Q&A: When is my kombucha done fermenting? (Updated 5-31-2010)

Q: How do you know when your kombucha is ready to drink, ready to bottle, or if it's done fermenting?

A: If you are brewing using the traditional method, your kombucha may be done at anywhere between 6-14 days. The time may even be more or less, depending on personal preference, the amount and strength of the starter tea you used, and various environmental factors, such as temperature. So how do you know when your kombucha is done? Here is a list of several signs that help to indicate when your kombucha is ready (please note that not all of these need to apply!):

• According to taste- the most important indicator, as individuals have varying preferences for the amount of fizz, the strength of the sweetness, and the intensity of the vinegar-taste of kombucha
• Hard apple cider or apple cider vinegar aroma or taste present
• The kombucha tastes slightly sour or acidic (like vinegar)
• Kombucha gets more cloudy/opaue, and thus becomes lighter in color, the longer it ferments due to yeast reproduction
• The partial/complete formation of a new kombucha baby
• Kombucha is bottled "optimally" at a pH of 2.5 - 3.5 (testing pH is optional)

Note the clearness of the kombucha at the beginning of fermentation (left) and the cloudiness of the kombucha at the end of the primary fermentation process (right). (My apologies if it is hard to tell in this photo).

Note:

• Home-brewed kombucha tastes a lot different than GT's traditional kombucha. I've found that Katalyst and High Country kombucha taste more similar to home-brews.

Kombucha + Fizz (Updated May 27, 2010)

Yes, kombucha can be fizzy.

I've been receiving numerous questions about fizz, so here is what I understand thus far on the matter!

To begin, fizz does not indicate the health of your SCOBY or your ferment. Fizz is more a matter of personal preference, and may indicate the balance of yeasts and bacteria in your brew (1, 2).

For the scientific side on the matter, here are the chemical reactions that occur during kombucha fermentation (3, p. 40):

The yeasts convert sugar to alcohol + carbon dioxide.

C6H1206 -> 2C2H5OH + 2CO2
sugar -> alcohol + carbon dioxide

The bacteria convert the alcohol to organic acids, such as acetic acid, and water.

C2H5OH + O2 -> CH3COOH + H20
alcohol + oxygen -> acetic acid + water

The CO2 (a gas) that forms reacts with the water in the tea to produce carbonic acid (think of carbonic acid as dissolved CO2). Carbonic acid is a weak acid that readily decomposes back into water and carbon dioxide. When the carbon dioxide bubbles out of the water, you get fizz (4).

CO2 + H2O -> H2CO3
carbon dioxide + water -> carbonic acid

Carbonation and the primary fermentation:
As the new kombucha mushroom forms at the surface during fermentation, the ability for the carbon dioxide to escape decreases, helping to create some of kombucha's natural fizz. The more quickly and the more thick your mushroom forms, the less the CO2 will be able to escape, which can increase the carbonation of your drink (3, p. 33, and 5).

A lower fizz may indicate a lower ratio of yeast to bacteria in your culture. The ratio of yeasts in your brew may be increased by (1):

• Using the bottom SCOBY from your previous batch
• Using more of the kombucha at the bottom of your brew, which tends to be more cloudy/yeasty, for your starter tea.

Carbonation and the second fermentation:

• Fizz can be significantly increased by bottling. My posts related to bottling can be found here.
  
• Consider experimenting with leaving and not leaving airspace. Read my post Bottling and Headroom.
  
• Adding flavors (such as jams, citrus peels, ginger, etc.) during the bottling process can also help to create more fizz. (Similar to adding a primer in beer making).
  
• Beer bottles, which have a very tight seal, are ideal for creating fizz in kombucha. In my experience, when I've used resealable bottles (such as GT's or Katalyst kombucha bottles), I've lost more fizz.
• -The longer you leave your bottles out for a secondary fermentation, the more carbonation will build up. HOWEVER, if you leave your bottles out for too long, you run the risk of them exploding! Some people recommend 1-2 days for a secondary fermentation, others 3-4 days, and some recommend even longer. It all depends on various factors, including the sugar content of your kombucha and the temperature (higher temperatures = faster fermentation).
  -My advice: If you're fermenting a batch, try a bottle after 1 or 2 days (more or less days depending on previous experiences, etc.). Then decide whether your other bottles are ready to refrigerate, or if they could use some more time fermenting.

Some more reading:

• Kombucha Balance on No fizz, Too much fizz, Increasing the ratio of yeasts, and Increasing carbonation
  
• getkombucha: The Fizz Factor #1
• A great thread that discusses fizziness and beverages
  
• Although there is limited information on kombucha and fizz, there is extensive information about carbonation and beer making on the web. Although beer and kombucha are clearly different drinks, they are similar in that they are both fermented beverages. Perhaps looking up beer carbonation will provide more clues as to factors that affect kombucha fizz? Try here and here for starters.

Happy brewing!

Sources:
1. http://users.bestweb.net/~om/kombucha_balance
2. http://www.getkombucha.com/spreisfifa1.html
3. Frank, Gunther W. Kombucha - Healthy beverage and natural remedy from the Far East. 4th ed. Austria: Wilhelm Ennsthaler, 1994.
4. http://uk.answers.yahoo.com/question/index?qid=1006051206579
5. http://kombuchakamp.blogspot.com/2009/04/fizzy-brew.html

Kombucha Bottling 101 (Updated May 27, 2010)

What to do when you are done brewing your kombucha? One thing you can do is bottle your brew.

Why bottle?


Bottling, or a secondary fermentation, allows the yeast to feed on more of the sugar in your kombucha tea. This creates CO2, decreases the amount of sugar in your kombucha, and also makes your drink more carbonated and fizzy, which many people enjoy.

Here are some things to think about when choosing your bottle:
Good:

1. Glass bottles with narrow necks are the most common way to store fermented beverages.
   -old beer bottles* (their tight seals are ideal to create more fizz)
   -EZ Cap (Flip-Top) Beer Bottles
   -wine bottles (nice as a gift or if you're sharing!)
   -etc.

It's your choice:

1. Old kombucha bottles-Pro:
   -GT's now sells kombucha with plastic caps! Many kombucha brands now sell kombucha in reusable bottles.-Con:-In my experience, they sometimes leak, and air can escape more easily as opposed to beer bottles (air leakage can lead to decreased fizz).-If they came with metal caps (ex. the GT ones), the caps usually oxidize/rust easily
   
   
   GT's old metal caps


2. Old plastic bottles
   
   -Pros:
   -The plastic material allows for expansion (decreasing the chance of your bottle exploding).
   -The plastic bottles become hard after a couple of days, signaling that the yeast have consumed most of the sugars in the kombucha and that you are ready to refrigerate it.
   -Cons:
   -Plastics aren't good for the environment.
   -Re-using old plastic bottles could expose you to chemicals. (Especially because Kombucha Tea is acidic!)
   -Note:
   -Some people choose to do an initial secondary ferementation in plastic bottles and then transfer the kombucha into glass bottles for long-term storage. More information on this in the Two Stage Bottling Technique at Kombucha Balance.
   -My recommendation:
   -I don't use plastic bottles for my kombucha, but if you do, please re-use a plastic bottle only once!

DIRECTIONS

1. Optional: Add some flavors to your brew! Put in little pieces of cut up fruit, raisins, goji berries, etc. to your bottle, to add some zing and health benefits to your kombucha! They will provide some more sugars for the yeast to feed on, adding flavors and creating an additional fermentation. It's generally recommended not to add too much biological matter. And the smaller the pieces are, the more surface area that the yeast can act on.What also works well:
   -Citrus fruit peels (ex. grapefruit, lemon, lime, orange)
   -Fresh ginger
   -Jams/jellies/preserves
   Tip:
-If you are using raisins or dried fruit to flavor your kombucha, cut them up first!


2. Fill your bottle(s).-It is up to you on whether or not you would like to leave headroom. For more info, read my post Bottling and Headroom.


3. Cap your bottle(s).
   


4. Leave your bottle(s) out at room temperature for 1-2 days, 4-5 days, or longer.-Personally, I've been doing 4 days, but the time will vary depending on the brew/brewing conditions (ex. the temperature of the room).
   -*PLEASE* do not leave your bottles out for too long. Otherwise, too much CO2 may build up in your bottle, causing it to explode!


5. Refrigerate your kombucha!-If you bottled your kombucha in plastic bottles, the bottles should feel hard when it's ready to refrigerate them.
   -Refrigerating your kombucha will cause the yeast and bacteria to go dormant. Fermentation isn't completely stopped, but is slowed significantly.


6. Enjoy and drink your kombucha! Some people recommend dating your batches, but I always finish drinking my kombucha before the next batch comes around! :)

Note: Like soda, once opened, kombucha goes flat.

*A few comments about beer bottles*:

-If you drink beer, this is a great way to use up old bottles!
-They are easy to get for free. You can even get used ones for free (or cheaply) from restaurants, bars, etc.
-If you feel uncomfortable using old ones, you can buy new beer bottles at your local brewing store, although this is the more expensive route.
-Note- clean them well first!!! Go to your local homebrewing store and get a brush to scrub them out a bit. Then boil them, put them in the dishwasher, use Iodophor, or do whatever it is that will ensure removal of any hiding bacteria/places where bacteria can grow!-To cap your bottles, buying bottle caps are relatively cheap. I got a half pound of caps for only around $3-4 at the Modern Homebrew Emporium in Cambridge. And at only $14, the Red Baron Beer Bottle Capper is a good investment. Find it at your local brewing store or online.
-The one downside- I have to admit that going through bottle caps is not the best for the environment. If this is a concern for you, the EZ Cap (Flip-Top) beer bottles, which are refillable, may be the way to go.

Q&A: How do you grow a thick kombucha mushroom?

Q: How do you grow a thick kombucha mushroom?

A: Remember that Kombucha Mushrooms Come in All Shapes, Sizes, and Colors! Even if your kombucha mother does not look like a perfectly even 1/8 - 1/2 inch thick cream-colored pancake, it could still ferment your kombucha very well!

If you want a thick kombucha mother, you can put some kombucha in a clean glass jar, cover it well with a breathable cloth, and let it sit for a few weeks until a thick mother grows and develops. Or, you can just let one of your kombucha brews ferment for a prolonged period of time until a thick SCOBY forms.

The kombucha will become pretty strong, sour, and acidic if it has been fermenting for a long time, and using this kombucha as starter tea will favor the bacteria and thick SCOBY formation (1). For other uses of sour kombucha, check out Happy Herbalist's recommendations: Kombucha Tea Too Sour?

Acetobacter xylinum has been indicated to be one of the main bacteria in the colony that helps to form the cellulose structure of the kombucha mushroom (2-3). So to favor a thick kombucha mother, you want to favor the bacteria.

For more information on decreasing yeast to bacteria ratios, which will favor the bacteria and a thick SCOBY, visit Kombucha Balance: Decreasing the Ratio of Yeast to Acetobacter Populations.

References:
1. Kombucha Balance: Decreasing the Ratio of Yeast to Acetobacter Populations2. Greenwalt, C.J., R.A. Ledford, and K.H. Steinkraus. "Determination and characterization of the anti-microbial activity of the fermented tea Kombucha." Lebensmittel-Wissenschaft und-Technologie 31 (3) (1998): 291-296.3. Malbasa, R., E. Loncar, and M. Djuric. "Comparison of the products of Kombucha fermentation on sucrose and molasses." Food Chemistry. 106 (2008): 1039-1045.

Brew Your Own Kombucha Workshop at the Boston Skillshare

Join Kombucha Fuel at the 2010 Boston Skillshare!

What: Brew Your Own Kombucha Workshop
When: May 30, 2010, from 12:45-2:15 pm
Where: Simmons College (300 Fenway, Boston, MA 02115)
More info: http://www.bostonskillshare.org/2010/DIY+Kombucha
Donation: $3-$10 sliding scale suggested donation to attend the Boston Skillshare, for a day full of workshops, and food is provided!

The Boston Skillshare is an annual weekend event for people to share and learn skills. Read more about the Boston Skillshare, the 2010 Boston Skillshare, and the workshops at the 2010 Boston Skillshare.

Q&A: Can you brew kombucha with honey?

Q: Can you brew kombucha with honey?

A: Some people swear that brewing with honey works, while others say that brewing with honey doesn't work because of honey's anti-bacterial properties.

Everyone pretty much agrees that brewing with cane sugar works. However, health benefits of other sweeteners often come up as an issue. In addition, taste is another aspect you may want to consider.

Although I have never personally brewed with honey, something to remember is that if you introduce something foreign to the kombucha culture, even if you don't see any immediate short-term effects on the culture, there may be unforeseen long-term effects.

For example, the SCOBY will not survive in the long-term if you brew kombucha using only herbal teas, such as rooibos. However, if you brew kombucha with an herbal tea for only one or two weeks, the culture will most likely survive. Thus, some individuals alternate brewing herbal and non-herbal brews, or brew with a combination of herbal and non-herbal teas. (Read more on brewing with herbal teas at The Different Teas for Your Kombucha Brew).

If you're interested in brewing with honey, I would recommend having a back-up mushroom, such as by storing a spare SCOBY in kombucha made with cane sugar in the fridge.

More on Kombucha and Honey:

• From Gunther Frank: Kombucha Tea: What's All the Hoopla? (around two-thirds down the page, "Can honey be used instead of sugar?")
• Steve Dickman, the co-founder of High Country Kombucha, states that brewing kombucha with honey works in this video (he begins talking about kombucha and honey at time 7:18)
• It's possible according to Happy Herbalist