Check out this document which explains exactly what to expect...
This is one of the most common questions - so here's a detailed document that will tell you everything you need to know...
Temperature is the number one factor that usually means homebrewed kombucha takes a little longer than that produced commercially on a larger scale in a controlled environment. The metabolic rate of the organisms is slower when they are cold (like all of us!). There are some things you can do to mitigate this:
Wrap it up! A good old fashioned insulation from a jumper or thick blanket can help the vessel retain the heat energy produced in fermentation. But please make sure it is fresh and clean!
The warmest space in your house is good - some people find joy in keeping the vessel next to hot water tanks/boilers, airing cupboards and the like.
Use a heat mat/jacket. These can be purchased online from homebrew suppliers and are not hugely expensive - it depends on how seriously you are taking your kombucha. A heat mat will not only maintain temperature but also raise it above the ambient, so this is a good solution if you live somewhere very cold.
Remember, wherever you keep your kombucha and whatever you use to keep it warm - ensure the environment and materials are clean to avoid contamination.
What is secondary fermentation?
I want my kombucha to taste of ginger, how do I do that?
How do I make my kombucha fizzy?
Check out all you need to know here...
The liquid provided is the S.C.O.B.Y: an acronym for Symbiotic Culture of Bacteria and Yeast. Your bottle contains a liquid medium of strong sweetened tea liquor replete with the nutrients that feed this culture and keep it active. Kombucha is a unique fermentation which involves both the action of wild yeast and microbes to create its signature flavour in a multi-stage process. As part of this a layer of cellulose is usually created, forming on the surface of the liquid; this bio-film or pellicle is what some people refer to as a physical SCOBY. Be aware that the creation of this jelly-like pancake is neither the goal of fermentation, nor is it a necessary component to the continuation of the fermentation process. Cellulose is produced in layers with every successive cycle of fermentation and can be retained or not when the process is complete. You will rarely be able to prepare a full batch of kombucha with the micros in the pellicle alone - a rule of thumb is that you will always need 10% of the volume of any batch of kombucha you intend to produce to be composed of already fermented liquid, so you should save this each time you produce to ensure you can continue brewing.
You should never refrigerate your starter as it is a living culture and requires a warm environment to stay active - this is for exactly the same reason that the finished kombucha must always remain cold, to ensure the micro-organisms remain dormant and don't make the product volatile or subject to a change in flavour profile from further fermentation or acidification. Culture that has been chilled has a greater propensity to develop mould when employed in future fermentation.
Fermentation for kombucha is very variable - both because the desired flavour profile is quite subjective, but also because environmental factors greatly influence the process and hence each homebrew will progress and develop differently. When brewing on an industrial scale we measure values like pH (acidity) and the gravity (sugar content) of the liquid to chart its progress; but essentially, the most important diagnostic is sensory evaluation. Keep tasting your kombucha and depending on whether you prefer a tart, acidic profile or a sweeter softer feel you would either ferment your batch longer or move on to secondary fermentation. Bear in mind that when you add a substrate to your secondary ferment (either fruit, honey or simply more sugar) that you will bump up the residual sugar; some of this will be consumed in the secondary ferment, but just be aware that if you want something really dry and tart you need to ferment it longer first time around.
For a step-by-step guide, check out our guide here
Tap water has a lot of dissolved minerals which buffer and slow the fermentation making it sluggish. It also contains chlorine by way of a disinfectant and this can produce a taint in beverages.
We recommend using filtered water, or boiling water then waiting for it to cool (boiling the water removes the minerals that might affect your brew).
Of course, if you are not in a position to use filtered water, and would prefer not to boil your water first, tap water is ok to use, but we like to do things as properly as possible, hence, filtered is best!
Depending on the speed of your fermentation (this is affected by the profile of your water - dissolved minerals - the temperature of your environment etc) your kombucha can take 1-4 weeks to ferment. The key here is to keep doing a sensory analysis; taste it often and when you are happy with the flavour profile, it is time to syphon off your liquid for secondary and set aside the remainder to start your new brew. 10-14 days is typical at warm temperatures, but the variability of homebrew environments means this timeframe is often longer; as long as you are happy with the taste and ready to drink you can make this decision at any time. Things to watch out for if you think your brew is struggling in fermentation are: blue mould (often furry in appearance), or failure to produce a bio-film on the surface.
For more info on how long brewing takes, check out this document.
The cellulose layer often develops unevenly and differently depending on the action of the bacteria - it is gluconacetobacter that are responsible for this action primarily in most cases, but different bacteria and strains of yeast will create bio-films of a varying nature, depending on which is predominating over time. If you hold on to this cellulose, you will notice that it develops and changes somewhat in colour and structure; this is nothing to worry about, but you can also get rid of it at any time should you so choose - remember that it is really only a by-product of fermentation and not necessary to brew with; in addition, a fresh layer will develop with each successive fermentation.
There will be a light carbonation present in your kombucha while brewing as the organisms are always producing CO2, but at warmer temperatures and while not under pressure, this will dissipate. That is why you place your liquid in a sealed environment under pressure for secondary fermentation, allowing the gas to be dissolved into the liquid to make your drink fizzy. This carbonation remains dissolved better at low temperatures, hence why things with gas in them often fizz up more when warm and why it is best you chill your kombucha before drinking. Kombucha is a slow gentle ferment and it is not always obviously actively producing gas as in more vigorous fermentations (beer, wine etc), so don’t be surprised (or dismayed) if you don’t see any gas appear during the 40 seconds you observed it on a given day.
The brown mass is usually flocculated yeast - this happens once the yeast has performed it's primary function earlier in the ferment and the pH drops, it is stifled a little and the microbial culture takes over converting the alcohol to acids.
The organic acids in kombucha make it naturally tart and I would suggest your fermentation is almost done if the body is light as this would imply that most of the sugar has fermented out. You can add more body and sweetness back with flavouring in secondary fermentation.
The clarity or brightness of your kombucha will depend on a few factors. Live kombucha has a mixed culture of yeast and microbes in suspension and the metabolic processes in mixed culture fermentation cause the liquid to be turbid (hazy). There are also often strands of darker coloured yeast, bits of tea dust and aretfacts of cellulose that come from the pellicle which usually floats on the surface of the fermenting liquid. There are a few things you can do to have a clearer final product ready for drinking. A rough filtration as you transfer from primary fermentation (we recommend recycled coffee filter paper or some washable muslin/cheese cloth) will remove any large unsightly floating particles as you begin your secondary fermentation. The ingredients you use in your flavouring will also affect the cloudiness of the final beverage - whole, crushed or pureed fruit for example. There are ways around this, should you so wish - try making a separate infusion in hot liquid with your ingredients and then sieving this before adding to the final kombucha or use high quality essence or extract to add aroma and flavour. Always chill your finished kombucha well before drinking; cold filtration is a naturally great way to drop anything in suspension to the bottom of your serving vessel allowing you to simply pour gently and steadily to leave this behind and not carry it over in into your glass.
For more advice on your secondary fermentation, check out our page here.