No Fizz

First it's nice to know that the amount of carbonation in KT has virtually no effect on the efficacy of the ferment. I say virtually because the impact is minor and arguments can be made both pro and con as to the effects of carbonation. And I might add that the presence of fizz in no way indicates whether the fermentation proceeded properly. If you're getting good SCOBY thickness but no fizz, this is actually a good thing since you have enough yeast to keep the bacteria happy and not enough to overwhelm them.

That said, what is reasonable to expect from a "normal" KT ferment? After 3 or 4 cycles of fermentation it is customary for KT to reward you with some bubbles. It can happen on the first cycle but this is entirely dependent on how the culture you received was generated, the handling prior to you receiving it as well as how you handle it.

A "balanced" ferment - and you'll hear me use that term a lot, will produce a fair amount of bubbles which will be evident when you pour it into a container and it produces some foam, similar to what washes up in the ocean on a windy day. In extreme cases it will come out like beer but that is unusual and may indicate an overabundance of yeast. Normally the bubbles will be barely noticeable by the palate when sipped directly from fresh ferment but it will have a quality that is much different from flat KT and much more desirable to the palate.

Often new users will experience flat KT initially because the yeast population hasn't enough variety or it hasn't hit that critical number to produce good fizz. They will eventually show up after successive brews, some are airborne others may be reluctant to reproduce due to being in a state of dormancy. There are a few things you can do in the mean time to help inspire them.

Different types of yeast produce more CO2. Too much sugar can decrease the amount of CO2. Weak tea will reduce the amount of carbonation. The type of tea can impact carbonation and temperature will affect carbonation.

Yeast normally shifts from CO2 production to alcohol production under two conditions. The first is lack of surface and dissolved oxygen the second is an overabundance of glucose. Therefore wire whipping or other forms of aeration prior to setting up a ferment or using a little less sugar can help increase carbonation in the early phases of fermentation.

Once the yeast fully populate, adding a little more sugar will get them going. You can do this half way through the fermentation cycle or just prior to bottling. Be conservative if you do it during bottling because you need only a tiny bit to create a grenade! I recommend a quarter of a teaspoon per quart. Some people add a couple of raisins or slices of ginger to a ten ounce bottle both of which work well.

If your brews are still sweet when you take them off let them go a little longer until they're real tart. You may find after a few extra days you will see a few tiny bubbles begin to show and rise to the surface. Use a flashlight and look very carefully. If you spot even one or two you're ready to bottle.

For world-class carbonation you need to bottle at room temp for 2 to 5 days prior to refrigeration. See the section on Two Stage Bottling for best results. Keep in mind if you store KT in a container that is not air tight it will eventually go flat just like any beer or soda would.

When you make your next batch use starter from the bottom of the last fermented batch. It will have more yeast. Use at least 20% starter until the fizz begins to show up better, and then you can back down to 10%. Also allow your starter to sit open at room temperature for 3 or more days (cover it with a sheer cloth, panty hose or paper towel.) This ensures activity is high and allows airborne yeast a chance to take residence.

If you've been using all black tea, try some different varieties. Green, in general, is superior for carbonation but you may want to mix it with black for a better taste. I recommend a 3 to 2 ratio of green to black for best results.

Get the temperature up to about 82 degrees if you can until the yeast get a strong hold and fizz begins to show up. Then drop it back down to 72-75 degrees thereafter to make sure the balance of the ferment doesn't tip to too much to the yeast. This can be a much bigger problem and take time to remedy. Some experts consider 73.5 degrees the optimum for culture balance and my own experience seems to prove that out. I like the improvement in flavor the lower temperatures bring but you will often sacrifice carbonation at lower temperatures.

Too Much Fizz

Too much carbonation is usually accompanied by premature souring, malformed SCOBYs and low concentrations of gluconic acid. Most beginners usually want to know how to increase carbonation rather than reduce it. But with successive brews often the yeast will become over stimulated, especially in the warmer months. Normally as a result of how KT is prepared, the yeast tends to go into fermentation early and begin producing alcohol along with relatively small amounts of CO2. But in the warmer months the likelihood of yeast being in respiration increases.

In respiration the yeast produce 3 times as much CO2 as in fermentation and no alcohol. They also burn oxygen and glucose at a higher rate. As a result the bacteria don't get the alcohol they use for fuel and to make matters worse they must compete harder for the available oxygen and glucose.

Now without alcohol, bacteria must rely solely on glucose and air to reproduce. But with the yeast in respiration this makes oxygen scarcer. As a result of this, the acetobacter reliance on surface air to produce cellulose and gluconic acid increases. Since CO2 is being generated at a higher rate it tends to pool on the surface and crowd out the oxygen. So the SCOBY may begin to form but, with it harder to locate surface oxygen, growth slows to a crawl.

So what can you do to decrease CO2:

 1. Increase the available glucose
 2. Decrease the strength of the tea
 3. Reduce the temperature
 4. Reduce the yeast population

The first two of these are a little less obvious and they also tend to oppose each other. This is because reducing tea reduces the nutrients yeast need to manufacture the enzymes, which cleave the sugar into glucose and fructose. So this can actually reduce the available glucose. However reducing the tea still tends to work because the yeast become less likely to respire and instead use the energy for producing alcohol which is what we want.

If you reduce the tea's strength it's even better to add some glucose directly in place of a portion of the sugar. This will ensure the yeast enter into what the brewing industry refers to as the "Crabtree effect" where fermentation replaces respiration prematurely. Karo or corn syrup are good sources of glucose, the latter being preferred.

Keep the temperature around or below 73F degrees (23C) . You can still get good ferments at 65F degrees (18C) but it can take a week or more longer to produce than at 73F degrees (23C).

To dramatically reduce the yeast populations see the section below titled "Increasing the Ratio of Acetobacter to Yeast Populations".

CLOUDY

The typical thing that causes KT to be cloudy is rapid yeast reproduction. Typically an abundance of CO2 accompanies this effect. The yeast aren't dead or fat enough to sink to the bottom and so they stay in suspension. If you want to clarify the liquid the best thing to do is use the two stage bottling technique I've listed below with one modification. Add just a touch of plain gelatin powder to the first stage of bottling. By the time you enter 2nd stage bottling the liquid will be perfectly clear.

However, even if you don't add gelatin, usually bottled KT will clarify with age so after a few weeks the yeast will just form sediment on the bottom of the bottles. 2 stage bottling with gelatin gives you a chance to remove most of the sediment prior to long term storage.

But beware! By reducing the cloudiness you also weaken the taste. A flavorful alternative I use is a slice of ginger root which will also boost the CO2.

SLIMY

A fellow brewer's KT often comes out slimy/syrupy where as mine is always clear and light.  I've come to the conclusion it may be due to the chemicals in their city water.  (I use straight well water.)

Be sure you boil the water for 10 minutes or more. This will give many chemicals like chlorine a chance to evaporate. Then when you transfer the water leave any heavy silt in the bottom of the pan you boiled in. Of course a good water filter couldn't hurt either.

If you still get slime then it could be the yeast and you may need to choke them out a little. Use extra sour starter; stuff that's fermented about 3 weeks or more and wash your culture in distilled vinegar before using it again.

This assumes you're using the standard 1 cup of sugar per 3 quarts of water. If you're using more than that then don't. In any case, it can't hurt you and most of the slime will precipitate out after it sits in the fridge for a week.

TOO SLOW

Here are some of the things that can put the culture into slow motion (in order of likelihood) :

1. Low temperatures
2. Too much sugar (or glucose)
3. Culture and/or starter refrigerated before setting up the ferment
4. Too little starter
5. Insufficient access to air
6. Overworked dieing culture
7. Cooked culture from introduction too early into warm tea
8. A contaminant
9. Tea type might have an additive that inhibits culture

If you detect the SCOBY is still growing then the last 5 items are unlikely. In most cases the bacteria are more susceptible to these last items than the yeast. But if you see continued growth, then it's a good indication everything is OK.

THIN SCOBY

Cool Temperatures, low yeast count, dormant bacteria, over stimulated yeast, impurities, types of tea and seasonal fluctuations can all cause thin SCOBYs. So first let's review the basics then we'll look at a technique that can revive a weakened culture.

Keep in mind seasonal changes will change the response of the culture. I have found early fall and early spring the best time for hearty delicious ferments. Of course this depends on where you live but after a few years of brewing you come to anticipate the effects. The best way to ensure you get healthy SCOBY growth is to keep the mother and starter active. Keep the cultures stored at room temperature in ample starter and covered in the usual manner with a breathable material.

Don't wash your fermenting vessel with antibacterial soap. Guess why? That thing that floats on top is made by bacteria and it only takes a bare trace of residual soap to kill the entire culture. If you're a clean freak make sure you rinse well.

If a thin SCOBY is accompanied by a sweet ferment, chances are you haven't brewed long enough. Let it go a couple more days and until the taste is tart. Also with this situation if your temperature is less than 70F degrees (21C) try to get it up a few more degrees to about 73F (23C). As a rule, avoid artificial stimulation because it tends to spoil the taste. Patience is the preferred approach to any kind of heating device.

If a thin SCOBY is accompanied by a sour ferment you have a weak bacteria culture and that will take a few cycles to correct. To find out how, see the section below titled "Decreasing the Ratio of Yeast to Acetobacter Populations."

HOLEY SCOBY

If your SCOBY gets holes but still comes out thick, that's great. It means you have ample yeast and bacteria growth along with lots of CO2. Nothing could be finer. If the SCOBY looks weak then you need to swing the "balance" to the bacteria side. See the section below on "Increasing the Ratio of Yeast to Acetobacter Populations."

LUMPY SCOBY

This is one of those rare things that happen once in a blue moon. The SCOBY develops an almost uniform lumpy surface that looks like someone laid a wet handkerchief over a bunch of marbles. I've never seen it happen in successive brews and I'm not sure what causes it.

I read something once by one of the renowned KT researchers that this maybe an effect caused by certain tannins that cause the cells to clump. Don't know. . . but I do know it's nothing to worry about and chances are you may never see the effect a second time. If you do, try a different brand of tea.

NO SCOBY

Not much you can do in this situation. There has to be at least some surface formation to recover. If there isn't then you need to get a new culture and starter from someone. To avoid facing this sort of thing in future follow these precautions:

 1. Don't use antibacterial soap to clean the fermenting vessel
 2. Don't add a culture to hot or even warm tea. The tea should be below body temperature
 3. Don't add any herbs, spices or anything else foreign unless it's known to be safe for Kombucha
 4. Keep the fermenting vessel away from any disturbing fumes such as paint or solvents
 5. Use only pure Kombucha for starter
 6. Make sure you add sugar, not Stevia or any other artificial sweetener

You can gradually kill a Kombucha culture over successive ferments with ginger, cinnamon and other herbs or household spices. These sorts of things should only be added when you're ready to bottle. Never allow them in your starter.

If you see at least the beginning of a clear film on the surface then refer to the section below titled "Decreasing the Ratio of Yeast to Acetobacter Populations."

DARK SCOBY

The longer you ferment with the same SCOBY the darker it will get. This is because both the tea and the yeast make it a little darker each cycle. It's fine to keep using the same culture as long as it seems to be making good brews but if the culture begins to shed dark dried looking layers it's probably time to retire it.

Personally, I prefer to use the healthiest looking culture with each brew. Regardless of how many cycles they've been through I pick the whitest, densest culture I have on hand. This ensures my bacteria are always getting the strongest start possible. Maintaining the culture's balance over successive brews dictates we give the bacteria as much advantage as possible.

SCOBY SINKS

This is normal. Some SCOBYs are denser than others depending on how much CO2 is trapped between the layers. Often a sinker will make some of the best brews.

SCOBY CLIMBS OUT OF POT

OK the SCOBY isn't really trying to escape but sometimes it can seem that way. This is a sign that there is plenty of yeast activity. Often the SCOBY creates an air-tight seal on the mouth of the container. When this happens and the yeast produce more CO2 than can stay dissolved in the ferment, then the gas starts to push the SCOBY up and eventually lifts it out of the container.

If the culture suspends itself over the liquid due to trapped gas, it's a good idea to push it down gently and remove the gas pocket so that the newly formed SCOBY is in contact with the liquid. Otherwise the bacteria stop doing their job, which means less acids and more alcohol.

TOO SOUR OR TASTES LIKE VINEGAR

The longer a brew ferments the closer it will get to vinegar. Occasionally though it will ambush you by souring faster than expected. If the SCOBY is fat and healthy you probably waited a little too long. Higher temperatures tend to accelerate fermentation and can catch you off guard. Three degrees over the period of a week can shorten the ferment cycle a full day. Many people who live in warmer climates routinely brew in 5-7 day cycles instead of the 10 days typical for a 72 to 75F degree range.

However, if a brew sours prematurely, before the SCOBY has a chance to get to about 3/8" (1 cm) in thickness, then you have a culture that is becoming unbalanced and the yeast need to be put in check. This is actually pretty common, especially in warmer temperatures. My guess is since the yeast can reproduce with or without surface air they have a slight advantage over the bacteria that rely on air for reproduction.

To swing the balance back in favor of the bacteria see the section below "Decreasing the Ratio of Yeast to Acetobacter Populations."

TOO SWEET

As long as you're seeing SCOBY growth allow the fermentation to proceed. This could be due to low temperatures or a semi-dormant yeast population. I've had brews that took up to 3 weeks before they started to get tart. This can work to your advantage because slower brews have a greater likelihood of forming many of the beneficial acids that make KT so healthy for us. Not only that but you'll find the slower a ferment proceeds the rounder and more delicious it turns out.

NAIL POLISH REMOVER

Occasionally a brew will smell nasty like some kind of solvent or nail polish remover. This is more likely than not due to the formation of aldehyde by foreign bacteria. You might notice clouding of the liquid when this occurs. It's best to dump the liquid when this occurs and wash the culture well. Unfortunately, since this type of bacteria does well in acidic conditions, there is no guarantee you can get rid of them with successive brews. Try soaking the culture in pure distilled vinegar over night before you use it to make another batch. If the next batch turns out the same, you may want to think about replacing the culture.

ROTTEN CITRUS SMELL

Sometimes you may encounter a skunky smell a bit like rotten orange. This often coincides with brewing at higher temperatures. Besides temperature, you might notice this effect is greater the longer it takes for the vessel to seal itself. Until the surface seals off completely (with a new SCOBY) the door is left open for a greater degree of respiration.

During a brew cycle there are two types of activities going on; one is fermentation (anaerobic) and the other respiration (aerobic). When the yeast are very active there is a higher level of respiration going on. Respiration is a complex process that produces a lot of intermediate compounds, one of these being citric acid.

Though not desirable tasting this is nothing to be alarmed about. Once the respiration abates, these compounds tend to reconfigure and dissipate. Storing without air, where respiration is impossible, often eliminates this taste after a few weeks.

MOLD

A lot of new comers mistake a forming discolored SCOBY for mold. It's pretty rare to get mold if you're using good starter. So first of all make sure it's mold. As soon as you see a sign, look very closely to see if the surface is fuzzy. If not then let the ferment continue and keep checking for signs of fuzz. If you don't see fuzz, then it's not mold.

Mold is probably the most dangerous threat to KT. This is because all mold is not the same and depending on the variety that establishes itself, it can leave the KT poisonous not to mention unpalatable. I am less fearful than most but will still tell you it's a whole lot faster and safer to get a new culture from someone than it is to recover from a moldy culture.

However for the fool hardy, let me tell you how I recovered from mold. Since mold always grows on the surface of a Kombucha culture and the SCOBY is usually pretty buoyant it makes it easier to isolate and remove.

First throw out the ferment that had the mold. It's useless and too dangerous to consume. If you have another culture throw out the one with mold and start over. Otherwise take the moldy culture and carefully remove all parts suspected of mold without touching the mold. You want to be careful not to accidentally contaminate yourself or your working area.

It's all right if you radically carve up the culture because all you need is a small piece to regenerate a new culture. In fact you might want to carve the culture up into a couple of pieces to run parallel regeneration batches. Take the uncontaminated pieces and submerse them in pure distilled vinegar for a couple of days.

Now you are ready to make a new batch. Make your next batch as usual but use 10% distilled, or pre-boiled vinegar instead of starter. If the next batch forms mold (which it won't, trust me) follow the above procedure again. If no mold develops you can make the following batch as normal using starter instead of vinegar. Don't bother drinking any of the recovery batches. They won't taste good and they may still have trace contamination. But before you make the next batch meant for consumption a few sage words about avoiding mold in the future:

Sanitary conditions are not the answer! At least not practically speaking. More often than not, mold spores are airborne all around us. The question becomes what can one do to increase resistance to mold when fermenting KT.

The only way to protect yourself is by raising the acidity level of the ferment when it is first prepared. This is the number one reason why we add starter. Mold deplores acidity.

Well, many people add starter and still get mold - Why? Some people ferment a much shorter time than others because they prefer the ferment on the sweeter side. As a result the acidity level is lower. This means they increase the likelihood that mold will form before the fermentation acidifies to a level which rejects mold.

Always use 10-15% starter or about half as much vinegar. If you're already using starter there are 3 possible ways to further avoid mold:

 1. Add a few tablespoons of distilled, pre-boiled, vinegar gently to the top of the brewing vessel once it's ready to ferment
 2. Use more starter
 3. Use more acidic starter

This last one I prefer. I do this by using the ferment I store my cultures in for starter. It's usually very close to vinegar. I can use less since it's much stronger. I just replace what I use with fresh ferment so I maintain a constant level and turnover.

DEALING WITH CHLORINE

I use well water and after I chlorinated my well it took almost 6 months before my KT started tasting good again. So anything you can do to reduce the effects of chlorine is well worth it. Some water purification systems will help remove chlorine but one thing that always helps is boiling the liquid uncovered for 10 to 15 minutes. Be sure to put on extra water since you will probably loose 10 to 20% during boiling.

Remember KT is half bacteria and most things we do to protect ourselves from bacteria, such as water treatment, sun bathing and antibacterial cleaners are poison to KT. So you want a bacteria friendly environment. This is not as bad as it sounds because Kombucha is extremely good at segregation and when prepared properly will take care of ensuring only acid loving friendly bacteria take residence during fermentation.

DEALING WITH CONTAMINATED WELL WATER

If your well is contaminated you need a good filtration system which is designed to remove those specific contaminants.

Please permit me that hypocritical moment. Personally, I have decided to live with my well that is both contaminated with bacteria as well as chemicals from the abuse of farmers with their pesticides and nitrogen based chemicals. My rationale - good or bad is, that whatever they put in the ground I've already consumed from the vegetables they grow since I've been eating them my whole life.

As far as bacteria, the best tasting KT I ever made was from this contaminated water before I had the water tested and treated. Now I just boil the water for 10 minutes and the KT tastes pretty good, but maybe not quite as good as before. What can I say, our variety of bacteria tasted pretty good. Actually this is testimony to the power of Kombucha to reject most foreign bacteria. If it can live in KT chances are it won't hurt you and you may already have some of these organisms living inside you.

BREWING IN HIGH TEMPERATURES

It's nearly impossible to make good KT at high temperatures. Bacteria start to die above 95F degrees (35C) whereas the yeast will survive to about 120F degrees (49C). So the hotter it is the more likely you're making tea wine. Not only that, but once the static ambient temperature goes above 82F degrees (28C) the yeast are usually so active that they out pace the bacteria and cause the ferment to sour well before the most beneficial compounds are created by the bacteria.

However, there are three things you can do to help keep the balance of the culture at higher temperatures:

 1. Use the densest, whitest SCOBY you have
 2. Use the oldest, sourest starter available (or pure distilled vinegar)
 3. Use a vessel with greater surface area

We use the densest, whitest SCOBY because it contains the least yeast. If you have a choice, use the newest available.

Using the oldest, sourest starter available ensures most of the yeast will have died off or the distilled vinegar option will have no live yeast. This causes the yeast to get off to an extremely slow start and allows the bacteria more opportunity to do their job. It may take your ferment twice as long but the results are much better for you and tastier as well. Of course if you're in a hotter climate that may offset much of the delay.

Finally, using a vessel with greater surface area allows a large bacteria population to develop faster in the presence of air and further help maintain the culture's balance.

From everything the experts tell us, no matter what the temperature, the majority of the acids, which are really good for us don't accumulate for at least a week. So do everything you can to slow the pace down by dropping the temperature or reducing the yeast populations.

BREWING IN LOW TEMPERATURES

You need at least 64F degrees (18C) for a viable balanced culture. Below that the bacteria tend to go to sleep and the yeast will be pretty sluggish and produce nothing but alcohol. However, to a degree the bacteria can adjust and if you see the SCOBY growing that's a good sign that the bacteria have enough energy to build their cellulose homes. The only thing you need is plenty of patience because at colder temperatures it could take 4 or 5 weeks to ferment properly.

Avoid artificial heating because for a good ferment you should have evenly distributed heat. However, if you must heat, do it gently and direct it at the surface where the bacteria collect. But avoid direct lighting, especially sunlight.

BREWING IN ERRATIC TEMPERATURES

Occasionally I have heard from people who must deal with wide temperature swings. Typically in arid climates, temperatures will swing radically between day and night. Sometimes this will result in a home temperature swinging as much as 10 degrees. Swings where the mean temperature is fairly close to our target temperature are not a real concern. They may influence the taste somewhat but they will not negatively affect the culture. In cases where the mean temperature itself is well below or above the target temperature, you can mitigate the impact to a large degree using the suggestions in the sections Brewing in Low (or High) Temperatures. Warming is easy enough to do using a 25 Watt bulb suspended about 10 inches above the ferment vessel, but cooling is a bit tricker. You can try using a thermo cooling blanket or if you want to go ancient school, check Google or Wikipedia for "zeer pot" which is a power-free possibility.

SEASONAL EFFECTS

Seasonal effects can be dramatic. I have found that although summer in general produces the fastest ferments, the best tasting ferments happen in the early fall and early spring. Just ride it out and do your best to maintain the balance of the culture. By taking steps to maintain balance you can neutralize most of the impact that different seasons bring.

GREEN VERSUS BLACK TEAS

In general green teas tend to out perform black tea. They make a fatter SCOBY, a better mix of beneficial acids and they help produce larger amounts of carbonation. However, green teas tend to sour faster and produce an astringent quality that many people don't like. For this reason I use a 3 to 2 mix of green to black. I find the taste a perfect marriage and the results consistently good.

Tea drinkers have told me that it's best to use steep times half as long for green, as you would black. If the temperature is near boiling, 5 minutes for green and 10 for black is adequate. Some prefer much longer. I'm not sure there is a significant advantage by going longer unless you want to use less tea to reduce the caffeine content. I find the taste better with shorter steep times but if you tend to bottle the ferment and store for more than a week you'd be hard pressed to tell the difference by then.

BREWING VESSELS AND SURFACE AREA

Surface area doesn't have that great an impact until you get to the outer extremes. Too little surface area and you might as well be making beer. Too much surface and you loose large amounts of liquid to evaporation and SCOBY growth. However, in general, the more surface area, the faster fermenting can proceed without sacrificing the quality of the beverage.

Keep in mind larger surface areas will sour faster. In general, a one to one ratio of diameter to liquid depth will produce adequate results and tends to be a nice compromise as far as controlling the consistency of the beverage.

DECREASING THE RATIO OF YEAST TO ACETOBACTER POPULATIONS

The bacteria rely on the yeast for alcohol and glucose. Beyond this they need oxygen and trace amounts of nutrients that they can get from the air and tea. So it stands to reason by supplying alcohol and glucose we can reduce their reliance on the yeast while we take measures to impede the yeast. Also, although the yeast can withstand much wider extremes in temperature, we can still pick the optimum band for the bacteria where the yeast tends to be more sluggish. This range tends to be in the 65 to 75F degrees (18 to 24C) range.

First it's always nice to start with a strong dense SCOBY. You can raise one through a simple procedure that gradually starves the culture to the point where the bacteria have a propagation advantage over the yeast. I like to think I'm grooming a master race of bacteria but its actually more about stalling yeast reproduction.

Start with a portion of newly fermented tea and place it in your standard size fermenting container or maybe a little smaller so that you have at least four inches of liquid depth. Allow fermentation to continue for a few more weeks. At this point the second formed SCOBY is likely a great mother candidate but if it still looks brownish, you can opt to repeat the process.

If you do decide to repeat the process then remove the newly produced SCOBY and filter the fermet contents with a paper towel. Alternatively you can syphon off the top clear portion of the liquid which is preferred but not critical, because at this point the yeast have mostly died off or have gone dormant. Rinse and wipe clean the container. Then replace the filtered/syphoned liquid back into the container and continue to ferment for several more weeks, until the culture gets to approximately 1/2" (> 1 cm) in thickness.

Now you're ready to begin fermenting with the new master race. However, to ensure the balance remains stable or slightly towards the bacteria side follow these procedures during your normal brew preparations:

1. Use more acidic starter.
   I do this by using the ferment I store my cultures in for starter. It's usually very close to vinegar. I can use less since it's much stronger. I just replace what I use with fresh ferment so I maintain a constant level and turnover. If you just created the master race as instructed above, the left over solution is ideal to use for starter. Use less though because it will be extremely acidic.
    
2. Keep the temperature below 75F degrees (24C). Optimum temperature is 73F degrees (23.5C) for an already balanced culture.
    
3. Use starter that is taken off the top of any standing ferment to ensure you pull from where the bacteria to yeast ratio is the highest.
    
4. Squeeze the juice of any new cultures you won't be saving into the new ferment or where you store your starter.
    
5. Use weak rather than strong tea strength.
   Strong tea provides more sterols that the yeast needs to reproduce. If they don't get these compounds from the tea they must manufacture them their selves and this will slow them down ensuring the bacteria remain more dominant. Assuming a 10 minute steep for black and 5 minutes for green you should be using no more than 3 regular sized tea bags per quart of tea. If you steep longer use less.
    
6. Use Green tea or a 3:2 ratio of green to black tea. Green slightly favors the bacteria, this a recommendation, not required.
    
7. If available, add glucose (or dextrose).
   You can use clear Karo as an imperfect but acceptable source or corn syrup, which I much prefer. If you add glucose keep the ratio about 1 to 7 of glucose to sugar. Keep in mind you only need a little to jump start the bacteria because once the yeast work on the sugar for a day or two there will be an abundance of glucose manufactured typically right up to the 9th day of fermentation. It is worth noting that using too much glucose can potentially stall a ferment.

INCREASING THE RATIO OF YEAST TO ACETOBACTER POPULATIONS

It's rare that a brewer needs to increase yeast activity because the yeast naturally dominate over time and as KT brewers, keeping them in check is the path to the most healthy and best tasting KT. But if you ever do find yourself in this position, here are some things that you can do:

1. Use more black tea, i.e. make stronger tea and prefer black.
    
2. Pull starter from the bottom of the previous brewed ferment and use plenty of it.
    
3. Be conservative on sugar. It's best to start out with a little less sugar and then add more after the ferment has proceeded a few days. This is because once the yeasts break down the sugar into glucose, if too much is in solution the yeast can become sluggish and reproduce more slowly. Home brewers commonly know this as the "Crabtree Effect".
    
4. Keep the temperature between 75 and 85F degrees (24 to 30C).
    
5. For those who like to experiment, use the "Continuous Fermentation" technique. This is where you keep a larger container constantly fermenting by replacing the portion you drink with fresh sweetened tea. You'll need a special container with a spout at the bottom so you don't overly disturb the surface when drawing off some to drink. Always draw off prior to replacing tea to insure you get the best quality beverage.

INCREASING CARBONATION

Although some types of yeast tend to produce more alcohol than others (and subsequently less CO2), carbonation is more so a product of the activity of the culture. CO2 production continues throughout the fermentation as yeasts go through growth and reproduction.

Typically more CO2 is produced by yeast prior to reproduction and when the greatest amount of oxygen is available. But an active culture will have yeast at various stages. Also the presence of oxygen becomes less of a factor when there is a dearth of available glucose.

That said the best ways to increase carbonation are as follows:

1. Use the 2-stage bottling technique outlined below. In a nut shell, the object is to fill bottles to the top with no air gap, seal securely and let them sit at room temp for 2 - 5 days at which point it's time to refrigerate. This helps increase carbonation without sacrificing the balance of the culture. The rest of the techniques also play toward increasing the yeast population so use these techniques only when 2-Stage Bottling fails to produce the desired results.
    
2. When you make your next batch use starter from the bottom of the last fermented batch. It will have more yeast. Use at least 20% starter until the fizz begins to show up better, and then you can back down to 10%. Also allow your starter to sit open at room temperature for a few days. This insures activity is high and allows airborne yeast a chance to take residence.
    
3. Use a little more tea. Some compounds (sterols?) which the tea provides, help the yeast work faster otherwise the yeast must take a time out to manufacture them theirselves.
    
4. Get the temperature up to about 82F degrees (28C) if you can until the yeast get a strong hold and fizz begins to show up. Then drop it back down to 72-75F degrees (22-24C) thereafter to make sure the balance of the ferment doesn't tip to too much to the yeast. This can be a much bigger problem and take time to remedy. Optionally bottling with a little added sugar, ginger, raisins or other dried fruit does wonders both for taste variations and pumping up the carbonation.

TWO STAGE BOTTLING TECHNIQUE

I currently use a two stage bottling technique to finish off my KT fermentation. This method is fairly easy and allows for tweaking the end product along the way to adjust for variation in the fermentation results. In stage one, plastic bottles are used to store the ferment to allow carbonation to build up, typically over a couple of days following harvest of the ferment. In stage two, I use glass bottles with plastic lids, which is how I store KT until I'm ready to drink it.

Any size bottles can be used. I prefer 2 liter plastic and 10 oz. glass soda bottles. The 10 oz. are ideal portions for storage and the 2 liter plastic are easy to handle avoiding breakage. There is not quite a 7 to 1 ratio when tranfering but I have been using the space to either add ginger root or to top off the neck of each 10 oz. bottle with sour cherry juice.

Here is the procedure:

1. Coarse filter the ferment. I say coarse because you really don't want to remove everything, just the "ooglies". Some yeast residue has to pass through in order to make carbonation. I prefer a paper towel but pantyhose or linen is just as good.
   
   It's best if the ferment is filtered in one pass for consistent results. However, I typically filter while I fill three 2 liter bottles in sequence since I brew a couple of gallons. Typically after the bottles age, each bottle will be more carbonated than the previously filled, due to more yeast collecting toward the bottom of the ferment during the transfer. To help compensate for this, I now fill the bottles about 3/4 first and then reverse the order to finish filling the bottles. There is still some slight variation in carbonation but I can compensate for this by the timing of when I move the bottles to cold storage.
    
2. After the KT has been filtered, fill the plastic bottles to the rim leaving as little space as possible for air. When capping, you can gently squeeze the bottle to remove excess air leaving the bottle just slightly soft when capped.
    
3. Store the bottles at room temperature and check each day by squeezing the bottle to note the pressure. A good brew should make the bottles hard (like a basket ball), in a few days. I have had batches take almost a week when the yeast are less active.
    
4. Once the bottles have built up pressure you should refrigerate them for a couple of days to let the yeast go dormant and allow the gas to reduce pressure. This makes it easier to transfer to the glass bottles.
    
5. After the bottles have chilled a few days, transfer the contents to glass bottles. When pouring, gently pour off the liquid trying to keep the silty yeast residue in the bottom of the plastic bottle for later discard (it's job is done.)
   
   Take careful note of the rim of the glass bottles as you fill them. When carbonation is plentiful, it will want to foam as you pour. This is your clue to slow down since you don't want to pour so fast that you can't properly top off each bottle during the transfer.
   
   Try not to leave space for air. You can always top off the last little gap with anything handy - KT, juice, etc. The small amount shouldn't really matter. Whereas, the less air is trapped, the more stable the brew over time.

TIPS

I don't like plastic for long-term storage - the taste isn't the same after a few weeks. When I open a plastic bottle for transfer and find it has no bubbles I make ginger ale KT by adding a couple of ginger root slices to the glass bottle during transfer. The ginger will produce significantly more carbonation over time and help compensate for a flat brew. It also tastes great.

I rarely add ginger to a highly carbonated batch - some times it comes out too bubbly to enjoy. Or worse, it erupts when opening so you loose half! Making ginger ale KT is actually my favorite. However, don't use the ginger ale version for starter, it will kill the acetobacter.

Also when you open the first plastic bottle for transfer, this is a good time to taste test. If you find it too tart you can add a little fructose to sweeten. But be careful and quick about it because if the carbonation is high it will begin foaming as soon as you add the fructose. This is also a good time to add other flavorings besides ginger, such as banana, apple, vanilla, etc. Dried fruit is preferred over fresh since there is less chance of introducing a contaminant that will create off flavors.

REDUCING CAFFEINE

If you use one or more of the following suggestions you can reduce the caffeine content to 10-50% of a normal cup of hot tea. Here are things that help reduce caffeine using regular tea.

1. Green tea has almost half the caffeine content as black plus it only requires half the steep time, which means there's less time for caffeine to leach.
    
2. You can half the content again by cold steeping the tea. After you boil the water, let it cool and then put the tea bags in.
   
   Colleen, (Colleen Allen; The late beloved KT researcher and E-author), used to suggest leaving it in the fridge over night but chances are as long as it remains covered it should not spoil over the course of a day. At room temp 8-12 hours should do the trick. (Make sure you leave the sugar out during steeping.) To be extra safe you could even add some sour starter at this point to further protect against mold.
    
3. Instead of cold steeping another neat idea is to pre-steep the tea bags in boiled hot water for 30 seconds and then re-steep in fresh hot water. Most of the caffeine will be washed out in the pre-steep so you're left with decaf in the second steep.
    
4. Some tea experts or a little research on the net can tell you what varieties of tea are lower in caffeine.
    
5. Use less tea. It takes very little tea to make good KT. You can use 1/2 to 1/3 what is normal tea drinkers strength.

STARTING A STARTER POT

The "starter pot" technique holds the promise of continuous brewing but with the control of batches. If we think more like a biologist/farmer and develop the starter and SCOBY we need, then we ensure consistent high quality results. All it requires is another container about the same size as the ferment vessel used for batch brewing. If you haven’t got a starter pot, wait until you have a sour batch you think you missed the timing on and put it aside to use as a starter pot.

The starter pot is where we groom the culture. It is a continuously fermenting pot but with a twist, instead of adding sweet tea, we add already fermented Kombucha. This subtle difference turns out to be huge in terms of how the yeast and bacteria behave. When the initial fermentation has been set aside for use as a starter pot, the yeast has passed the point of reproduction. The air is cutoff by the SCOBY and the sugar has all been consumed or at least converted into glucose and fructose.

At this point the yeast will remain unmotivated unless sugar is reintroduced. Because the yeast are inactive, the bacteria have more access to residual glucose. As they do the pH of the reservoir drops lower than would normally occur because they make gluconic acid which is much more acidic. Eventually the acidity causes yeast to decay faster and as long as they aren’t reproducing, there are no replacements. This causes a burn-off of yeast, yet the acid loving bacteria remain active as long as there is glucose, alcohol and air.

Over time the starter pot becomes rich in bacteria and thin in yeast. This is the exact opposite of what normally happens in KT fermentation. If undisturbed, a very dense white SCOBY will grow on the surface of the starter pot. When it is used along with the aged starter, we have obtained maximum levels of bacteria and minimized the amount of yeast introduced to our next ferment.

Following this approach ensures consistent high quality KT. But beware, fermentation will take longer and stay sweeter. The sweet taste may fool you when a brew is bacteria rich, even though it’s ready. It is not unusual for fermentation to take almost twice as long and still stay sweet. The only clue will be in the pH level of the brew which will be much lower than previously experienced with either batch or CB brewing methods.

A final note on starter pots. Because decay happens faster you will need to filter it of dead cells regularly to avoid producing off tastes due to yeast cannibalization. Use a course filter like a paper towel which will allow bacteria to pass through and catch most of the yeast. How much sludge you find at the bottom will be your clue as to how often to do this. Typically, every 4 weeks is adequate.

DISCLAIMER

This website is the result of hundreds of experiments performed over several years, tracking and recording different KT formulas and techniques coupled with knowledge I gained from the beer and wine brewing experts along with the documented research of KT done by Guenther Frank, Mike Roussin, Norbert Hoffman and Philippe Blanc to name just a few.

In many cases I deduced culture behavior from the results observed collectively. Some of these conclusions may be suspect since I was ahead of common knowledge at the time I first wrote this (circa 2000). If there is anything in this document that contradicts known research you have possession of or can direct me to, I'd like to hear about it.

QUESTION NOT ANSWERED?

Do you have a question or seek a solution to a Kombucha problem not covered here? You can email me with the details of your situation including information about the water, temperature, type and size of brewing vessel or anything else suspected of contributing to the problem.

EMAIL:   Len Porzio