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Kombucha, science, homebrew, booch, how to make kombucha

The Science Behind Kombucha

Kombucha is very fun and very easy to make, but what’s REALLY happening under that creepy looking SCOBY?  This week we we talk about making your own kombucha, adding fruit and flavors, and the science behind what is happening during this ancient fermentation process!

SCOBY Symbiotic Culture of Bacteria and Yeast Acetobacter vinegar acetic acid

What is a SCOBY??

As many of you know, the SCOBY is what really makes kombucha.  Just like brewing, we just make the base and try to make conditions perfect to invite the natural organisms to do their thing.  The SCOBY itself is a very cool, and kind of gross, concept. Basically, a colony made up of tons of different types of probiotics, including saccharomyces, lactobacillus, brettanomyces, gluconacetobacter and acetobacter, that live and work together in harmony ‘grow’ this thing.  They all need a village to live in, so they somehow create this floating skin-like growth that pulls double duty as a place to live and multiply and an oxygen barrier/oxygen flow mediator so that organisms that want to be anaerobic can work and organisms that need oxygen to work can have access to oxygen.  In sour beer terms, it is a pellicle plain and simple.

A good way to look at a SCOBY is to look at it like one of those cool kveik rings, or a mash paddle full of yeast and microorganisms used traditionally in brewing.  It’s an inoculation device, just for tea and simple sugar based fermentations instead of malt based fermentations.

If you think about it, many of the same organisms, lacto especially, are the same as the ones present in making kimchi or sauerkraut.  The process is actually much closer to making vinegar than it is to fermenting probiotic food, however, and vinegar (acetic acid) is one of the primary flavors present in most kombucha.

SCOBY Growth

Another cool thing about SCOBY’s is that they are continually growing.  As your kombucha routine becomes more regular, the microorganisms will continue to build their ‘villages’ one on top of the other in flat layers.  This is why people who make kombucha regularly always have so many SCOBY’s to share! It’s easy enough to peel off a layer or even cut off a piece and start a whole new fermentation from scratch. 

One thing to remember about your SCOBY is that once it’s grown, it will grow to cover the top of your tea, no matter the size of your fermentor.  This means that if you use a 6.5 gallon Bucket fermentor, you will have a frisbee sized SCOBY!

Acetic Acid Molecule

What Role Does pH Play?

As we said before, the bugs we’re working with, and trying to promote, are different strains of probiotics.  When we make the kombucha and add in the ‘starter’ liquid, or liquid from a previous batch or some commercial kombucha, what we’re doing is trying to lower the pH of solution enough to deter any of the bad bacteria, either bacteria that tastes awful or dangerous bacteria, to begin the fermentation process before our SCOBY culture can dig in and outperform any competition.  This is the same as adding salt to your fermented foods to create an environment that is only friendly to the bugs we want!

The important thing to remember is that pH plays a huge role in the making of kombucha, and the health conditions around drinking it.  If you make kombucha that is way too acetic, it’s a lot like drinking vinegar. While a tablespoon a day of apple cider vinegar can help your body regulate pH, a few pints a day can cause your body’s pH to drop drastically, and that’s never a good thing.

According to the CDC, some of the only known deaths ‘could have possibly’ been caused by kombucha drinkers who imbibed too much over a short period.  There are a lot of variables in that statement, as commercial kombucha is well regulated nowadays, and that could have been highly acetic homebrewed kombucha that caused that, but it’s important to measure your kombucha as a regular part of your process!

Commercial booch producers have to have their products between 2.5 and 4.2, which is not a bad range to shoot for.  If you prefer more acidic flavors, you can easily aim towards the lower end, and vice versa. It’s plenty of range to give you control and creativity over your product while staying in the safe realm.  Also, maybe try to stay away from binge drinking your booch! There is such a thing as too much healthy tea!

pH Meter Kombucha Reading

Measuring your pH is an easy process.  While we like to use our Milwaukee pH Meter for accuracy, you can also use Universal pH Test Papers to make sure that you’re in range.  Once your kombucha routine gets moving, and your SCOBY begins to grow a bigger colony, especially if you are doing a gallon at a time, you will be removing and adding booch about every 7 days, despite the process taking closer to 14 for your first few gallons.  This is where your pH testing comes in, because you’ll want to find the safe pH that you like and pull and replenish your kombucha at that point.

Bottled Kombucha Homebrew

Are There Really Health Benefits?

While acetic acid is the primary, driving flavor, one of the reasons kombucha is purported to be such a healthy drink for the digestive tract is the presence of tons of other organic acids, vitamins and compounds produced in part by the various good bacteria involved in the process.  To name a few, these include acetic, gluconic, glucuronic, citric, lactic, malic, tartaric, malonic, oxalic, succinic,and pyruvic acids. It’s also full of complex B vitamins, C vitamins, amino acids, biogenic amines, purines, pigments, lipids, proteins, tea polyphenols, and tons of other organic compounds.

While there has not been a ton of research done, there has been more and more done over the past decade.  Kombucha is generally known as a fantastic probiotic supplement, is sometimes used as a dietary supplement, and it can also be a good, mid-day energy shot for just about anyone due to the B vitamin complex and C vitamin concentration.  One also reaps the benefits of green tea or black tea, and some of the other compounds may give your immune system a boost.

So, the short answer is yes.  Because of the wide array or healthy, organic compounds involved in the whole thing, if you aren’t drinking 4 or 5 of these a day, kombucha can definitely give you a good boost!  The key, as with anything, is moderation.

Fermenting Kombucha

The Actual Process of Making Kombucha

So this booch fermentation is not so different from any other fermentation that you do.  It’s all connected, and it’s pretty easy to control variables like acetic acid and alcohol content with the proper process.

Our basic Hibiscus Rose Kombucha Recipe goes like this:

The whole process goes back to proper extraction of herbs and teas (check out our article about Brewing with Herbs and Spices for a recap!), as well as proper sanitation.  Even though we’re fermenting with bugs and bacteria, WE want to control all of the microorganisms going into the kombucha as much as possible, which means proper sanitization techniques all the way through, including boiling all water used (you’ll need to to get proper extraction from the hibiscus and rosehips anyway, as well as dissolving your sugar into solution), using Star San in your fermentor, and making sure that everything that touches solution post boil is properly sanitized.

One thing I like to control, especially once I get into the weekly routine, is the amount of acid.  I like a very lightly acidic kombucha, right at the top of the pH range. You can control the amount of acid produced by the amount of ethanol in solution, because the acetic acid producing bacteria eat ethanol to produce acetic acid in the same way that the other lactic acid bacteria eat sugar and produce ethanol.  This whole process is very full circle, and also why we leave kombucha open as opposed to closing the fermentation and making it anaerobic. Acetic acid bacteria require oxygen, so that part of the process is aerobic.

Once the culture grows and more and more bacteria are in solution, it’s easy enough to make a slightly less sugary tea base to get a less acidic finished product.  It’s just as easy to add some more sugar to get to the lower end of the pH range and have a bit more acid if you like that little bit of extra bite!

The actual brewing process for the base tea is very simple, and it doesn’t have to be our Hibiscus Rose recipe!  You can make a very nice and versatile base tea recipe with green tea, black tea, and even awesome tea blends, such as our Blackberry Fruit Black Tea Blend.  From here, you can bottle with fruit purees, flavorings, and pretty much make whatever you want!  I love the versatility of base kombucha, as it reminds me of a berliner weisse that you can fruit and flavor infinitely to great effect!

The only things you will want to stay away from are high concentrations of herbal teas, such as rooibos teas or 100% herbal teas.  For some reason, these can have a negative impact on your SCOBY culture, so try to limit these to around 30% of your total tea blend, if possible.

Kombucha Bottled in Flip Tops

Bottling and Carbonating Your Booch

You can carbonate your booch as much or as little as you would like.  The process is the same as for bottling homebrew, which is just adding a little bit more sugar and allowing an extra few days to ferment inside of the bottle to allow natural carbonation to happen.  Flip top bottles are ideal for this, and we like the Clear Flip Tops because they showcase whatever fruit or herbal colors that you’ve added!

When adding fruit and flavor to your bottled product, try adding your fruit as a puree and using that as your carbonation catalyst.  This way, you won’t have to add any extra sugar, and you can use the sugars in the fresh fruit to both back-sweeten and carbonate. Depending on the fruit, start with a few ounces of puree, then add kombucha immediately.  Allow 2 -3 days at normal room temperatures for carbonation, then get your bottles in the fridge and keep them cold so that they don’t over-carbonate. Use the same process with simple sugar, or even easier, Carbonation Drops, if you aren’t adding fruit, or if you’re using Flavorings for your booch.

At the end of the day, kombucha can be a healthy and tasty drink that is fun to ferment!  Store bought kombucha is expensive enough that once you get rolling on making your own, you can have any and every flavor you want, all of the benefits, for literally pennies on the dollar!  We have a Kombucha Starter Kit that makes getting started fun and easy, so give it a shot!

Thank you all for reading!  Check out our video on BrewChatter TV about Making Kombucha at Home!  Don’t forget to connect with us on Facebook, Instagram and Twitter to stay up to date on all of our fun fermentations and happenings!  Comment below about your kombucha, your process, and what kinds of flavors you like to use! Brew On!

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