decreases
Water
No Change
Sugar
No Change
Honey
Decreases
Tea
Decreases

Kombucha Starter Tea
- This tea has come from a previous batch of fermented kombucha tea so the pH will be at that kombucha tea pH level, roughly 2.5 - 4. When added to the new batch of kombucha, it will cause the pH of the batch to lower.
SCOBY - A SCOBY is a large culture packed full of bacteria. As SCOBY is usually stored in a SCOBY hotel or transported in starter tea, it soaks up the kombucha fluid. Just like the starter tea, it will likely lower the pH of the new batch.
Water - Most recipes for new batches recommend using un-chlorinated filtered water. Pure water has a pH of between 6.5 - 8, commonly 7 - otherwise known as neutral. The other ingredients' pH will easily influence a neutral pH. 
Sugar - Sugar is poured in as a solid then dissolves in the tea. Both when as solid or when dissolved in liquid it will not change the pH. So the impact is zero: the pH before adding and after adding will remain the same.
Honey - If you're brewing Jun or other flavors of kombucha you'll need to know honey's pH. On average it will sit between 3.4-6.1. Slightly on the acidic side of the spectrum.
Tea - This will depend on the type of tea you're using to brew your batch. Green tea is relatively high at 7-10, whereas black tea is much lower at 4.9-5.5.

Testing The pH Of Kombucha 

Digital pH Meter vs. Litmus Paper: Considerations When Buying 

There are many methods for measuring pH each with their pros and cons. A breakdown is below for some points to consider before buying a pH tester. 
Accuracy - The number one factor you should consider is the accuracy, for the old universal indicator paper style, the accuracy can be hard to know. They rely heavily on the color of the paper, so if it's between a number or the lighting changes, the correct reading is hard to know. When picking a meter, look for accuracy above all else, has it been tested? Can it measure to 0.1 of a reading? These are some of the questions you should ask.
Price - The reason why litmus paper or other analog styles of testing are still so popular is due to the price being so low. Some companies even offering 100 tests for under $3. A digital version can't compete on price.
Brand - There aren't any household names that produce testers. So as far as brand goes, there isn't much loyalty. If we were recommending a digital reader, we would look for something under $30 that has high ratings online.
Size - Some of the fancy reading kits can be quite large. But we need to remember that it must fit inside the mouth of the jar we're looking to test. When picking think about the size of the device and if it fits in the jar mouth for the most common jars you will use. 

Testing Kombucha pH With An Electronic Reader

A pH tester is 100% necessary when brewing kombucha, an electric reader is probably the simplest and most accurate method of measurement. Often they will have a probe or pointed edge for you to place inside the liquid.
1. Make sure your brew has been stirred (stir very gently just once)
2. Following your device's instructions turn your reader on and make sure it's ready
3. Place the measuring end inside the jar (move the scoby aside if necessary)
4. Press the measure button on your device
5. Read the pH reading
If you're happy with the corresponding pH then you can skip the next section. If not check out the section below which lets you know how to lower the pH of your brew.

 

Testing Kombucha pH With Test Strips

litmus_paper

Do I need pH Strips for kombucha? If you're brewing kombucha using an all-in-one kit often, they'll add litmus paper which will contain roughly 100 strips and colors with the corresponding pH for you to judge. 
1. Make sure your brew has been stirred (stir very gently just once)
2. Remove a piece of litmus paper from the pack

removing_litmus_paper

3. Place a piece of paper inside the jar to reach the brew (you may have to lift or move the SCOBY)

paper_test_in_jar

4. Remove the paper from the jar
5. Be in a light environment and hold up the paper to the light and use the litmus package to determine the pH of your brew

ph_test_results

6. If you're happy with the pH then you can leave the brew. If not check out the section below which lets you know how to lower the pH of your brew.

pH And Brewing Guide

Brewing

Once the ingredients are in the brewing vessel, check the pH.
Make sure that you have lightly stirred the mixture. This is so when you're testing you don't accidentally test one area or one ingredient. Instead, you receive the pH for the whole vessel. 
The test results we're looking for is a pH between 2.5-4.2. This is the "safe range". As some pH testers are inaccurate, we would often recommend taking a couple of tests from different areas of the vessel to be sure.

What to do if my pH is too high?

If the pH of your brew is too high, this needs to be addressed before it starts brewing. A high pH will not create an environment that inhibits bacteria and growth, which could potentially be very dangerous for your health. Here are two ways to lower your brew pH.
Method 1: Adding Vinegar To Your Brew

vinegar_measuring

1. Add 1 tablespoon of white vinegar 
2. Stir slowly to ensure the brew is thoroughly mixed
3. Retest pH to see if it's below the critical 4.2 number and above 2.5
4. Below 4.5 then you're safe to start brewing
5. Higher than 4.5 you should carry on repeating this process of adding vinegar until the pH comes below that level
Method 2: Adding Kombucha Tea To Your Brew
1. Add half a bottle of your favorite kombucha bottle (8oz or 250ml is usually enough)
2. Stir gently, so the batch is mixed
3. Retest pH to see if it's below the critical 4.2 number and above 2.5
4. If it's in this critical range, then you're good to start brewing
5. If it's still too high, add some more kombucha tea and keep repeating until the pH hits that range

Can Kombucha pH Be Too Low?

Yes, absolutely! Although not nearly as common a problem, kombucha's pH can be too low. The commonly quotes figure would be anything below 2.5 is too low. This can be tested using the same methods shown above. 
If the pH is below 2.5, the acidic nature can damage your health. Under no circumstances should you drink anything this acidic. 
To raise the pH you will need to dilute the existing batch. One method is to add more un-chlorinated, filtered water. Another way to not waste the brew would be to use this batch as starter liquid for another batch.

Second Ferment And pH

2nd fermentation and pH isn't as important. It usually sits between a range of 2.5-3.5. A lot of commercial brewers will at this point pasteurize the brew killing any chance of bacterial growth. The main reason pH was so crucial during the brew was to stop the growth of bacteria. So if it's been pasteurized all of the dangerous bacteria will have been killed.
As a homebrewer, I would check the pH to make sure the final batch. Between 2.5-3.5 then you can bottle and get ready for flavoring! 
If you pasteurize your home-brewed kombucha, I would still check but be confident that following a correct pasteurizing process then the bacteria will be killed.

How Often Should You Test The pH When Brewing?

Test the pH after you have made the batch, to make sure it is between 2.5 - 4.2. Then check daily to ensure the environment hasn't changed and that the brew will still be safe to drink when ready. 

pH By Type Of Kombucha Brew

The pH of a brew will directly influence the taste of the finished kombucha. The primary way in which this is experienced is by the level of sweetness in the finished product. As a general rule, the higher the pH is the sweeter the brew.
As a general rule of thumb the longer you leave the kombucha to brew the more acidic it will become, so when you're approaching the end of the brewing time, you'll need to check the pH to be sure it's within the critical range.
So if you're looking for that sweet elixir aim for a slightly higher pH, somewhere towards 3.5, but be sure to keep it still in the safe range.
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