When will I know my kombucha is ready to drink/bottle?

A frequently asked question:

• When will I know my kombucha is ready to drink/bottle?

There are many indicators of kombucha progress, among them: time, taste, effervescence, appearance, mother formation, and pH reading.

Time: as you let your kombucha brew, it will start out as a sweet tea, then become delicious fizzy kombucha, and one it is past due will turn into a flat vinegar. Kombucha brewed at lower temperatures will take longer to brew, and kombucha made with more starter will generally finish early. For more information, see this post on brew duration.

Taste and effervescence: taste your kombucha with a straw so as not to disturb the SCOBY, bottle when the kombucha is slightly too sweet if you're going to let it carbonate sit and carbonate, and don't let your kombucha sit so long as to become disagreeably sour. For more information, see this post on taste-testing brews.

Appearance: When made with black tea, a brew will start off as a reddish-orange hue and take on a pale amber tint when it approaches maturity. Simiarly, green tea takes on a frosty yellow appearance when made into kombucha. Once you get used to gauging the progress of a brew by color, it is a quick was to quickly survey progress.

Variation in kombucha color. From left to right: fresh black tea; kombucha made from black tea ready to be bottled; kombucha made from green tea ready to be bottled.

Mother Formation: In an ideal brew, a new mother will have fully formed on the surface of a brew by the time the liquid has reached peak effervescence and choice flavor. In reality, a fully-formed mother may sometimes appear early; other times, growing a mature mother -- that is, one which is consistently greater than a half-inch in thickness with minimal translucency -- can occasionally take more than one brew cycle to achieve. So it is best to acknowledge mother formation as a reliable indicator of progress, but also keep in mind that it may not be entirely reliable.

pH reading: Since kombucha becomes gradually more acidic as it brews, some people take pH readings of their kombucha to track its progress. There are various resources concerning this practice available, at both HappyHerbalist.com and Organic-Kombucha.com. The general consensus seems to be that sweet tea starts with a pH around 4.0-5.0, and finished kombucha should clock in at just under a pH of 3.0. Personally I don't use this technique because I find it does not account for the sweetness of the brew, but it is a very good way of keeping track of things in a controlled setting.

Is that mold on my kombucha?

Mold on kombucha isn't a huge problem. Of all the stories I've heard about people getting ill from contaminated kombucha, investigation reveals most such stories to be urban legends. This is a rational approach to kombucha contamination.

When mold appears on kombucha, it will almost always grow on the surface of your mother. It will look like other molds you've seen before: fuzzy flushes of growth coloured brown, green, cyan, or black. If you can spot mold on bread or cheese, then rest easy -- kombucha contamination doesn't look much different.

When you find mold on your kombucha, it's safest to dump the batch out and start fresh. Discard the contaminated culture. I have heard of people cutting moldy sections from mothers and re-using the rest; this strikes me as being unduly haphazard given how quickly SCOBYs reproduce. If you have several brews going simultaneously and one goes bad, keep the others in check -- mold spores do travel, and the other brew may be at risk.

And now, here are some images of mold growing on kombucha cultures:

photo courtesy of Organic-Kombucha.com

photo courtesy of Organic-Kombucha.com

photo courtesy of Happy Herbalist

Is my kombucha too sweet/sour?

Two frequently asked questions:

• Is my kombucha too sweet?
• Is my kombucha too sour?

Kombucha brews start off as sweet tea and end up as effervescent, acidic, somewhat dry kombucha. If a ferment is allowed to brew past its ideal drinking stage, it eventually looses its carbonation, becomes very acidic, and more or less starts to resemble apple cider vinegar.

Generally, it can be said that your kombucha will be ready when it tastes good to you. You can safely sample an ongoing kombucha ferment by using a straight straw, sneaking it around the edge of the SCOBY baby at the top of the brew as best you can not to disturb it, and taking  a sip from the bottom of the brew vessel. Ongoing brews cannot be trusted to be homogeneous; they will tend to be more acidic near the surface and more raw toward the bottom.

If you plan to bottle your kombucha and let it sit somewhere warm before drinking it in order to give it time to carbonate. If this is the case, you may consider bottling your kombucha two or three days before you estimate it to be at its prime drinking state. This kombucha will be a bit sweeter and thus contain more unprocessed sugar for the yeast to feed on while carbonating. This is an entirely optional measure; alternatively, you might add a teaspoon or so of sugar before bottling.

If your kombucha is deemed "too sour," there's not much you can do to reverse it. It is better to keep a close on your brew than neglect it, as once it is past a state of preferred flavor and effervescence, it will gradually brew into a vinegar within two weeks. One might attempt to cover up for a prolonged brew by adding addition sugars or flavors, or allowing it to refrigerate for several weeks to mellow and dry out in flavor. These methods, although haphazard, may result in a palatable beverage.

How long will my brew take?

A frequently asked question:

• How long will my brew take?

This mostly depends on (1) the temperature at which it is brewing, (2) the quality of your mother, and (3) the quantity of starter added at the beginning of the brew.

The sweet spot for fermentation is generally around 80°F/26°C. Kombucha brews left in consistently cooler temperatures (down to 65°F/18°C) can take up a month to complete, whereas warmed kombucha brews (up to 85°F) can take no more than three days. Below 64°F/18°C, microbiotic activity slows to a temporary halt -- refrigerated komucha won't brew until it's brought to warmer temperatures again. Brews made between 70-79°F/21-26°C should take one to two weeks; brews made between 80-85°F/26-30°C will take three to seven days. Ferments above 85°F/30°C result in brews that are more acidic, less mellow, and less carbonated.

Different kombucha cultures and mothers will have unique properties due to variation in microbiotic action. Some mothers simply brew slower -- although this is not exclusively indicative of a bad or dying mother, healthy cultures tend to brew consistently at a steady pace; a two-week turnover should be expected from a healthy brew kept at ideal temperatures.

Finally: the amount of starter added at the beginning of a brew can shorter or prolong brew time. The reasoning behind this is simple: more starter means a lower proportion of tea, thus less of that ingredient needs to be processed by the kombucha culture before it is deemed ready for bottling. Some continuous brew systems (in which sweet tea is added to an ongoing brew every few days after a proportionate quantity of kombucha has been drawn out for bottling) average up to 50% starter when tea is added, and thus brew time can be as short as three days. In this case, however, the "starter" is actually kombucha ready to be siphoned off and bottled; this is in contrast to conventional kombucha "starter," which is a prolonged vinegary  ferment of tea which has long passed it ideal time for bottling.