Kombucha Skillshare and Kombucha Fuel at the UHL Market Stand (Updated July 13, 2010)

*Update: My Kombucha Skillshare is scheduled for 10:45 am this Saturday. Hope to see you there!*
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Join Kombucha Fuel at the UHL Market Stand at the Union Square Farmers Market on July 17th!

What: Kombucha Skillshare (20-25 minutes) and Kombucha Fuel at the UHL Market Stand

When: Saturday, July 17th. Kombucha Fuel at the market stand from 9 am - 1 pm. Kombucha Skillshare at 10:45 am (20-25 minute demo).

Where: UHL Market Stand at the Union Square Farmers Market (1 Union Square, Somerville, MA, 02143)

Description:I will be at the UHL Market Stand from 9 am - 1 pm, to talk to visitors and answer questions about brewing, bottling, and anything kombucha! At 10:45 am, I will lead a Kombucha Skillshare, covering the basics of brewing and bottling the fermented tea kombucha in a 20-25 minute demo.

SCOBYs will be available for those interested in beginning to brew on their own from 9 am - 1 pm. For individuals interested in taking a SCOBY home, bringing a small, clean glass jar would help to facilitate distribution. In spirit of the swap table at the UHL Market Stand, bringing something to swap for the SCOBY would be fun, although it's not required. :)

This demo will be in conjunction with the UHL Market Stand of the Urban Homesteaders' League. They are an awesome group! Read about the Urban Homesteaders' League and check out their blog.

There will also be three other urban homesteading skillshares at the UHL Market Stand on July 17th, see the schedule here.

Bottling and Headroom (Updated July 12, 2010)

***For the update please scroll down to the bottom of this post***

After several readers inquired about leaving headroom when bottling, I felt obligated to experiment.

I had always learned to fill the kombucha all the way to the top when bottling for a secondary fermentation. This stops the activity of the bacteria because of the exclusion of oxygen, while the yeast can continue to ferment the sugars to create CO2 and an effervescent drink, because yeasts can function with or without oxygen (1).

After being prompted to do some experimenting on my own, I left around an inch of headroom in several kombucha bottles for a secondary fermentation. I left the bottles out for a few days, and then I refrigerated them. I didn't open the bottles right away because I already had some kombucha bottles open, but I pulled one out from the refrigerator a week or so later and found that the kombucha bottled with around an inch of headroom was more fizzy than a good number of my previous batches!

Bottling with Headroom
Photo courtesy of Haven Sarah Ripley Daniels

Although Happy Herbalist mentions to fill the kombucha to the top of the bottles in their Brewing Guide (look under "Bottling"), on their Bottling Tips page there is a section "Choosing to leave an airspace." According to their Bottling Tips page, if you leave oxygen and airspace in the bottle and if the temperatures are between 70-85 degrees F, the bacteria will continue to remain active and the kombucha will continue to sour, which makes sense because the bacteria require oxygen.

Meanwhile, the yeasts can function with or without oxygen. However, according to Happy Herbalist, yeasts only form carbon dioxide and fizz when oxygen is present (2). "Carbon dioxide suffocates/diminishes the bacteria, but produce[s] the fizz and sparkling brew. Without oxygen the yeast produce more alcohol...The yeast may be active in temperatures as low as 40F (5C) with or without oxygen" (2). In other words, if you leave headspace when bottling, the yeasts can create more carbon dioxide and fizz because of the oxygen present in the airspace. But if there is no airspace, the ability of the yeasts to produce an effervescent drink is limited because of the limited availability of oxygen.

Unfortunately, I was perfectly happy with this explanation until I returned to this formula from my previous post, Kombucha + Fizz, and could not find oxygen needed in the equation for the yeasts to form carbon dioxide:

The yeasts convert sugar to alcohol + carbon dioxide (3, p. 40)

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

Thus, I am somewhat still confused about the exact relationship between the yeasts, oxygen, carbon dioxide, and kombucha fizz. Perhaps the presence of oxygen helps to encourage the yeasts to form more carbon dioxide and fizz, but its presence is not necessary?

Something to note is that kombucha that is bottled all the way to the top will taste different than kombucha that is bottled with airspace, such as in the amount of fizz produced and in others ways as well, such as the acidity of the drink.

I have not found much information on the recomended amount of airspace if you decide to bottle kombucha this way. However, beer brewers tend to leave 1-2 inches of headspace in their bottles according to this thread. Again, experimentation is key, and do whatever you prefer according to personal preference and taste!

As always, I am continuing to learn more about kombucha day by day, and I hope to share that information. If you have any more information or tips on the bottling process and kombucha fizz, please send the information my way or leave a comment!

All my posts related to bottling can be found here.

References
1. http://www.happyherbalist.com/brewing_kombucha.htm
2. http://www.happyherbalist.com/bottlingtips.aspx
3. Frank, Gunther W. Kombucha - Healthy beverage and natural remedy from the Far East. 4th ed. Austria: Wilhelm Ennsthaler, 1994.

***Update July 12, 2010***

I was able to get to talk to a brewer who brews beer and kombucha. Here is what I learned:

• Confirmation that headroom helps prevent the bottle from exploding from the buildup of carbon dioxide.
• You can still increase the fizz in your brew whether or not you leave headroom in your bottle.
• You won't lose fizz by leaving headspace in the bottle.
• You lose more fizz the more you transfer the kombucha from container to container. You can actually decarbonate your brew by transferring your kombucha from container to container.

In this article from Happy Herbalist, it states that aerobic and anaerobic yeasts in kombucha help to produce carbonation, and that the production of more carbonation than alcohol by both types of yeast is favored when oxygen is present, which is in line with the other Happy Herbalist information (that I am conflicted about) that I provided above.

Part of the reason why there doesn't seem to be a clear answer to the question about whether it is better or not to leave headroom to create more fizz, is because kombucha ferments and SCOBYs contain different strains of bacteria and yeasts and in different proportions. Wild and airborne bacteria and yeasts, which differ according to the location and environment, add even more variation to the mix. Here is one Analysis of a Kombucha Ferment by Happy Herbalist as an example for what may be in your brew.

I personally prefer to bottle with headroom at the moment. But it is up to you, and based on your experiences, to decide whether or not you want to leave headroom in your bottles. I recommend experimenting with both. If anyone wants to share their experiences with bottling, please do so!

Kombucha Drinks Pulled From Whole Foods' Shelves and On Tap

Whole Foods has removed all raw kombucha products from all of their stores. Although it is well known that kombucha contains trace amounts of alcohol, the products were removed due to concerns with slightly elevated alcohol levels because products containing more than .5% alcohol must be labeled with a warning.

Read some articles on the topic:

• Associated Press: Whole Foods removes kombucha drinks from stores
• BevNET.com: Raw Kombucha Products Pulled from Whole Foods' Shelves
• DailyFinance: Whole Foods Pulls Kombucha Teas, Citing Alcohol Content
• Healthy Notes: Kombucha Tea Pulled
• Feed Me Like You Mean It: Whole Foods Stops Selling Real Kombucha

Although kombucha can reach alcohol levels of 2-something %, producing kombucha with less than .5% alcohol is possible. For example, Katalyst Kombucha produces a raw, unpasteurized product with < .5% alcohol content. (Unfortunately, their products have been removed from Whole Foods' shelves for the time being as well). Here is a short discussion thread, Why does my kombucha have high alcohol content?!

Luckily, this recent action does not affect those who home-brew kombucha. And for those of you who don't brew your own, now is the perfect opportunity to start!

There are still plenty of places to purchase kombucha around Boston, MA. Check out my Google map on where to purchase kombucha around the Boston area.

It will be interesting to see what happens, and hopefully things will turn out alright. Stay tuned for updates!

Where to Get Brewing Equipment Around Boston, MA

Need kombucha equipment?

Check out the Modern Homebrew Emporium in Davis Square for all your home-brewing needs (including bottles, bottle caps, bottle cappers, pH strips, and more). I love this place!

Photo thanks to CityVoter

Modern Homebrew Emporium
2304 Massachusetts Ave.
Cambridge, MA 02140
(614) 498-0400

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.