A bit about the 'bucha
We have entertained the theories about where kombucha came from and a bit of where it's turned up throughout history. Now it's time to get scientific. What makes kombucha so awesome? It all starts with fermentation. By definition, fermentation means the chemical breakdown of a substance by bacteria, yeasts, or other microorganisms, typically involving effervescence and the giving off of heat. It's a technique that has been used since as early as 7200 B.C. to preserve meat, vegetables, and fruits.
In regards to kombucha the fermentation process involves the SCOBY and the tea, specifically the sugar in the tea. The SCOBY is introduced to the tea and soon begins to form a film on top of the tea as to get as much contact with the nutritent medium (the tea) as possible. The tea is left out covered with a breathable cloth - and the magic of a complex chemical dance begins. Acetic acid bacteria, such as Gluconacetobacter and Acetobacter, and lactic acid bacteria, such as Lactobacillus, work with several yeast populations to inhibit the growth of potential contaminating bacteria. Over a period of about seven to 10 days, they convert the sugar and tea to a lightly carbonated, slightly sour drink composed of amino acids, vitamins and enzymes - that is DELICOUS and NUTRITIOUS!
Bill Of Materials
Brewing kombucha at home is simple, cost-effective, and rewarding. There are just a few things that you'll need to succeed (many of which you probably already have). The first being a clean spot to brew - I brew my kombucha in my kitchen cupboards because it's a cool, undisturbed spot with little to no sunlight.
The next item on the list of "must haves" for brewing your own kombucha is a fermentation vessel. Generally glass is widely accepted as the best material to brew kombucha in at home. A large gallon sized glass jar is perfect, but you can be creative. It's typically suggested to avoid prolonged contact with metal, as it can interfere with the SCOBY and brew in general - however, if you have stainless stell that is higher than grade 305 then you'll be just fine. Some brewers like to utilize a fermentation vessel that has a spout on the bottom; this helps ease of bottling later on and can lend itself to a "continuous brew" style more easily (we'll touch on these different styles later).
// picture of fermentation vessels in kitchen cupboard
Of course, you won't be able to brew kombucha without the SCOBY and a little bit of starter liquid (essentially just kombucha to keep the SCOBY happy and give your brew a bit of a kick start). You can obtain a SCOBY from your local friendly kombucha pusher - or there are a number of reputable brands to buy SCOBY's from (Amazon has quite a few, of course). Not all SCOBY are created equal, so keep a keen eye out for anything that might look "weird" (we'll cover what is considered to look "weird" in later chapters).
// picture of SCOBY
A few more essentials for brewing a nice kombucha are tea, sugar, and leaves. The types of teas and sugars that can be used are vast and of course we'll cover them all in detail in later chapters. Pure black, green, white, and oolong tea are generally considered to be the "top dogs" and most kombuch brewers use these, or combinations of them, for various kombucha brews. Sugar is another area that deserves a deeper dive, but ultimately pure cane sugar is the most effecient source of surcrose to convert the yeasts. Water is a bit of a similar topic, but basically clean, filtered water is what you want here.
// picture of tea, sugar, water
These next supplies aren't exactly required, but depending on your goals with brewing kombucha they might be helpful. Glass swing top bottles - these are used for the "second fermentation", which is when other flavorings can be introduced to the kombucha brew. These bottles come in various sizes and shapes and can be reused over and over. Funnel - it's purpose is pretty self explanatory; when transfering your kombucha to swing top bottles this is very much a requirement. Fruit/herbs/flavorings - this is another pretty obvious resource for kombuchah brewing. During the "second fermentation" you can introduce fruits (dried and frozen are what I typically use), herbs, flavorings, spices, etc. to add more flavor and nutrients to your brew.
// picture of swing top bottles, funnel, and fruits/flavors
Birds Eye View
Essentially the process is extremely simple; just a little bit of work and a little bit of waiting around to let mother nature take the wheel. We will dig more into each specific component, but we're going to walk through a typical flow for a full brew at a birds eye level now. First you'll need to brew the tea, which can vary with types of teas and types of sugars one might choose. Next is the introduction of the SCOBY and starter tea (just a bit of 'bucha to kick things off nicely) to the tea that was just brewed. Now it's a waiting game - some folks like to use pH strips to determine when the brew is at their desired level, others choose to continually taste a sip every day until they're at the right spot - this is another area where variance will be encountered, as everyone prefers a slightly different tang/acidity/sweetness level. At this point, the brew is done - unless you'd like to go for a second fermentation to add some fizz; this is also the point at which you would introduce flavorings/fruits/spices. The second fermentation length also varies, as different fruits/spices/flavorings will add more/less sugar and speed up fermentation - too long of a second fermentation can lead to 'bucha that is TOO fizzy and can rapidly expel itself from the swing top bottle once pressure is relieved (this can make a HUGE mess - pro tip: cover the top of the bottle with a rag when opening, cuts down on the potential splatter distance by a great amount).
Cleanliness
As with any type of fermentation, we are dealing with bacteria and yeast - there's always a potential for bacteria/yeast/etc. that we do not desire to make it's way into a brew. This is why cleanliness is paramount in brewing kombucha. As long as we ensure that our working space, tools, containers, and hands are clean then we can feel perfectly happy that our brews have the best shot possible. Having the kombucha brewing in a clean spot also ensures that outside contaimants, whether from some old fruit/old bread/outside/etc, do not make their way into our brew. Contaminants are not fairly common and we will dig into what to look out for in a later chapter, but as always - "when in doubt, throw it out" is always a good motto to remember with fermentation.