Why Is PH Important for Brewing Kombucha?
Unlocking the Secret of Perfect Kombucha: The Importance of Monitoring pH Levels
Kombucha pH
Before we go over kombucha pH levels, lets briefly go over pH. pH is a measurement of hydrogen ions within a substance, which translates to its level of acidity. The scale ranges from 0, being the most acidic, to 14, the most alkaline. Water is considered neutral at a pH of 7, noting that tap water pH levels can vary as it is not pure water.
pH Level of Kombucha
Kombucha pH level is very important when brewing; while simple, there are easy rules to follow to know that your kombucha’s pH level is where it needs to be. The starting pH of kombucha needs to be at or under 4.5. As your kombucha ferments, the pH will drop while the different bacteria create acetic and gluconic acid and lower the pH. Finished kombucha is based on taste, with a pH range between 2.5 and 3.5. So if you like it sweet, the pH will tend to be higher, towards 3.5 pH. If you like your kombucha tart, you should let it ferment longer while tasting daily until you are happy with the tartness of your brew. Longer fermentation will have a lower pH but keep it above 2.5 pH.
So how do we test kombucha pH levels?
The two ways to take a pH reading are either with kombucha pH test strips or a digital pH meter.
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pH Test Strips
To take a pH reading with test strips you simply wet the end of the pH test paper. Once wet, the pH paper will change colors so now you just need to compare the color of the strip to the color chart indicator provided (pictured above). The closest color match will be the current pH reading.
Digital pH Meter
Taking a pH reading with a pH meter is easy. You simply turn it on and insert the pH test probe in the liquid solution being tested. The meter’s LCD will display the pH value on the side of the meter. pH meters are extremely helpful but it’s important to note that all digital pH meters need to be periodically calibrated. Calibration (pictured above) starts with adding a pH powder packet to a glass of distilled water. Each meter is a little different here but you will ultimately hit an autocalibration button on the meter and submerged the testing probe. The meter will eventually flash when the autocalibration is complete and you are now ready to use your meter.
Testing kombucha pH level
Testing your kombucha a few times during your brew is a good idea to understand the safety and progress of your brew.
The first pH reading is taken when you start your batch. When brewing kombucha, you brew sweet tea and then add your kombucha SCOBY. Once your starter culture is added, this is when you take your first pH reading to ensure your starting pH level is at or below 4.5. Remove a liquid sample from your batch to wet your pH strip and compare the strip to the color chart provided with your strips. If your pH reading is higher than 4.5, you will need to add more starter tea to your batch until it is under this threshold.
Your next pH reading should be taken about day 7 alongside a taste test. You can start to develop a taste for what pH you prefer this way. Kombucha can take anywhere between 7 to 21 days to ferment, depending on temperature. So at day 7, you can begin tasting your brew, if it’s too sweet cover and allow to ferment longer. Continue tasting daily until this balance is achieved – up to 21 days. Once the desired balance is reached, take a final pH reading. This will give you an idea of your preferred kombucha pH range and let you know what pH to aim for during your next brew.
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How do you check the PH in the tea?
Hi Rene!
You can check the pH either with pH strips or a pH meter, both of which work great. pH meters do have to be calibrated regularly, so I would suggest purchasing pH strips for ease of use.
Ruthie
I recently purchased a Jun scoby on Amazon. It arrived Thursday. I had purchased a new jar to brew my tea. After washing the jar I added my honey and green tea mixture. When cooled to room temp I added my scoby and starter. A new scoby was beginning to develop but on day three my scoby sank to the bottom of the jar. Is there anything I can do? Is my scoby still viable?
Hi Shannon!
It’s totally okay that your SCOBY fell :) In time, a new SCOBY will just form on the surface and all will be well! Even if your SCOBY hasn’t fully re-formed within the normal fermenting time frame (7ish days) go ahead and taste it and see what you think! If it tastes tart and just a little sweet then bottle it up! If it tastes really sweet, let it be for a few more days. Cheers!
Hi, When I tested the pH of the sweet tea with the starter culture pouch it was 4.0, so since it wasn’t 4.5 I followed the directions and added 1 TBSP of vinegar. That took it down closer to 3.5. Should I have added something else to bring the pH up to 4.5?
Hi Terri!
The starting pH just needs to be below 4.5. Anything under 4.5 will protect your brew from contaminants such as mold. Since your pH tested at a 4, that is below the 4.5 threshold so you were safe to let it go :). Adding vinegar to the brew cannot hurt though, only protect it further so definitely no harm done.
Hope this helps! If you need more clarification, email me ruthie@fermentaholics.com :)
When I use a test strip to measure the PH, whether on the first or second fermentation, (generally between 14 to 20 days into the first fermentation,)I always seem to get a reading of 3.5, There always seems to be a tiny of green in the Yellow color, giving it a 3.5,reading. I wanted to get to 2.5 to get a slightly more tart and or carbonated taste. Is there something I should do ( other than more time) to get a lower reading? Is there a difference between quality of pH strips? Thx!
Hi Sue,
As you mentioned in time, the pH lowers. To move things along, make sure your brew is kept in the proper temperature range between 75-85 F. You can also try using more starter tea with each brew. Last, airflow is good, a gallon jar provides enough, but you can also try increasing the surface space of your brew vessel. For pH strips, most are in a broad range with increments of .5, which work great. If you wanted to drill down further, you could buy a digital meter that reads in .1 increments. Last, carbonation is created in the second fermentation; you will never have carbonated kombucha after the first or primary fermentation.
For more on this see our post on How to Carbonate Kombucha
Hi, will to low of PH kill the Scooby or slow the fermentation process? My 2nd batch on day 7 was at 3.0.
As long as it is within the ranges of about 2.5-4, your scoby will be just fine :) Have you tasted it at that pH?
tastes is great, carbonation is problematic. General question about scoby growth, it seems to be grow very slow (even at a continuous 78-79 degrees). after two batchs the combined two new scabies are not as think as the one we purchased from you. wondering how we grow a nice think one like yours?
Hi David!
It will happen with time. What brewing ratios are you working with (sugar/tea/water)?
As I relate some of the science of Kobmucha brewing to my home brewing efforts to make kettle soured beers, I lower my ph (lactic acid) to 4.5 when I pitch Lactobacillus Plantarum to start the souring process. The lowered ph provides a hostile environment for unwanted “nasties” to ruin the beer.
My question is: If I don’t have any starter tea (just a small scoby) to bring down the ph, can I use lactic acid and bring down to 4.5? I have a ph meter so I can make this adjustment accurately. Many thanks!
Hi Morrey! Adding lactic acid will certainly alter the natural flavors of the kombucha, making it more tart. It can’t hurt to experiment if you like it tart, but that will be a side effect, as you know from kettle souring your brews.
If you are going to add anything to bring the pH down without altering the flavor, you can use distilled white vinegar. (avoid apple cider vinegar which can have vinegar eels)
What I would personally do is brew 2 cups of sweet tea (weakened to match kombucha strength 1 tea bag, 2 tbsp sugar) and once it is cool, put your SCOBY in that for about a week. This will provide you with enough starter tea to get a gallon going. Be sure to monitor the pH of the brew and if it isn’t low enough, go ahead and add some distilled white vinegar to be safe.
If I started my first batch of kombucha at PH 3.1 (by mistake I add in one tablespoon of distilled vinegar) will it be too sour for the outcome result? Is there anything I can do to remedy this situation? What is the ideal PH index for final product?
Hi,
Quick question: my PH seems to have risen during F2 from 2.3 (… end of F1) to now 3.5 after 7 days …. this seems counterintuitive – is this a known problem?
Hi Grant and thanks for reaching out. That is not a problem, as long as the pH is below 4.5 there are no safety concerns. Depending on what you add during secondary fermentation, the pH level can be lowered or raised. Hope this helps and Happy Fermenting!
I used 2 cups of prior batch (PH 2.5) added to my new brew and the PH only dropped to 5.5. The current batch was about 3 liters, including the 2 cups from prior batch. Can I let the PH drop naturally, I already started the 2nd ferment on the rest of the prior batch.
Hi there and thanks for reaching out! Your starting pH is unusually high for the starter you added. Our cultures have a pH of below 3 and they easily bring the pH of a full gallon down to a pH of below 4.5, which is a safety requirement when brewing Kombucha. I would recommend adding more starter and you could always add distilled white vinegar as a last resort – make sure to never add any live kinds of vinegar as they have their own microbial population. Hope this helps and let us know if we can be of further assistance!
I started a second batch using maple syrup for the first time. The pH did not lower at all during 1f (13 days) and remained 3.0. The flavor however, did change favorably and it is amazing. Is it ok if pH did not lower?
Hi there and thanks for reaching out! That is totally ok the pH did not lower considering you started at 3 as opposed to a typical starting pH of 4 to 4.5. Let us know if you have any other questions!