The concept is very simple: make real tea (from Camellia sinensis; herbal teas won't work that well unless you mix them with actual tea), add sugar and finally a scoby. This stands for Symbiotic Culture Of Bacteria and Yeast, meaning that bacteria and yeast strains live together in a complex, mutually supportive community. The scoby resembles (in my opinion) a rubber-like pancake that floats on the tea, although some people call it a mushroom as it also resembles the smooth, thick body of a mushroom. It requires oxygen to change the tea into Kombucha, which is why the jar can't be hermetically closed. We bought some today and it tastes very much like the shrubs my wife's been making. It has a nice acidic flavor and is carbonated to boot, thanks to the yeast. For pictures, take a look here (I don't have the copyright to any of those, so I'm just linking to Google images).
Tea is obviously a critical component here and in most cases people will use black, oolong, green or white tea or some combination. The scoby really loves black tea from what I've read, but oolong and green teas work well by themselves as well. Aside from tea the only other thing you really need to obtain is the scoby (assuming you have sugar). There are lots of ways:
- Buy a dehydrated scoby online, which of course has to be rehydrated;
- Buy or get a living scoby , which can be added immediately to your sweetened tea;
- Use a commercial bottle of Kombucha, that's not been pasteurized. You can add this to the sweet tea and it'll start growing the scoby from scratch.
The last method has apparently not been very successful with most commercial Kombuchas, as they've either been pasteurized or additives have been added which killed off the yeast and bacteria. Fortunately at a natural food store nearby I found sound locally made Kombucha (from Unity Vibration in Ypsilanti, MI) which is raw (and thus not pasteurized). It has a nice amount of yeast at the bottom, which would be the ideal starter. The nice thing about fermenting Kombucha is that in general it can be ready after only 7 days. For once that's refreshing as most other ferments take weeks or months before tasting just right.
How to make Kombucha
For 1 gallon of Kombucha you generally need about 13 cups of filtered water (no chlorine, chloramines or fluoride), 1 cup of sugar, 2 tablespoons of loose tea (or 8 tea bags) and about 2 cups of starter tea (previously "brewed" Kombucha or from a commercial bottle). Make the tea, add sugar until it's dissolved, let it cool down to room temperature in a glass jar and add the starter tea. If you already have a scoby, just make a gallon of sweet tea and add the scoby to the cooled down liquid.
The jar shouldn't be closed with a lid (this would prevent oxygen from entering the jar), but with a permeable towel, coffee filter or folded piece of cheesecloth attached with a rubber band. The idea is that you want oxygen to get in, but keep fruit flies and other critters out. Wait 7 days and start tasting. If it's too sweet, let it go longer and taste every day until it's to your liking. Obviously ensure everything is sanitary and avoid using any sort of metal on a scoby (utensils, rings on your fingers, etc) as it would negatively impact the culture.
The alcohol content of the kombucha is usually less than 1% but increases with fermentation time.
Etymology
The word Konbucha (yes, with an "n") originates from Japan but its meaning has changed. The Japanese version is made from regular or powdered kombu kelp mixed with green tea and poured over hot water. This kelp contains rich minerals and is chock full of umami flavors. When people in western culture think of Kombucha, they are talking about acidic fermented tea originating from northeast China and Russia containing various bacteria and yeasts. The Japanese name for what we here know as kombucha is kōcha kinoko 紅茶キノコ ('black tea mushroom'). The original kelp tea konbucha (昆布茶) can also be read correctly in Japanese as kobucha, omitting the m/n sound altogether. (see here)
So how did we associate the word kombucha with this fungal tea (that makes it sounds sooooo appealing)? No one is really certain, but there is definitely a lot of conjecture surrounding the subject. One often touted is that the thick gelatinous scoby resembles a clump of seaweed or kelp. Depending on the source you go with, Kombucha was first used in English in the 1990s. with the potentially first occurrence in 1991.
What's in a scoby?
The yeasts may contain one or more of these: Saccharomyces cerevisiae, Brettanomyces bruxellensis, Candida stellata, Schizosaccharomyces pombe, and Zygosaccharomyces bailii.
The bacteria almost always include Gluconacetobacter xylinus, which ferments alcohols produced by the yeasts into acetic (a component of vinegar) and other acids. This in itself increases the acidity and limits ethanol content as alcohol producing yeasts don't thrive in very acidic conditions. This bacterium has been reported for most or all of the physical structure of the scoby.