This site offers an alternative, more scientific view to kombucha tea fermenting and a lot of nuances one has to be aware of when brewing kombucha safely at home.
There are many kombucha tea fan sites out there and they are all great, but one thing that has been annoying me is the way the kombucha is treated like a food item. Yes, kombucha IS a food item but there’s more to that. Kombucha is a living bacteria culture. 99% of the kombucha related pages make an impression that brewing kombucha tea is like making a cake — a somewhat trivial operation. They mostly present kombucha recipes. But a recipe is by default a simple description like “take one cup of flour, add two eggs, mix with milk, etc”. And the result is so Yummi.. Well..
Kombucha Science will go much further than simply presenting a kombucha tea recipe — we are going to find out what makes kombucha culture tick. We try to understand how we can get the best out of kombucha, and most importantly — what is needed for healthy and SAFE drink. We try to give the kombucha culture the respect it deserves. You are growing LIVING THINGS when making kombucha tea — it’s not a mechanical operation that can be presented as yet another recipe.
What is Kombucha Tea?
Kombucha (Kombu cha, fungus tea, mushroom tea, scoby tea, mushroom drink, kargasok tea, manchurian mushroom tea) is a fermented drink where in result of bacteria and yeast activity health-beneficial substances are created. Kombucha is basically a symbiotic mix of certain kinds of bacteria and yeast. So, if you are brewing kombucha tea at home you are basically growing bacteria — a challenge worthy of scientific laboratory. Luckily, we don’t need scientific facilities to successfully grow kombucha because the kombucha symbiotic culture is very tough and resistant to outside bacteria invasion. That’s why laboratory-grade cleanliness and precision is not necessary for DIY kombucha tea success.
What is SCOBY?
Scoby (Symbiotic Colony Of Bacteria and Yeast) is one of great misconceptions regarding to kombucha tea. Scoby is also called kombucha mother, tea mushroom or kombucha fungus. It is often believed that scoby IS the reason for kombucha fermenting. Kombucha scoby is often referred as tea fungus (and kombucha drink is called fungus tea) or mushroom tea. Well, kombucha tea symbiotic culture has nothing to do with fungal lifeforms or mushrooms. Nothing what-so-ever. Calling Kombucha scoby a fungus or mushroom is a pure misconception. And there are more of those around.
It’s kind of understandable that kombucha scoby is a thing of misconception because, well, it’s there for all to see. And it grows thicker when time passes. It looks to be alive — a separate living entity.
Kombucha tea is an ancient drink and countless eyes have stared at the whitish blob that floats on the surface of kombucha tea ferment, and tough that this blob IS the essence of kombucha. Well, it is not. And today the misconception largely persist — that the scoby is essential to Kombucha brewing. Lets make one thing very clear.
Scoby is not necessary for kombucha brewing
Scoby is a waste product of the fermenting process. Scoby is simply bacteria and yeast impregnated blob of bacterial cellulose. As such, it can be used to start new kombucha brew — but so does a piece of cardboard impregnated with kombucha tea. Scoby has some importance in a brewing process in a sense that health of the brew can be monitored by watching scoby growth. Healthy kombucha always produces thick, strong, whitish scoby.
If Scoby Is Not Important for Brewing Kombucha Tea, Then What Is?
Only thing you do need for starting to brew your own kombucha tea fermented drink is kombucha starter tea. Starter tea is nothing more than already fermented kombucha tea. It would be best, if the starter liquid has fermented for quite a long time and is very acidic — basically kombucha vinegar. Of course kombucha scoby can also be used as a starter for new brew but value of the scoby in this sense is nothing more, than it contains same bacteria and yeast, just like fermented kombucha tea itself. It is simply kind of a sponge for the kombucha lifeforms.
Best starter tea is very acidic. That’s why your fresh brew will be somewhat acidic even at the beginning of the fermenting. Acidity is extremely important for maintaining healthy kombucha bacterial culture AND for being safe to drink. Acidity of the brew right from the start is ONLY safeguard against harmful bacteria that would love to feed on your sugary tea too.
For safe and healthy kombucha tea reasonable acidity must always be present during fermenting!
One should always have some dedicated starter tea at hand for the case the main patch gets destroyed for any reason (more on that later). Ultra-high quality starer tea is actually extremely easy to make: just “forget” some jars with the fermenting kombucha tea somewhere in your kitchen — for months. All the ferment turns to kombucha vinegar that way that is very acidic AND consists of extremely potent bacteria for starting new patches. You don’t have to worry about your backup kombucha culture dying to lack of nutrients, because the culture goes to kind-of sleeping mode and can remain viable for months or even years (I have not managed to starve a starter-tea batch to death yet).
Fact is, that kind of pure-vinegar kombucha is best kombucha starter kit you can have.
What Does Kombucha Culture Need to Be a Success?
I promised at the beginning of this page that we treat the kombucha here with the respect it deserves — with the respect that every living creature deserves. Raw kombucha tea ferment is a living thing — it consists of millions of tiny bacteria and yeast who live and multiply just like any other living thing on Earth. A scientifically minded kombucha brewer needs to ask what it is, that all the living things need? All living things need:
- Food (kind of obvious)
- Warmth (even polar bears need warmth)
- Suitable environment (it depends, what is suitable for fish, ain’t for men)
When you can manage those three points well, you will be a successful brewer of healthy kombucha, get those wrong and you will be brewer of bad kombucha that is a potential health risk. It would be extremely unlikely that a seasoned brewer would drink a bad patch, but what if you have never tasted the kombucha before — how would you know that you are brewing an unhealthy drink instead of a healthy one?
One of the main kombucha dangers is the situation when an inexperienced brewer drinks a ferment gone wrong, and is not aware of the fact. That’s why you need the proper know-how even before you start. For making kombucha you need:
Healthy kombucha starter tea
Kombucha bacterial and yeast cultures need Food, Warmth and Suitable environment
Food — Energy Source for Kombucha
There is one universal food source for almost all bacterial lifeforms — it is sugar. The word ‘sugar’ is actually little too superficial for our purposes. Sugar most often (but not always!) means sucrose. Sucrose is a carbohydrate most often extracted from sugar cane. Yep, it’s your everyday refined white table sugar. In the presence of acids (or by the suitable microbiological activity in a solution) sucrose molecule divides into fructose and glucose. Fructose is a carbohydrate commonly found in plants and fruits. Glucose is THE energy source for the bacteria and cells of the multi-cellular organisms (yes, all your body cells get their energy from glucose).
Living cells also need other chemicals beside the energy source. That is when the term ‘food’ gets to be quite difficult to define. Humankind will never agree what is a ‘proper’ food for humans. It is little easier to define what nutrients a human organism needs. Some nutrients in some foods may not be available to the body even if the food contains them. Well, guess it’s a matter of what works and what doesn’t. With kombucha it’s the same. There’s thousands of years of experience that kombucha culture will get all the needed nutrients and trace elements from tea. So, lets give the kombucha what it needs.
As it is a Kombucha Science page we can go little deeper than that. Well, it’s a kombucha fact that the energy comes from sugar and all the necessary elements from tea. There’s one element in particular that kombucha needs from the tea. It is potassium. The main energy transport mechanism in cells is called sodium-potassium pump. It’s a basic mechanism of critical importance for living cells. Sodium can be found in water but potassium must usually be added when growing bacteria. Think about that, if you’re going to grow Water Kefir. In that case you usually should introduce ‘some fruit’ to the brewing solution. Make sure that the fruit you use contains plenty of potassium. Kombucha culture needs energy source (sugar), potassium, sodium and plenty of other chemicals and trace elements. Tea has them all.
Which Tea to Use?
Use simplest quality-brand non-scented black tea. You can experiment with other teas later when you are experienced kombucha brewer with ample starter tea backup stock.
All lifeforms need warmth to survive and to prosper. Chemical activity inside the living cells is directly dependent of their environment temperature. Most bacteria need a certain temperature that is optimal for them but are usually able to cope with relatively wide temperature range. Kombucha ferment has many different bacteria strains and yeasts — what is optimal for one life form, my not be for another. Yeast will usually remain active in lower temperature range than bacteria.
It is safe to say that what is pleasant for humans, is pleasant for kombucha. You should make your kombucha in a place that is warmer than 20 degrees Celsius (anything between 20 and 30 is fine) It is often written that 23 degrees is optimal. I tend to agree. Note that you must never let your kombucha tea ferment get warmer than 35 degrees or the culture will die!! Stay below 30 degrees to be safe.
Below 19 degrees the fermenting activity will be quite low. My backup kombucha starter tea jars have often been in somewhat colder place (10–15 degrees) and have grown thick scobys despite the low temperature.
Actually I think that keeping very acidic and vinegary kombucha starter tea at lower temperatures makes absolutely excellent and potent kombucha starter. Just put your backup starter tea to a cool corner and leave it there for months.
Living cells need food and warmth but there’s other physical properties that need to be suitable for any particular bacteria culture. Mammals need oxygen, for example, but plants need light and CO2. Kombucha bacterial strains need acidic environment. Acidity or alkalinity is a condition in a solution when there’s H+ or OH– ions abundance respectively. Most bacteria are happy in an alkaline environment including strains that pose health risk to humans. Among acid-loving bacteria there’s almost none that are harmful to us (there are few exceptions!). That’s why it is so important to maintain the acidity of the kombucha brew. If you let the acidity to go too low (PH of the brewing tea is too high) by diluting the fresh batch with too much tea and too little starter tea (or relatively low acidity starter tea) then you have created a condition where pathogens may take a foothold. Maintaining high acidity of the kombucha brew is your only safeguard against unwanted bacteria! You may have superb cleanliness in your kitchen but that does NOT guarantee that you don’t have harmful bacteria around.
One of the great strengths of the kombucha ferments is the fact that they can be brewed in less than sanitary conditions (think of the peasants some five hundred years ago) and still be extremely safe to drink. You need to provide an acidic environment to your kombucha culture and no pathogen cannot thrive there because of the unfavorable conditions and because the good kombucha strains have already invaded the living space of the brew.
Ok, kombucha needs acidic environment, what else? As it happens, kombucha strains are aerobic (‘oxygen loving’) bacteria, so they need oxygen. And if all conditions that kombucha ferment NEEDS are fulfilled there’s still something more. A living environment (either for bacteria, fish or men) must not contain any poisons! Lets think it trough what we can do to provide oxygen-rich and poison free environment for our health-giving kombucha culture.
Things That Are Dangerous to kombucha
What substances are poisonous to men? Who knows, the list is too long to even attempt to put together. Same goes for bacteria. Except that lots of things that are relatively safe for a men is deadly poison to bacteria. It is some advantage to be a multi-cellular structured organism. All kidding aside, some relatively common substances that humans use for their own purposes are dangerous to bacteria (we try to kill bad bacteria for healthy living). But in case of kombucha, we try to GROW bacteria instead of trying to get rid of them.
Chlorine is certainly poisonous to kombucha. And fluoride. You need to know if your water company puts those into your drinking water. If they do, there may be a way to try to purify the water by boiling it. Or using some sort of water filters (silver ion filters are definitely no-go, read below).
I’m sorry, but I actually don’t know it those methods would be helpful to you (I use well water for my kombucha). Guess it depends of how much this-or-that is in your water. If I knew that my mains water was chlorinated or there was fluoride added I would start looking for another water source for my kombucha tea making. There may be other things in your water that are lethal to kombucha. Old plumbing, led fittings in an old house, metal deposits in the water front your drinking water is pumped from, etc.
You just need to be lucky enough to have good and suitable water for kombucha brewing. If you don’t have it, you can use store-brought water. Be aware that some mineral waters in the stores also contain fluoride.
Sugar used may also contain something that is poison to kombucha. Do you actually know where, how, when and in what conditions your table-sugar was manufactured? Let’s face it, you don’t. Even if you by some major-brand sugar, you don’t. What they sell today, is not the same they sold yesterday.
Plants get opened and closed, business interests may dictate that today your sugar comes from one part of the world today, tomorrow from another. There’s just no way to know!
Actually, the possibility that ordinary refined white sugar contains something harmful to kombucha is rather low. If you have problems with kombucha making, other components must be higher up in the possible culprit list than the sugar.
With sugar it’s the same as with water — you need to be somewhat lucky to have suitable stuff for your kombucha. And the same goes, you guessed it, for tea. When you try to make that super-healthy fermented kombucha ‘mushroom’ tea brew, you are actually at the mercy of the whole tea industry — where is the tea grown, how it is treated when it grows, fertilizers, pest-poisons, harvesting, conservating, transporting. A Million things. All you can do is choose a respectable brand and hope for the best.
You also need to choose suitable tea sort for kombucha brewing. Use simple black non-scented tea (tea scenting is again probably something that is poison to the kombucha).
There you have it, water, tea and sugar may contain something that is bad for kombucha but at the same time be (relatively) harmless to you. When luck is on your side, you wont have no problems with any of those substances, but be aware of the possible problem sources.
use refined white sugar
use quality-brand simple black tea
water must be chemically untreated
More Things to Consider About Kombucha Health
Even if you have good water, sugar and tea, you should not accidentally introduce something poisonous to the fermenting tea. Kombucha is very acidic, but acids react with different materials — particularly with metals.
Dissolved metal ions in a solution are good for disinfecting. And that is exactly the reason you don’t want any metal ions to your kombucha tea. Don’t even attempt to brew kombucha when you have silver-based water purification filter installed in your house water supply circuit. Silver-containing filters are extremely effective in killing all the bacterial lifeforms — silver-filtered water may be safe for you to drink but for kombucha it’s a death-sentence.
From metals, silver is the most dangerous to the your kombucha tea bacterial cultures. Don’t handle kombucha scoby when wearing a silver jewelry — even something as simple as a ring! Silver ions are extremely deadly to all bacteria. That’s why silver has been used as an ancient water purificator. Drop a silver coin to a bucket of water and the silver ions will kill all the bacteria in it. I’m not sure about possible effects of gold jewelry tough as gold is extremely difficult to dissolve and is one of the most inert substances around.
You should be able to boil ordinary tea for kombucha brewing in a metal pot (coper, iron or aluminum), but as the black tea itself is somewhat acidic, I would not recommend it. You SHOULD NOT use iron, aluminum or copper pots or utensils for fermenting acidic kombucha tea.
There is a misconception presented in many kombucha websites. It goes something like this: “you must never let any metal touch the kombucha”. That statement IS true regards to the kombucha fermenting and almost all ordinary metals, EXCEPT stainless steel.
Stainless steel is completely safe as a brewing vessel material and for utensil material! Stainless steel is THE material for the food industry! And it is particularly resistant to acids! Only extremely alkaline and oxen-free environments pose a challenge to the stainless steel. But kombucha ferment is acidic and oxygen rich!
Glass is completely safe for kombucha brewing and has to be the best option regarding to chemical stability. However, you should make sure not to use any decorative glass or tinted glass, because they may have lead or other metals in the glass mix that pose a health risk to kombucha and to the drinker! Glass is the best material for your kombucha brewing vessel only if you are sure that the glass mix in question is safe. Lots of things get manufactured today in China. Are you absolutely sure that the nice jug you have does not contain any hazardous metals? I’m probably too cautious here — simple plain non-tinted glass is probably safe 99% of times, even if it comes from China.
Ceramics MAY be acceptable for kombucha fermenting only if you are sure that they are food-grade and acid-proof. Same warnings apply as for the glass but overall, there’s much more ceramic coatings that may contain hazardous metals and are a healt risk even for ordinary food usage, than in case of glassware. My simple advice would be — stay away from ceramics for kombucha brewing if you aren’t absolutely sure that the material in hand is safe to use.
Plastic is another option for brewing vessels. Plastic CAN be excellent choice but.. and there are many of those buts. What is this ‘plastic’ anyway? Who knows. There are hundreds of different kinds of plastics that all have different mechanical, physical and chemical properties, different manufacturing methods, purposes, cost and so on. Are you competent in the world of plastics? Do you really know what goes into the manufacturing process of any given plastic today? And tomorrow? Do you follow the changing manufacturing methods and can guess, what goes on in the mind of plastic engineers at the industrial scale where low cost is paramount? Take it as you will, but I don’t trust the plastic materials too much. They are all manufactured from “The Oil”.
If you decide to buy a plastic fermenting vessel (either for kombucha or other stuff, like homemade beer for example) then obtaining a quality product that you KNOW to be safe may be a difficult process. And the cost may be more than you thought it would be. Quality does not come cheap, and it goes for plastics too. If you buy a class vessel you surely get more for less money, if ultimate chemical inertness is the main goal. But lets face it, very big glass vessels are kind of rare. And they are kind of unsafe. Imagine a 40 liter brewing vessel break in your kitchen. What a mess! And very dangerous too.
Plastics are safe at least in that sense that they don’t break so easily. In the end of the day, plastic vessel may be your best bet. I would recommend the stainless steel as the first choice, but big stainless steel vats are really expensive!
There is one more extremely interesting alternative to above-mentioned brewing vessel materials. You would never guess it. Its wood. Wood is kind of oldest plastic around (wood is a natural polymer, you know!). Well, I have never used a wooden vessel for kombucha brewing (or for brewing anything, for that matter) that’s why I cant recommend it first-hand but wood got to be one of the most interesting choices there is! Many woods have excellent tried-and-true safety record. Wood is natural and cool material!
Still, for a scientifically-minded kombucha brewer who starts to run large batches soon nothing beats professional stainless steel brewing vessels. As the stainless steel is so inert, modern, unbreakable, and is standard choice for food industry, it just got to be the recommended material of the Kombucha Science.
Well, stainless steel needs oxygen to be chemically resistant and kombucha needs oxygen for its metabolism — how can we make sure that there is plenty of oxygen available for the kombucha tea ferment?
Stainless steel is completely safe for kombucha making
How To Provide Oxygen for Kombucha
Kombucha tea needs oxygen — it’s an aerobic ferment. Most obvious oxygen supply is, of course, air. We need to make sure that there’s relatively good access for the air’s oxygen to the kombucha. A most obvious ‘no’ would be to use a airtight lid with your kombucha tea brewing container. We need to let the air in, but keep the dust and bugs out from our healthy kombucha ‘wonder drink’.
Simplest solution for providing plenty of oxygen to the kombucha tea is to use some sort of breathable material for covering the kombucha brewing vessels. In case of the expendable kombucha ferments (small patches for testing the suitability of a new tea brand, for example) a simple piece of paper is usually enough to cover the jar. Alternatively, a jar could just be left open. That may not be an option, if you live in a relatively warm climates. In northern parts of the world on the other hand, there’s for about half of the year completely bug-free environment (I wish I could say that regarding to computers too, for they are never ‘bug-free’, it seems). If you have no dust problem then leaving the jar open for test patches is a viable option.
Actually (and I know it will sound kind of wild), if you really have no problems with bugs, it is actually possible to leave even your main brewing container open. Healthy kombucha tea ferment always grows scoby at the top of the liquid. One of the reasons the scoby is useful for kombucha brewing is the fact, that it protects the ferment mechanically from dust and airborne lifeforms. That got to be one of the reasons kombucha is so resistant to invading bacteria and historical longevity of kombucha tea (possibly thousands of years).
In one way or the other, you need to provide free oxygen access to the kombucha tea. But free access can only mean ‘free access to the surface of the tea’. But what about the volume of the liquid? Only way the oxygen transport can happen to the kombucha tea is THROUGH the surface area of the liquid. Because of that a kombucha brewing vessel should have relatively large surface area compared to the volume of the tea.
Common advice given for the kombucha container shape is that tea level at the container should be about as high as the diameter of the vessel. That may be good advice if we all use kombucha tea brewing jars about ‘few liters’ in volume. But what about much larger brewing vessels?
It so happens, that the advice (‘as high as wide’) is, although practical, actually totally fallacious. It is based on a very understandable logical mistake that similar shapes have constant volume-to-surface-area ratio regardless of the actual size of the shapes. That is not true at all. That is why smaller animals have relatively much higher heat loss than large ones. That is why chemical reactions are faster when the reactants are grinder fine — the smaller the particles, the bigger their surface area-to-volume ratio is. And that’s why larger brewing containers have less effective surface area relative to their volume!
There is one more thing to aware of in the quest of providing ample supply of oxygen to our kombucha ferments. How do fish breathe? One could make a joke that ‘like kombucha bacteria in brewing vessel’.
But the point is, that fish use oxygen dissolved in water for the breathing. Just like kombucha. I you ever had aquarium fish, then you know that providing enough oxygen to the water is essential. Regardless of your brewing vessel shape and other conditions, there’s always some oxygen dissolved in the water you use to make the kombucha tea. That is actually PRIMARY oxygen source for your kombucha tea. Oxygen contained in air is for replenishing only! Fresh kombucha tea should already have plenty of water-solved oxygen present at the start of the brewing.
What can we do to make sure there’s plenty oxygen in the combucha tea right from the start?
First, we should make sure that we don’t lessen the oxygen content already present. When making the tea for kombucha brewing, one should not boil the water for extended times. Boiling effectively removes oxygen (and other gases) from the liquid. There’s no reason to boil water for long time — actually it is not necessary to boil it at all — near boiling temperatures are just as good for making the tea and desinfecting the water.
We talked about possible contaminants in the water that will be the basis for kombucha tea. Contaminants needn’t be only chemical substances, they can be of biological origin — either in the form of unwanted bacteria or perhaps unwanted substances created by them. Boiling the water for kombucha tea brewing gives you another safeguard for achieving a healthy kombucha drink. Well, don’t boil, heating the water to near-boiling is enough. There’s still more you can to to saturate the fresh tea with oxygen.
Making the Tea
There are two ways to go about it. First is to simply brew the tea. Heat the water to boiling or near-boiling, add the tea, wait for a while and you’re done. Problem is, that you now have (maybe several liters) scalding-hot tea. You can’t pour it into your ferment! Doing so wold most likely kill all your kombucha if the temperature of the whole patch rises over 35 degrees. You need to cool down the tea before pouring it in with your starter tea. You will most likely place the steaming pot somewhere and leave it to cool. It takes time. The cooler the liquid already is, the more time it takes.
Cooling from 100 degrees to 70 degrees may take relatively short time, but cooling from 50 to 30 takes much longer. Sidenote from physics: cooling speed depends on the difference of temperatures (indeed, you are reading the Kombucha Science page!). While your cooling tea is hotter than 60–70 degrees, it is safe from unwanted bacteria (too hot), but anything under that, and those bacteria may start their new “home” while you wait for tea to cool sufficiently for kombucha. Just cover the pot with the cloth while it is still pretty hot and the tea should be safe.
Still, it may be kind of boring to wait while the pot cools because your kombucha activity for the day is still kind of unfinished. You can force-cool the pot instead. Just place it into the sink and let the cool water running. Cool water from the tap will effectively cool your “pot o’ tea” in a reasonable time and you don’t have to wait for too long.
There is still a simpler way — you don’t have to make the whole pot-full of tea — you can make only quarter pot full, for example. Of course, you need to add exactly the same amount of sugar and tea like you would use for the full pot. Simply put, you are making a tea concentrate. If the concentrate is ready, you can fill the pot with cold water from the taps. If you get the proportions right (boiling tea vs tap water) you can achieve suitable temperature tea right away. Right concentrate-to-water ratio depends on how cold water you get from your tap. 1/4 to 1/6 should be a good starting point.
If you decide to make the kombucha tea from the tea concentrate which you will dilute and cool with the cold water, you should consider two things. As you are adding unheated water, you are increasing the oxygen potential of your tea, because most of the liquid did not get heated. Adding cool water is actually your chance to maximize the oxygen content of the tea. You can do it by maximizing running water contact with air. Instead of using kitchen tap to add cold water to your kombucha tea concentrate, you can use the shower head. If it is convenient to you (you should not travel trough you house, up and down the stairs, with a pot of boiling tea) then shower head is a great way to saturate the water with oxygen.
Well, there you go, you insta-cooled the tea, boiled only a small amount of water for tea, heating was faster and you saved some electricity AND you saturated main volume of the tea with oxygen. It is all fine but there’s one critical problem with this method — large part of the water used was NOT sterilized. That may be a problem, or it may not. Only you can make a right decision about potential danger about using unpasteurized water for kombucha (or any other ferment) because only you know about quality of your water.
Even if your water is clean enough to use as is, something may change and you wouldn’t know about it. Maybe you forgot to change the water filter in your house for quite some time and there where exceptionally hot weather and something started to grow there.. Something that may not be a health risk to you but that ‘Something’ would love to thrive in a sugar solution with all the necessary substances that all bacteria would love — in your kombucha tea. Kombucha isn’t actually too easily contaminated because of its acidic nature, but the decision is yours. Points to note:
Boiling all the water
+disinfects the tea
-heating takes more time
-cooling takes more time
-uses more electricity
-long cooling time makes airborne contamination possible
-boiling removes oxygen
Boiling small part of the water
+heating is quick
+proper temperature after mixing with cold water
+cooling water can be saturated with oxygen
-unboiled water is a contamination risk
Kombucha Tea Recipe
That’s got to be the easiest part of the kombucha tea making. Simplest recipe would be: just brew the tea to your liking (with sugar, of course).
But we want to be more detail-oriented here in Kombucha Science anyway. Besides, almost all kombucha-related pages give a detailed recipe, so why shouldn’t we. Kombucha tea recipe main questions are: how much tea, how much sugar and how long to boil the tea.
Amount of tea is usually quoted as 2–5 grams to the liter of water. Sugar content should be about 50–100 g/l. 50 g/l is probably reasonable minimum while upper level can be much over 100 g/l. I’m sure you wouldn’t like the kombucha tea brewed with over 100 g/l sugar — too sweet. Boiling time is a slight controversy though. Some kombucha drinkers have reported boiling the tea for 20 minutes or more. Is there a good reason for extended boiling?
In my opinion, no. Kombucha is a historical staple for Russians. In Russia (and some eastern regions) there’s a strange way to use tea as some sort of high-causing drug. It basically works like that: one brews extra strong tea for extra long — for an hour, for example. The concentrate is suitable for diluting to a normal drinking tea, but sometimes is used in a concentrated form. That kind of caffeine overdose (yes, tea is a source of caffeine) sure makes one’s head spin. And, of course, that general-use tea concentrate was surely for replenishing a kombucha-making jar too.
As we don’t try to get ourselves high from the concentrated tea, there’s no reason to try to do the same with our kombucha ‘miracle mushroom’ drink. Besides, boiling tea for too long makes it bitter. Just brew as long as you normally would. One thing to note with the kombucha recipes is that they don’t have to be at all exact. You do have to use some appropriate routine though because doing it ‘by the eye’ is not good enough. I mean, can you reliably pour 400 grams of sugar to the bowl, for example? You may pour 600 (relatively unimportant difference) or 200 grams (twice the difference).
Using some sort of kitchen scales will be good enough and you don’t have to be punctual with your weighting procedure. Scales will just confirm that you are in an acceptable ballpark. For my kombucha tea recipe I tend to use relatively little sugar. If you intend to drink a lot of kombucha tea (as much as you drink sodas, or even more) then you will want to limit your sugar intake as much as possible. I’m sure the tea itself is an extremely positive food item, so you need not to skimp too much with the tea. Besides, kombucha culture would be happy with the fair amount of tea content in the brew. But it really isn’t critical. I used to brew long time with 2 grams to the liter of tea, but increased the concentration to 4 g/l for taste reasons only.
Then there is the matter of caffeine, when you choose the proper strength of the tea for the kombucha. And again, only you can make a good judgment for yourself. I don’t mind the caffeine in tea at all — take it from somebody who likes the coffee extremely mild.
Kombucha Tea Recipe:
Sugar — 60 g/l
Tea — 4 g/l
Simple, isn’t it? Well that’s the recipe for the tea suitable for kombucha brewing. It is only one of many possibilities though! Kombucha is happy with much wider variety of substance values than you are. That’s why you need to alter the recipe to suit yourself. But above is a good starting point.
Well, you brewed the tea, but something seems to be missing. You need the kombucha starter tea also! And you NEED it. You can’t brew the kombucha without it! There has been some user-initiative in the form of interest, that maybe kombucha culture can be started “from the scratch”. Question is basically — can the kombucha culture be started with other means than with historical kombucha starter tea?
My opinion is that it will be difficult. And if somebody manages to start a kombucha from the zero, would it really be kombucha? One great thing about starting to make kombucha in your home is that you can start it from a bacterial culture that is possibly thousands of years old! Think about it. Kombucha has been passed from hand to hand all this time. And all this time the ferment has been “learning” to live with us. Dogs too have been formed by time and conditions to be suited to live with us. You can’t just breed the dog from wild wolves — it takes long time. So, trying to start the kombucha culture from the scratch would be something like with dogs and wolves — you may achieve something but the wolves will be wolves and you just cannot mimic a thousand year of bacteria strain selection process in any reasonable time frame.
You just need to get the culture from somebody.
You have now learned about many of aspects that are related to the safe brewing of the kombucha tea, and you managed to get some starter tea (or kombucha scoby). Kombucha starter tea is nothing more than well-fermented kombucha tea. It is filled with bacteria and yeast and is fairly acidic. Importance of maintaining kombucha brew acidity was explained above.
You made the tea for kombucha and you have the starter tea ready, but the one question remains: how much fresh tea to the starter tea? Common suggestion is that the starter tea volume should be at least 10% of the new brew volume. I really want to be more conservative here. You don’t want to dilute the starter tea too much! If the acidity of the ferment ferment drops too low (too little starter tea and too much fresh tea) then you have created a dangerous situation for the kombucha and for yourself. Acidity of the kombucha tea is the only effective safeguard against harmful bacteria! Don’t dilute the starter tea too much! What if your starter tea is not very acidic? And you diluted it little too much? It’s a recipe for disaster, so be careful.
For my own kombucha brewing I have made a rule to use the ratio of 50% for the starter tea and fresh tea. Your batches will brew quicker and you maintain safe acidity all the time. With the last unknown out of the way, we can write the kombucha tea recipe again:
Sugar — 60 g/l
Tea — 4 g/l
Starter tea to fresh tea ratio 1:1
Note that if you have only kombucha scoby to start the new batch, much less fresh tea should be added. Kombucha scoby is not essential part of the kombucha and is a form of waste-product. As such, it is a worse material for starting a new kombucha brew because it contains less bacteria and other substances than equal volume of starter tea! That’s kind of obvious if you think that large part of the scoby material is simply cellulose! That’s why you should always prefer kombucha starter tea to the scoby for starting your own brewing. Of course, kombucha is started from the scobys all the time. It is partly because of the misunderstanding, that the ‘tea mushroom’ is a thing by itself. That misunderstanding is reaffirmed by many kombucha sites and the fact that those sites sell the scobys. I don’t want to step on anybodies toes and freely concede that the scoby myth IS a simple misunderstanding, and that the scoby is a good way to spread the kombucha, because the bacteria-impregnated cellulose blob (bacterial mat) is easy to transport (easier than the starter tea liquid).
You should not dilute the starter tea too much!
Batch Brewing vs Continuous Brewing
Batch brewing and continuous brewing are two main methods for brewing kombucha. They are quite different, at least at the first glance. Batch brewing is the method many are using. It goes something like that: “mix ’em all up and wait”. Wisecracks aside, that’s what it basically is. You prepare the new batch — make the fresh tea, mix it with starter tea and wait for the kombucha to ferment to your preferred level. When the batch is ready, one starts to consume it. That actually takes some time as you wont be drinking it all up at once. You will consume it during several days, maybe a week. For all that time, the kombucha will continue to ferment. That may not be a problem — maybe you started to drink it when it was kind of mellow tasting and ended the patch when it was already quite strong. Every day your kombucha tasted little bit different and “new”.
Problem is, when you drink a patch for a week and the patch should ferment at least 10 days, there will be some time when you wait for the next patch to brew and have nothing to drink (at least nothing as healthy as kombucha!). That means that you need to have several different patches going on all the time, several 3-liter jars, for example. Preparing the new patches all the time can become annoying and time consuming. Messing with jars, pouring stuff in and out, cleaning the jars etc.
If you want to be serious kombucha drinker, you need to make your life easier in the kombucha front. Actually, question isn’t about how easy is to maintain several jars of kombucha making from week-to-week. The fact of reality is, that if it isn’t almost trouble-free, then you won’t do it for any respectably long time-slice. You may keep it up for six months, but then you kind of drift away from kombucha brewing and find yourself a new recreational occupation. That may not be a bad thing at all, but kombucha is so fantastic food item that you really should stick with it for a long time.
Kombucha making got to be simpler than messing with the jars all the time. Besides, batch brewing has a vital drawback too. Brewing conditions vary greatly during the brew: especially sugar content and acidity. Batch brewing really is kind of a one-time act for your precious kombucha bacterial culture. But kombucha, like all living things, would like to have it’s living space more to be more stabile.
At the start of the new batch there’s maximum sugar content but minimal acidity in the liquid. Those are the ideal conditions for invading (and potentially harmful) bacteria. On the other hand, when the brew is at its full force, then there’s not enough sugar to feed on. But low acidity got to be the single most worrying aspect of the batch brew. Even if you follow our suggestion at the Kombucha Science and use as much starter tea as fresh tea, one could still do better. If we use the continuous brew method, we tackle those problems at once: we don’t need the array of different jars any more, cut out the maintenance greatly and maintain high acidity of the kombucha at all times!
Batch brewing is still useful when making all sorts of kombucha brewing tests, like trying different kinds of teas.
Continuous brewing is the only good way for high output relatively care-free kombucha brewing at home. Continuous brewing means that you have a relatively large volume of kombucha brewing all the time. Whatever the amount of ready-to-drink kombucha that gets to be taken out from the main brew is substituted with a fresh tea. Continuous brewing is excellent solution for those that are serious about kombucha drinking. And a large volume of kombucha is needed if there’s more than one person drinking it daily.
If you have two adults and some kids in your family who all drink kombucha, the amount consumed in a week can be respectable indeed. In case of continuous brewing, all kombucha tea is in a one large vessel. When you take your two or three day volume out from there, it is still a relatively small quantity relative to the whole volume of the currently brewing kombucha tea in a continuous brew vessel.
You should replenish what you take out from there. For example, a family that consumes 14 liters kombucha in a week (not unreasonable amount at all — couple of adults an few kids worth of daily dose times seven) takes out 4 liters every other day. The same amount of fresh tea should go back into the brewing vessel. But the 4 liters of fresh tea is small quantity compared to the quantity that must be in the continuous brewing vessel that is able to produce 14 liters of kombucha tea in a week! It must be much larger than 4 liters, that’s for sure. And that is the beauty of the contentious brewing: you have big stock fermenting all the time and anything that you pour in there isn’t going to change the state of the whole brew much at all. Acidity can drop only a little and the sugar content stays more stable also. Basically, kombucha bacteria have much more stable environment in a continuous brewing vessel than in a patch brewing one. And stable environment is whats all living things need to be happy and successful. In that sense, continuous brewing is ideal solution for the kombucha — and is a good solution for the brewer also!
All you need for the successful continuous brewing of the kombucha tea is a suitable, proper size brewing vessel. Question is, how big?
That depend on many things, like how big is the daily consumption, and how sour you like your kombucha. These things are easier answered by your own observations.
If you start brewing kombucha you probably use the batch brewing method. At first, you have so little kombucha that you really cannot afford to drink any of it. So be patient and grow your stock. Later you start to drink it and find your own preferences regarding to drinking volume and sourness of the drink. Then you will have a good idea of the speed of the process in relation to the consumption. Brewing temperature is surely a important variable here. I live in a cool climate and a would expect my kombucha to grow much quicker if I would live in a place where average brewing temperature would be 5 degrees higher, for example. You will find your optimal brewing parameters yourself, in time. We only try to give some general suggestions, because the question about proper brewing vessel size for the continuous brewing still stands.
Kombucha people usually give the fermenting time as 10 to 14 days. That is for the batch brewing. I’m sure the time actually varies quite a lot (because of the brewing temperature and for the taste preferences) but we take it simply as an arbitrary starting point. We actually need that batch brewing completion time estimate for getting right the continuous brewing parameters. We also take the brewing temperature to be around 22–23 degrees. Well, if you like your kombucha sour then 22 degrees and 12 days would be a good starting point. Note that for very small batches this may be way too long, as small batches tend to brew quickly — probably from easily available oxygen from the air (liquids in smaller jars have relatively more surface area than in larger ones, see above).
So, lets examine a scenario of a family that drinks 14 liters of kombucha in a week. I know that this amount may look absurdly large for those of us that treat kombucha tea strictly as a healthy tonic that are to be “sipped” in milliliter quantities. But we treat the kombucha here at the Kombucha Sciense more like a soft drink, and drinking volumes accordingly. 14 liters in a week is two liters in a day. If kombucha is to be brewed for 12 days in a batch brewing, then every two liters of fresh tea you pour in a continuous brewing vessel should ferment there for 12 days effectively. In 12 days you have removed 12 * 2 = 24 liters of kombucha tea from the brewing vessel (and added the same amount of fresh tea). So, the kombucha continuous brewing vessel should be at least 24 liters in our example. The formula for finding the continuous brewing vessel volume:
V = R * t
R — rate of consumption as volume-per-day
t — batch brewing time for your preferred kombucha taste in days. Note that brewing temperature is already factored into this parameter!
Also note that units are note important here, they may be gallons or liters or whatever.
This formula is a starting point only! Use it just like that — a rough starting point. With this formula you can at least find out approximate size for the continuous brewing vessel. We can learn from the formula that our above mentioned scenario needs a vessel at least 28 liters in size.
The formula is approximate at best, real results depend on your own kombucha continuous brewing routine. For example, you may take out the ready-to-drink kombucha daily, but refill the brewing vessel in every other or even third day. That sort of patterns (while completely viable in practice as the may be convenient from the maintenance standpoint) make the the formula possibly more inaccurate — but it doesn’t matter — the formula only gives a very rough starting point by default! Go with the formula and over dimension the result by 30% — eg, if the formula gives you a volume of 30 liters, get a vessel of 40 liters. Who knows, your consumption may go up and you would need bigger vessel anyway. Last is an example of ‘human factor’ — that’s why one should always take the accuracy of any empirical formulas with the very big grain of salt.
Kombucha continuous brewing is quite different from a patch brewing because it is a mixture of tea at very different fermenting stages. Small amount of the tea is practically fresh in the vessel, while small amount is very mature. Most of the tea is brewed at your chosen ‘batch brewing time’ (t in the above formula).
In batch brewing vessel all tea is at the same brewing stage, but continuous brewing vessel contains kombucha of very wide maturity stages. This got to create some interesting compounds in the brewing process. Kombucha people argue, that some of he healthiest substances can only be created by continuous brewing environment. Just for the record — some harmful stuff can also emerge from the extended brewing environment of the continuous brew.
Overall, the continuous brewing of kombucha got to be the best way to make that healthy ‘mushroom drink’. Maybe (just maybe) the optimal kombucha sourness level for continuous brewing can be slightly lower than is optimal for batch brewing, because the continuous brewing kombucha inherently contains long-brewed components anyway. As you shorten the brewing “cycle” (more frequent refills compared to the whole volume of the ferment) you lessen the probability of certain very long-lived brewing components that may be harmful — just be sure that the acidity of the continuous brew doesn’t drop too much, because that will be a real danger to your kombucha and to yourself!
How Long to Brew the Kombucha Tea
We have now tackled most technical aspects of kombucha making. What is left, is to argue about taste. Just kidding. But taste is an important aspect of the kombucha brewing process. We make the kombucha for drinking, right? So, what is the goal, what is good-tasting kombucha?
When the new kombucha batch starts, it tastes mostly like tea. Well, it is tea! Of course, starter tea colors the taste but it still very much like normal tea. When the fermenting goes on, the taste begins to change. Mostly, it goes more sour. Different kinds of acids are manufactured in the kombucha making process by the good bacteria of the ferment. One notable component of the kombucha tea is acetic acid. Apple cider vinegar consist mostly of acetic acid. Actually much the same process is used for vinegar making as it is for kombucha making. But kombucha tea creates much more varied acid palette than the vinegar making process. If vinegar would be our goal when brewing kombucha, it would be simpler just to buy apple cider vinegar from the store and use this in some acceptable way. But the vinegar is NOT what we want from kombucha! We want the other acids!
There is a point in the kombucha brewing process, where the acidity of the ferment will rise quickly. That is the time when substantially more acetic acid is produced. All other acid content will continue to increase but acetic acid content will increase even faster. That is the point that you as a kombucha maker must learn to recognize. From that point on kombucha acidity increases mostly from acetic acid. As we don’t particularly like to drink a diluted vinegar solution then we must make our kombucha making work in a way that kombucha is consumed in a proper fermentation stage.
Basically, we need to learn, when our healthy kombucha starts to change into kombucha vinegar. It is completely okay to let it go to vinegar for your starter tea backup reserves. Very vinegary kombucha makes the best starter tea! For drinking, however, we need to limit the brewing time in case of batch brewing, or choose proper replenishing cycle for continuous brewing.
One good indicator for the fact that the kombucha is ready to drink is that it changes to slightly clearer — the liquid starts to be transparent. That is a sign of increased acid content of the brew. Same thing happens when we squeeze some lemon juice to the ordinary tea — added acidity will clear the tea up somewhat.
Some kombucha enthusiasts use PH-strips to find the acidity of the ferment. It looks like a overkill, though, because your best instrument for measuring the maturity level of your kombucha ferment is You! Human taste buds and nose are actually a sophisticated chemical sensors, why mess with PH-strips?
It is true, that human senses are notoriously bad for finding absolute values of the physical stimuli. That is why you cannot place the acidity value of the solution by taste alone with any reasonable accuracy, and in that sense PH-strips may seem like a good choice for evaluating the state of the kombucha tea making. But we are very sensitive to taste coloration and can tell when the vinegary taste starts to power through, and therefore correctly detect when the kombucha is ready to drink.
Points to note:
- Kombucha is best just before the vinegar content starts to rise quickly
- PH-strips can be used to accurately measure the acidity of the kombucha
- when the kombucha gets clearer it probably starts to get ready
- trust your taste buds to assess the situation
Kombucha Health Effects
One of the more attractive reasons for kombucha drinking is the alleged health benefits. Kombucha, like many ancient food items and herbs, is believed to cure the array of different health problems. We don’t go so far here in Kombucha Science as to sign to it all. Just for the record, Kombucha Science doesn’t claim the kombucha tea to have any health-restoring properties. If you have a medical condition, you should see your physician!
We can still speculate about kombucha benefits to health (and please note that it really isn’t nothing more than a speculation). Kombucha is believed to have very powerful health-increasing effect. In fact, a lot of the kombucha websites boldly describe the health benefits of the kombucha and present detailed lists of specific health conditions that kombucha tea is supposed to remedy. Those lists include health problems starting from slight trouble with indigestion to the most serious of conditions, including cancer. It quite saddens me to read about “kombucha health benefits” at those sites — so many unproved claims, and so much irresponsible (false) hope to the ones that really have some serious health troubles. Such claims are result of irresponsibility.
I don’t say that kombucha doesn’t have any health benefits — I actually believe that it has, but to claim that kombucha cures this-or-that is misleading at best. If you are ill, it’s too late to start drinking kombucha, you should seek professional help instead. Sure, kombucha can be a great help in some medical conditions but we just can’t go on claiming a general medical usefulness when it has been useful in certain particular cases. All people are different and all medical cases are different. If other kombucha pages present kombucha as a miracle cure, so be it — we just don’t go that far here.
But we do believe in Kombucha Sciense that kombucha tea is a healthy drink for healthy persons. Kombucha is not a miracle cure — it is a health-food that is part of healthy living. Keep your mind clear and your body fit and you can’t go wrong with kombucha tea!
There is one mechanism that would explain kombucha great claimed health benefit list. There’s is actually one single aspect of human health that, when in peak condition, will help to avoid literally thousands of health problems — and that is the immune system. Immune system is basically our main protection mechanism against different diseases and health problems. Strong immune system is requirement for strong health!
Everything we can do to boost our immune system is in a very real sense beneficial to our health. And that’s where the kombucha tea steps in again. It is possible (but it is only a speculation!) that kombucha tea may be beneficial to the health of ones immune system.
There is an hypothesis how kombucha (or any other probiotic) can boost the immune system. Kombucha and other probiotics are beneficial to us, because they “rob” the living space from harmful bacteria in humans digestive system. Kombucha tea benefits to the digestive system is not in doubt. But how can kombucha strengthen ones immune system?
According to a (very speculative) hypothesis, kombucha and other probiotics do not do any good at all for the human organism. An that’s the point — they do nothing at all (and certainly no harm either). But they are foreign organisms to our body, and our body treats them as such. Our immune system reacts to them as a potential threat even if they actually are not. This keeps or immune system under some stress.
Believe or not, our modern cleanliness may create a condition where our immune system is underused — and that can lead to some serious health problems. Basically, kombucha and many other probiotics keep our immune system alert and fit, so that when a real threat emerges, it can give an effective response. That’s why it really makes great sense to consume probiotics and, of course, kombucha tea.
Kombucha is a Healthy Alternative to the Sodas
I find it quite strange that most of the kombucha pages treat the kombucha purely as a food item, but at the same time it should kind of consumed as a “miracle drink” — in small doses. Well, if one goes by the suggestions given in such pages, one has no other option. Kombucha is presented like a kind of a health-gimmick. Please don’t fall into the trap of thinking that ‘few ounces’ of kombucha tea in a day is gonna make you perfectly healthy, young, beautiful, etc.
If you actually want to drink kombucha, you got to think bolder. Even for one person normal consumption, much larger quantities are needed — much larger than those beautiful clear class jars you see presented in most kombucha sites (here too). For practical drinking quantities you need a brewing vessel tens of litters of volume. That way you actually can drink some of the kombucha you are making. Remember, brewing kombucha takes time and patience. That’s why you need a relatively large patch of kombucha going all the time — else you can drink only small quantity of it daily for the process to be balanced all the time.
If you take kombucha as a gimmick, you play with it for a couple of weeks, then you have a couple of liters of kombucha tea and, indeed, you can drink it all up. But there goes your starter tea stock, and you are left with nothing to make new kombucha from. It takes time to work up your kombucha volume to the amount that can give you sufficient daily supply.
If you start with 100 ml of starter tea, then after two weeks you’ll have 200 milliliters, then after two weeks you have doubled the quantity again, and so on. If you start with 100 ml, then it takes about seven weeks to have a stock of 13 liters of kombucha tea! And you can’t drink any of it during that time!
To be able actually drink the kombucha daily takes great patience at first. It takes scientific mind and skill to plan the setup for your effective kombucha making process. But the rewards are great! By training some patience and using your skill to set up a workable kombucha making routine, you don’t get a ‘miracle drink’ you sip ‘few ounces’ while you meditate — you get an extremely tasty and healthy alternative to sodas. That’s right, you can drink all the kombucha you want if you don’t treat it like the gimmick it isn’t, but as a centuries old healthy beverage! It IS tasty! And if you manage to fight temptation to use too much sugar (Kombucha Science recommended 60 g/l is perfectly reasonable amount), it really has no real drawbacks.
One thing to note is that if you have problem with over-acidity in your stomach, you may want to be careful with the kombucha. In any case, you should not drink too acidic kombucha because over-acidity poses a danger even to a healthy person. You don’t want your kombucha to be too low in acidity also, for the reasons mentioned above.
- Make the kombucha quite acidic but not too much
- Don’t use too much sugar
If you follow those simple suggestions you can completely give up sodas and drink as much kombucha as you like because in our modern times kombucha must be considered an essential part of the health-conscious living.