Guide to kombucha pH
Long story short:
A common misconception about pH is that it can tell you
when your kombucha is “done” fermenting and ready to
bottle. This is not the case. pH is not an indicator of
doneness, and it’s not a measure of sweetness.
The best way to test if your kombucha is done is to taste it.
pH is a good indicator that your brew is fermenting and
acidifying properly but there’s no “right” pH to bottle at.
Oftentimes my pH will drop most significantly the first few
days after I brew. But it’ll still be way too sweet for my taste.
So I let it ferment longer.
And kombucha at a certain pH won’t always taste the same. For example, I’ve had a couple batches at 3.2 pH but they didn’t taste the same because one was fermenting a bit longer than the other and therefore less sweet.
pH is good for troubleshooting or making sure your brew is fermenting and acidifying properly, but the best way to tell if it’s done is to just taste it.
So tell me more about pH...
pH is simply a measure of acidity. It won’t be able to tell you when your brew is ready to drink or bottle. Like I mentioned, your tongue is the best tool for that (you can also read more about that here).
Oftentimes, kombucha pH drops most significantly in the few days right after you first start your batch. Once it's below 4, it’ll technically be acidic enough to be considered fairly safe from developing mold or harmful pathogens, but it’ll still probably taste too sweet to bottle. You’ll want to continue fermenting it until it tastes right.
It’ll likely keep dropping a bit (the drops are usually more incremental or more slight as it progresses), but ultimately, you’ll have to rely on your unique taste buds and taste preferences to decide when you want to bottle your kombucha.
So what is pH useful for? Why do people even bother with it?
pH is a helpful tool during the beginning stages of first fermentation to help make sure the process is going well and to ensure that your brew is becoming more acidic. A key part of kombucha-making is acidifying sweet tea by adding starter tea from a previously brewed batch of kombucha. That starter tea gets the acidification process going, thereby lowering the brew’s pH. An acidic pH prevents mold growth and harmful pathogens from infecting the brew.
Your brew’s pH should drop below 4 in the first few days of fermentation. That's a sign that the process is “working.”
So, long story short, it can be a good tool to help confirm that your brew is fermenting properly during F1. Lots of commercial kombucha brewing companies use pH as a tool to do exactly that, to make sure their brew is fermenting safely.
Finished kombucha typically falls within a range of 2.5 - 3.5. But those are just estimates. Your own brew may be different, but it shouldn’t be drastically far from that range.
Should I use a pH meter or test strips?
It’s up to you. If you’re curious, by all means do it! I did! I bought a really affordable meter* and some test strips. It was a lot of fun to get another dimension of understanding in my brew cycle.
But honestly, in my day-to-day brewing, I never use my pH meter anymore. The new SCOBY growth at around day 3-4 is really the only indicator I need to know that my kombucha is fermenting just fine. But it can definitely be a helpful tool if you want to be super sure your fermentation is progressing well or if you're having trouble with your brew and want to troubleshoot.
In case you’re curious about my findings when I tested my brews’ pH:
I consistently found that my brews had a starting pH of around 3.9 - 4.2 immediately after I added my starter tea.
The next day or couple days later, it usually drops to around 3.6 - 3.8.
Around 7 - 12 days later, my finished pH is usually around 3.2 - 3.4.
Ultimately, I found that it wasn’t really necessary for me to obsess about my brews’ pH. Testing pH also requires agitating your brew vessels during the early stages of first fermentation (which is something I try to avoid so I don’t hinder scoby growth).
Tips for pH test strips and meters
pH test strips:
These are simple because you just dunk it into your liquid, and it’ll change color. You read a little chart to see what pH that color indicates. I find that these are a little less precise and take some color interpretation when compared to the meter. But they work well enough for kombucha purposes!
Make sure you get ones on the lower end of the pH spectrum. Test strips commonly used for winemaking work just fine since those usually measure between 2.8 - 4.4.
These can vary greatly in price, but I don’t think it’s worth it to shell out for a super expensive one. I got this one.
You'll want to have at least one type of buffer solution to make sure your meter is accurate. Buffer solution is liquid that’s at a set pH. You can use it to test your meter and calibrate it (a.k.a fix it) if your meter is inaccurate.
For example, if you have a buffer solution that’s 4.01 and you dunk your meter in it, but the meter says 4.05, you’ll need to use a little screwdriver (most pH meters come with one) to dial back your meter and correct it so that it reads 4.01.
Once it's calibrated and accurate, remember to rinse it well with water before sticking it in your kombucha! People recommend distilled for rinsing pH meters, but I hardly ever have distilled water on hand anymore, so I just use filtered water.
Should you refrigerate SCOBYs?
*On this page, you’ll find some affiliate links to sources where I’ve purchased my ingredients/materials that I use. I may get a small cut of Amazon's profit for finding + recommending them to you. It won't cost you any more than you’d normally pay for them. I went through a lot of trial and error to find low-cost, high-quality options to save us all money. But feel free to purchase from wherever you like!