Kombucha Brewing FAQ
What is a SCOBY ?
SCOBY stands for Symbiotic Colony Of Bacteria and Yeast. It’s a cooperative of microorganisms that feed on tea and sugar, and whose products of metabolism make up kombucha.
What type of container should I use to grow my SCOBY?
In brewing your own home-made kombucha, there are a few characteristics of your brewing vessel that you should look for.
- The vessel should be glass or ceramic. While many will say that food-grade plastic can be used, undesirable flavors often result from continued use of plastic. Glass provides an inactive surface for fermentation to proceed, and will not allow the leaching of chemicals into your brew. If brewing with ceramic, be sure it is lead-free (the crocks we carry are lead-free and made in the USA).
- The vessel should be wide-mouthed. The kombucha SCOBY requires that air be constantly exchanged with the outside environment, as it is constantly taking in oxygen and expelling CO2. A wide surface area ensures fast growth, as well as quick acidification of the tea. This results in a healthy culture. The wider the area for the culture to exchange gases, the more numerous are the antibacterial byproducts of SCOBY metabolism. Keep in mind that although your SCOBY will grow in tall, narrow-mouthed vessels, it will do so less vigorously.
- The size of the vessel is important, though not quite so much as the available surface area. Similar to the surface area, however, the more shallow the depth of liquid in the fermentation vessel, the faster the SCOBY grows and processes the tea into delicious kombucha.
- The shape of the vessel is a matter of personal preference, and the culture will take the shape of the container at the level of the liquid’s surface.
How can I store SCOBYs for later use?
While it is easy to “store” a SCOBY at room temperature, it requires somewhat regular maintenance, in the form of adding more tea and sugar (even a small amount) to keep it from drying out and dying from malnutrition. At room temperature, it will process the nutrients in the starter much, much more quickly than it will in the fridge. As such, a SCOBY is best stored in the refrigerator. Keep it submerged in kombucha in a covered container where it will go into a dormant state and will be viable for quite a long time. A glass or ceramic container is recommended, but plastic will work just fine, especially since it's not really undergoing extensive metabolic processes, to any great extent, while inside your refrigerator. Many shy away from using plastic to store or brew any kombucha ingredients, just to be sure no unwanted flavors or or chemicals are passed on to the tea or SCOBY.
What kind of tea is best to use in making kombucha?
An important note before we start: the tea used in kombucha fermentation is as much for the 'buch drinker as it is for the SCOBY. Tea and sugar are the necessary metabolic foods that the culture needs to grow and thrive. The tea and sweetener you use is also, of course, an important factor in the final flavor of your kombucha.
Black Oolong Green White Pu-Erh
- Black tea is high in nitrogen and tannins giving your SCOBY a strong, nutrient-dense frame to work within, they will give you deep woodsy, honey sweet, nutty flavors.
- Oolong Tea produces a robust SCOBY. Smells range from fruit, honey, wood and roasted aromas to green mountainside gardens.
- Green tea makes both a wonderful, mineral-rich final brew and a great addition when combined with others in a brew blend SCOBYs are thinner but healthy.
- White Tea is simple, and delicate. It is one of the most innocuous but alluring teas, and they often astound those unfamiliar with the style.
- Pu-Erh Tea produces a giant and healthy SCOBY. Smells of sweet notes of earth, tree bark and mushrooms - complex, highly medicinal and refreshing kombuchas are made with pu-erhs.
Things to consider
Oil content of teas
Teas that are flavored, or that have high volatile oil content should *ideally be avoided when brewing kombucha. Oil inhibits the SCOBY’s ability to form a semi-permeable membrane on top of the tea, and while your culture may process your strawberry leaf, or blackberry leaf tea into a tasty beverage, such a constitution is simply not enough to maintain the virility of the culture for an extended period of time, as is black tea. You are encouraged to experiment with your own mixtures, but adding a portion of black or green tea to your brew is a good idea to maintain the health of your SCOBY.
Sugar - Can I use honey as my sugar ingredient instead of white or cane sugar?
When introducing new ingredients to your kombucha it is best to do in small increments and build up. Take maple syrup, for example. Start with mostly pure cane sugar and a bit of maple syrup, and increase the maple syrup with each batch, at a rate at which the SCOBY seems to be reacting best. Think of it as "training" your SCOBY to survive on maple syrup and tea as opposed to sugar and tea. You may find some obstacles along the way, so to be safe you may also want to have a regular sugar brew going in another jar to keep a definite healthy culture.
Kombucha Brooklyn propagates honey-specific cultures that make superb kombucha called jun. Check them out here.
Related blog entries:
Sanitation - I’ve read in some places that it’s not necessary to sanitize kombucha brewing equipment, how far should I go in my kombucha sanitization?
Sanitation is not necessary, but we HIGHLY recommend that you keep a bottle of over-fermented ‘buch vinegar close to your workspace. Rinse your brew vessel with this before you add your nutrient and SCOBY. A cup of ‘buch vinegar sloshed around in there and then poured out will ward off any microbial intruders and prep the environment. Kombuchatize it! Another option is using a brewing sanitizer.
The acidity of your brew (which is contributed to by adding starter liquid) as well as making sure the temperature is warm, adding plenty of nutritive tea/sugar mix to your culture, and keeping the top of your brew jar covered are all things to be sure of when you are brewing kombucha. A healthy kombucha culture will naturally fend off or accept air-borne yeasts, should they make their way to the culture. As such, a brew started on the East Coast of the US will be different from one on the West Coast, based on the ambiance of the surrounding environment. The main thing is to maintain a healthy culture, and be sure to watch for mold (though it is rare) on top of your culture. In our experience, we've very rarely seen a batch of kombucha go bad (and never our own) - but always have we actively cleaned with dish soap and hot water, and used either white vinegar or kombucha to rinse all of our instruments before getting to the nitty-gritty of handling a SCOBY, transferring kombucha, between vessels, etc. Before bottling, we always let bottles soak in very hot soapy dish water and use a bottle-brush to get rid of any remaining deposits from previous brews. So, to answer your question, it's up to you as a home-brewer. As kombucha is usually consumed only after an initial ferment, and drinks like wine and beer undergo a secondary fermentation, I would say there is less of a chance of contaminating a batch of kombucha than there is in having your alcoholic beverage go bad, simply due to the time the brew is undergoing fermentation.
Bottling your Brew
Read a blog entry about bottling and attaining carbonation in your home brew here!
Troubleshooting and Brewing Problems
Of the ferments that one can make at home, kombucha is one of the easiest to keep safe and healthy. Much of the health of your brew is predetermined by liquid 'buch starter. When added to the nute in the proper amount, liquid 'buch starter will immediately lower the pH. This gives your fledgling batch of 'buch an instant competitive advantage over unwanted microbial contaminants like mold.
When a problem does arise, however, it is good to know what you are looking at. The most common foreign invaders are mold and fruit flies. If either of these happen, toss your entire brew, SCOBY and all, and start over from scratch. These guys will weaken and eventually destroy your brew, not to mention that they may change the flavor and just flat-out make your not want to drink the stuff. It is important to recognize that it is difficult to make kombucha in a way that will actually make you sick. Read on and learn more about kombucha's competitors.
Yeast Vs. Mold
Yeast Strands and blobs: Along with the new SCOBY, you may start to see brown strands forming in the brew. They might hang from the SCOBY or float freely in the nute. These strands are yeast colonies that like to stick together in long chains. Don't fret; they aren't some weird unwanted party crashers. They are part of the brew and offer you nothing but kombucha goodness. If you want to minimize these strands in future brews, filter them out of your liquid 'buch starter before you inoculate your brew. This will limit their growth. Sometimes the yeast will also attach itself to the top of the SCOBY, form blobs, and even dry on the surface, giving the culture dark brown spots or areas that many new brewers easily confuse with mold.
Yeast Yeast Yeast Yeast
Mold: The most common contamination is mold. Molds are resilient microscopic fungi that can grow on almost any type of nutrient-dense material. We've all let a loaf of bread go a little too long and had greenish, bluish, whitish, fuzzy, soft mold grow on it. It's generally not dangerous unless you have an allergy to mold. Some people just cut it off and carry on with the sandwich making.
Mold Mold Mold Mold
Just like bread, when your 'buch gets infiltrated and overtaken by mold, you will know it. A patch of either green, blue, white, or black fuzzy stuff will be growing on top of your new SCOBY or on the surface of the liquid. Many first time brewers will mistake a yeast swell or new SCOBY formation as mold. The way to overcome these freshmen blues is to look at it like a taxonomist. Mold always needs air, so it will always form on the surface of the SCOBY or liquid. It will never form underneath the surface of the liquid. It will either be dry and fuzzy on the surface or look like a separate distict entity growing in splotches that don't really meld together. Compare yours with the images and pay special attention to the points just mentioned. At the end of the day, if you are still unsure, email a picture to us at email@example.com! We are always happy to help.
If you confirm that you do have mold, don't futz around. Toss the entire batch and start again. If you have other brews next to a mold swarm, it can easily spread through airborne mold spores, so go ahead and toss those too. Mold contamination is usually caused by culture death from adding the culture to liquid that is too hot, under acidification when you set up your brew, or fermentation temperatures that are below optimal brewing range.
To Beat Mold:
- Always verify that your nute is below 90F before adding the SCOBY or liquid 'buch starter.
- Always keep your fermentation temperature in the right range.
- Always add the correct amount of starter to your nute.
- Avoid letting any particulate from your tea into the fermentation vessel.
Foreign Invaders: Unwanted Kompany
Fruit Flies (Drosophila melanogaster). These little devils come out of nowhere. Sometimes it feels like they appear out of thin air. They are little warriors that somehow find their way into your brew with even the most careful precautions. Fruit flies like to make a nice home for themselves and their burgeoning families on your SCOBY.
Once there, they will immediately get frisky and start multiplying, making little baby flies, aka larvae, that will creep and crawl all over the surface of your brew. Those little baby devils will eventually hatch and become flies themselves, trapped under your fermentation vessel cover. If left unattended, one fruit fly will create an empire of brothers and sisters claiming your home brew as their own.
If you get an infestation of fruit flies, toss the entire batch and start again. You may be a 'buch brigadier, but dude, you are no match for an army of fruit flies.
Fruit fly traps are easy to make, and might just be the difference between tasty brew or no brew. An empty small-mouth bottle with a paper funnel stuck in it and a splash of kombucha at the bottom will attract flies into entrapment and imminent doom. In the summer months we catch thousands that way.
Vinegar eel nematodes (Turbatrixaceti). Vinegar eels are an interesting breed. Commonly found in vinegar manufacturing facilities, they feed off of the microbes that proliferate in both vinegar and kombucha. Although uncommon in the home brew setup, if you do get them, vinegar eels are difficult to detect. A brew of 'buch can house vinegar eels for months, and only the trained eye during careful review will notice them. They are passed down batch to batch, and it takes a while for the effects to become apparent. The good news is that the FDA has determined they are harmless and nonparasitic. The bad news is that over time vinegar eels will slowly kill your culture. If your kombucha is not developing as quickly as it normally does, if the flavor profile changes unexpectedly, or if your SCOBY starts to deteriorate and you find it lacks structure, check for vinegar eels.
Find them by taking your brew into a dark room and shining a flashlight into the ferm vessel. If it's clear glass, you can shine your light into the side. If you are in ceramic, shine your light into the top after pushing the SCOBY way down. If you've got eels, they will swim and wiggle their way toward the light. If vinegar eels are discovered, toss all contaminated brews and start fresh with new SCOBYs and liquid 'buch starter from noncontaminated sources. Don't mess around when you are cleaning up after vinegar eel infestation. It is remarkable how resilient they are. Use boiling water to sterilize everything that has come in contact with contaminated brew before starting a fresh batch.
It is always best to restart with a fully formed SCOBY, but if you are desperate, a successful batch of kombucha can be started with just a bottle of kombucha and your nute. All the microorganisms and yummy goodness that is needed to start a new kombucha SCOBY is in the kombucha itself. If you start a new brew from just a bottle of kombucha alone, your brew will take an additional one to two weeks to fully ferment. The first SCOBY may not be the most robust SCOBY in the world. In time your culture will adapt and gain strength. A few batches down the line and you will have a nice culture going, SCOBY and all. Ferment in the upper region of the temperature, around 80F, if using only liquid 'buch starter.
Please email us a photo at firstname.lastname@example.org before throwing your kombucha away! It may only be yeast. If your photo is a great example, we may use it here unless otherwise notified.