Kombucha Fixing

Obtaining and Maintaining the Maximum Taste & Benet from yourKombucha through Consideration & Application of Balance.

By Len Porzio

Those new to brewing Kombucha often have the same questions and problems withmaintaining consistency of the ferment. Quite often the rst couple of batches aregreat and then things slowly begin to go wrong with subsequent batches.This is because there are several varieties of yeast and bacteria involved in a verycomplex chain of biological and chemical events that all lend to the end product.When one or more elements begin to dwindle or dominate the characteristics of thebrew can change radically.This is both the good news and the bad, because slight variations in balance canachieve a large variety of tastes without substantial impact to the ecacy of the brew.However, once you know the indicators of which way the balance is shifting it's reallysimple to correct and maintain.Basically although there are several varieties of organisms in play, in general, theconditions tend to favour either the yeast or the bacteria. At the end of this documentare techniques used to enhance both. (Ref. Increasing the Ratio of Acetobacter toYeast Populations and, Increasing the Ratio of Yeast to Acetobacter Populations)Personally I have found the yeast are much more aggressive than the bacteria and thebalance tends to shift in time to the yeast. But occasionally you may need to go in theopposite direction. For example people often ask how to get more carbonation in theirferment. Increasing the yeast population will denitely help but there are better waysto achieve bubbly Kombucha without disturbing the balance. A section is alsoincluded in this document to do just that. (Ref. Increasing Carbonation)The following table of contents lays out the links in this document

No Fizz Thin SCOBYToo Sour

Tastes LikeVinegar

MoldBrewing in

hightemperatures

DecreasingYeast to

AcetobacterRatio

Kombucha, The Balancing Act http://users.bestweb.net/~om/kombucha_balance/

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Too Much Fizz Holey SCOBY Too Sweet Dealing withChlorineBrewing in LowTemperatures

IncreasingYeast to

AcetobacterRatio

Cloudy Lumpy SCOBY Nail PolishRemoverContaminated

Well Water HeatingIncreasing

Carbonation

Slimy No SCOBY Like RottenCitrusSeasonalEects

2 StageBottling

Technique

Too Slow Dark SCOBY Green vs BlackTeasBrewing

Vessels SurfaceArea

ReducingCaeine

SCOBY Sinks Starter PotClimbs Out of

PotDoublingTechnique

TERMS and their meanings - as used in these pages.SCOBY - (Symbiotic Culture of Bacteria and Yeast) - The descriptive term for the Kombucha Culture.ACETOBACTER - http://en.wikipedia.org/wiki/AcetobacterFERMENT - The Sweetened Tea during process of Fermentation and as brewed Kombucha Tea.

No Fizz First it's nice to know that the amount of carbonation in KT has virtually no eect on the ecacy of theferment. I say virtually because the impact is minor and arguments can be made both pro and con as tothe eects of carbonation. And I might add that the presence of zz in no way indicates whether thefermentation proceeded properly. If you're getting good SCOBY thickness but no zz, this is actually agood 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 fermentationit is customary for KT to reward you with some bubbles. It can happen on the rst cycle but this isentirely dependent on how the culture you received was generated, the handling prior to you receivingit 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 bubbleswhich will be evident when you pour it into a container and it produces some foam, similar to whatwashes up in the ocean on a windy day. In extreme cases it will come out like beer but that is unusualand may indicate an overabundance of yeast. Normally the bubbles will be barely noticeable by thepalate when sipped directly from fresh ferment but it will have a quality that is much dierent from atKT and much more desirable to the palate.


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Often new users will experience at KT initially because the yeast population hasn't enough variety or ithasn't hit that critical number to produce good zz. They will eventually show up after successivebrews, 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.Dierent types of yeast produce more CO2. Too much sugar can decrease the amount of CO2. Weak teawill reduce the amount of carbonation. The type of tea can impact carbonation and temperature willaect carbonation.Yeast normally shifts from CO2 production to alcohol production under two conditions. The rst is lackof surface and dissolved oxygen the second is an overabundance of glucose. Therefore wire whipping orother forms of aeration prior to setting up a ferment or using a little less sugar can help increasecarbonation 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 waythrough the fermentation cycle or just prior to bottling. Be conservative if you do it during bottlingbecause 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 o let them go a little longer until they're real tart. Youmay nd after a few extra days you will see a few tiny bubbles begin to show and rise to the surface.Use a ashlight 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 48 to 72 hours prior to refrigeration.See the section on Two Stage Bottling for best results. Keep in mind if you store KT in a container thatis not air tight it will eventually go at 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 havemore yeast. Use at least 20% starter until the zz begins to show up better, and then you can back downto 10%. Also allow your starter to sit open at room temperature for 3 or more days (cover it with a sheercloth, panty hose or paper towel.) This insures activity is high and allows airborne yeast a chance totake residence.If you've been using all black tea, try some dierent varieties. Green, in general, is superior forcarbonation but you may want to mix it with black for a better taste. I recommend a 3 to 2 ratio of greento black for best results.Get the temperature up to about 82 degrees if you can until the yeast get a strong hold and zz beginsto show up. Then drop it back down to 72-75 degrees thereafter to make sure the balance of the fermentdoesn't tip to too much to the yeast. This can be a much bigger problem and take time to remedy. Someexperts consider 73.5 degrees the optimum for culture balance and my own experience seems to provethat out. I like the improvement in avor the lower temperatures bring but you will often sacricecarbonation at lower temperatures.

Too Much FizzToo 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 carbonationrather than reduce it. But with successive brews often the yeast will become over stimulated, especiallyin the warmer months.Normally as a result of how KT is prepared, the yeast tends to go into fermentation early and beginproducing alcohol along with relatively small amounts of CO2. But in the warmer months the likelihoodof yeast being in respiration increases.


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In respiration the yeast produce 3 times as much CO2 as in fermentation and no alcohol. They also burnoxygen and glucose at a higher rate. As a result the bacteria don't get the alcohol they use for fuel andto 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 inrespiration this makes oxygen scarcer. As a result of this, the acetobacter reliance on surface air toproduce cellulose and gluconic acid increases. Since CO2 is being generated at a higher rate it tends topool on the surface and crowd out the oxygen. So the SCOBY may begin to form but, with it harder tolocate surface oxygen, growth slows to a crawl.So what can you do to decrease CO2:

Increase the available glucose1.Decrease the strength of the tea2.Reduce the temperature3.Reduce the yeast population4.

The rst two of these are a little less obvious and they also tend to oppose each other. This is becausereducing tea reduces the nutrients yeast need to manufacture the enzymes, which cleave the sugar intoglucose and fructose. So this can actually reduce the available glucose. However reducing the tea stilltends to work because the yeast become less likely to respire and instead use the energy for producingalcohol 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 thesugar. This will insure the yeast enter into what the brewing industry refers to as the "Crabtree eect"where fermentation replaces respiration prematurely. Karo or corn syrup are good sources of glucose,the latter being preferred.Keep the temperature around or below 22 degrees C (73F) . You can still get good ferments at 18degrees C (65F) but it can take a week or more longer to produce than at 22 degrees C (73F).To dramatically reduce the yeast populations see the section below titled "Increasing the Ratio ofAcetobacter to Yeast Populations".

CLOUDYThe typical thing that causes KT to be cloudy is rapid yeast reproduction. Typically an abundance ofCO2 accompanies this eect. The yeast aren't dead or fat enough to sink to the bottom and so they stayin suspension. If you want to clarify the liquid the best thing to do is use the two stage bottlingtechnique I've listed below with one modication. Add just a touch of plain gelatin powder to the rststage 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 theyeast will just form sediment on the bottom of the bottles. 2 stage bottling with gelatin gives you achance to remove most of the sediment prior to long term storage.But beware! By reducing the cloudiness you also weaken the taste.

SLIMY


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My brother's KT often comes out slimy/syrupy where as mine is always clear and light. I've come to theconclusion it may be due to the chemicals in his 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 chanceto evaporate. Then when you transfer the water leave any heavy silt in the bottom of the pan you boiledin. Of course a good water lter 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 extrasour starter; stu that's fermented about 3 weeks or more and wash your culture in distilled vinegarbefore using it again.This assumes you're using the standard 160 grams of sugar per 2 Litres of water. If you're using morethan that then don't. In any case, it can't hurt you and most of the slime will precipitate out after it sitsin 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) : Low temperatures.1.Too much sugar (or glucose).2.Culture and/or starter refrigerated before setting up the ferment.3.Too little starter.4.Insucient access to air.5.Overworked dieing culture.6.Cooked culture from introduction too early into warm tea.7.A contaminant.8.Tea type might have an additive that inhibits culture.9.

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

THIN SCOBYCool Temperatures, low yeast count, dormant bacteria, over stimulated yeast, impurities, types of tea

and seasonal uctuations can all cause thin SCOBYs. So rst let's review the basics then we'll look at atechnique that can revive a weakened culture.Keep in mind seasonal changes will change the response of the culture. I have found early fall and earlyspring the best time for hearty delicious ferments. Of course this depends on where you live but after afew years of brewing you come to anticipate the eects. The best way to insure you get healthy SCOBYgrowth is to keep the mother and starter active. Keep the cultures stored at room temperature in amplestarter and covered in the usual manner with a breathable material.


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Don't wash your fermenting vessel with antibacterial soap. Guess why? That thing that oats on top ismade by bacteria and it only takes a bare trace of residual soap to kill the entire culture. If you're aclean freak make sure you rinse well.If a thin SCOBY is accompanied by a sweet ferment, chances are you haven't brewed long enough. Letit go a couple more days and until the taste is tart. Also with this situation if your temperature is lessthan 21C degrees (70F) try to get it up a few more degrees to about 23C (74F). As a rule, avoidarticial stimulation because it tends to spoil the taste. Patience is the preferred approach to any kind ofheating device.If a thin SCOBY is accompanied by a sour ferment you have a weak bacteria culture and that will take afew cycles to correct. To nd out how, see the section below titled "Decreasing The Ratio of Yeast toAcetobacter Populations."

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

LUMPY SCOBYThis is one of those rare things that happen once in a blue moon. The SCOBY develops an almostuniform lumpy surface that looks like someone laid a wet handkerchief over a bunch of marbles. I'venever 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 eect caused bycertain tannins that cause the cells to clump. Don't know. . . but I do know it's nothing to worry aboutand chances are you may never see the eect a second time. If you do, try a dierent brand of tea.

NO SCOBYNot much you can do in this situation. There has to be at least some surface formation to recover. Ifyou see at least the beginning of a clear lm on the surface then refer to the section below titled"Increasing the Ratio of Acetobacter to Yeast Populations". If there isn't then you need to get a newculture 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.


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5) Use only pure Kombucha for starter.6) Make sure you add sugar, not Stevia or any other articial sweetener.You can gradually kill a Kombucha culture over successive ferments with ginger, cinnamon and otherherbs or household spices. These sorts of things should only be added when you're ready to bottle.Never allow them in your starter.

DARK SCOBYThe longer you ferment with the same SCOBY the darker it will get. This is because both the tea andthe yeast make it a little darker each cycle. It's ne to keep using the same culture as long as it seemsto be making good brews but if the culture begins to shed dark dried looking layers it's probably time toretire it.Personally, I prefer to use the healthiest looking culture with each brew. Regardless of how manycycles they've been through I pick the whitest, densest culture I have on hand. This ensures mybacteria are always getting the strongest start possible. Maintaining the culture's balance oversuccessive brews dictates we give the bacteria as much advantage as possible.

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

SCOBY CLIMBS OUT OF POTOK the SCOBY isn't really trying to escape but sometimes it can seem that way. This is a sign that thereis plenty of yeast activity. Often the SCOBY creates an air-tight seal on the mouth of the container. Whenthis happens and the yeast produce more CO2 than can stay dissolved in the ferment, then the gasstarts 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 gentlyand remove the gas pocket so that the newly formed SCOBY is in contact with the liquid. Otherwise thebacteria stop doing their job, which means less acids and more alcohol.

TOO SOUR OR TASTES LIKE VINEGAR


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The longer a brew ferments the closer it will get to vinegar. Occasionally though it will ambush you bysouring 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 o guard. Three degrees overthe period of a week can shorten the ferment cycle a full day. Many people who live in warmer climatesroutinely brew in 5-7 day cycles instead of the 10 days typical for a 22 to 24 Degrees C ( 72-75 F)degree range.However, if a brew sours prematurely, before the SCOBY has a chance to get to about 1 cm (3/8") inthickness, 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 canreproduce with or without surface air they have a slight advantage over the bacteria that rely on air forreproduction.To swing the balance back in favor of the bacteria see the section below "Decreasing The Ratio of Yeastto Acetobacter Populations."

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

NAIL POLISH REMOVEROccasionally a brew will smell nasty like some kind of solvent or nail polish remover. This is more likelythan not due to the formation of aldehyde by foreign bacteria. You might notice clouding of the liquidwhen 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 canget rid of them with successive brews. Try soaking the culture in pure distilled vinegar over nightbefore you use it to make another batch. If the next batch turns out the same, you may want to thinkabout replacing the culture.

ROTTEN CITRUS SMELLSometimes you may encounter a skunky smell a bit like rotten orange. This often coincides with brewingat higher temperatures. Besides temperature, you might notice this eect is greater the longer it takesfor the vessel to seal itself. Until the surface seals o completely (with a new SCOBY) the door is leftopen for a greater degree of respiration.During a brew cycle there are two types of activities going on; one is fermentation (anaerobic) and theother respiration (aerobic). When the yeast are very active there is a higher level of respiration goingon. Respiration is a complex process that produces a lot of intermediate compounds, one of these beingcitric acid.Though not desirable tasting this is nothing to be alarmed about. Once the respiration abates, thesecompounds tend to recongure and dissipate. Storing without air, where respiration is impossible, often


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eliminates this taste after a few weeks.

MOLDA lot of new comers mistake a forming discolored SCOBY for mould. It's pretty rare to get mould ifyou're using good starter. So rst of all make sure it's mould. As soon as you see a sign, look veryclosely to see if the surface is fuzzy. If not then let the ferment continue and keep checking for signs offuzz. If you don't see fuzz, then it's not mould.Mould is probably the most dangerous threat to KT. This because all mould is not the same anddepending on the variety that establishes itself, it can leave the KT poisonous not to mentionunpalatable. I am less fearful than most but will still tell you it's a whole lot faster and safer to get anew culture from someone than it is to recover from a mouldy culture.However for the fool hardy, let me tell you how I recovered from mold. Since mold always grows on thesurface of a Kombucha culture and the SCOBY is usually pretty buoyant it makes it easier to isolate andremove.First throw out the ferment that had the mould. It's useless and too dangerous to consume. If you haveanother culture throw out the one with mould and start over. Otherwise take the moldy culture andcarefully remove all parts suspected of mould without touching the mould. You want to be careful not toaccidentally 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 anew culture. In fact you might want to carve the culture up into a couple of pieces to run parallelregeneration batches. Take the uncontaminated pieces and submerse them in pure distilled vinegar fora couple of days.Now you are ready to make a new batch. Make your next batch as usual but use 10% distilled, orpre-boiled vinegar instead of starter. If the next batch forms mould (which it won't, trust me) follow theabove procedure again. If no mould develops you can make the following batch as normal using starterinstead of vinegar. Don't bother drinking any of the recovery batches. They won't taste good and theymay still have trace contamination. But before you make the next batch meant for consumption a fewsage words about avoiding mould in the future:Sanitary conditions are not the answer! At least not practically speaking. More often than not, mouldspores are airborne all around us. The question becomes what can one do to increase resistance tomould when fermenting KT.The only way to protect yourself is by raising the acidity level of the ferment when it is rst prepared. This is the number one reason why we add starter. Mould deplores acidity.Well, many people add starter and still get mould - Why? Some people ferment a much shorter timethan 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 mould will form before the fermentation acidies to a levelwhich rejects mould.Always use 10-15% starter or about half as much vinegar. If you're already using starter there are 3possible 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'sready to ferment.2) Use more starter.


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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 veryclose to vinegar. I can use less since it's much stronger. I just replace what I use with fresh ferment soI maintain a constant level and turnover.

DEALING WITH CHLORINEI use well water and after I chlorinated my well it took almost 6 months before my KT started tastinggood again. So anything you can do to reduce the eects of chlorine is well worth it. Some waterpurication systems will help remove chlorine but one thing that always helps is boiling the liquiduncovered 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 watertreatment, sun bathing and antibacterial cleaners are poison to KT. So you want a bacteria friendlyenvironment. This is not as bad as it sounds because Kombucha is extremely good at segregation andwhen prepared properly will take care of insuring only acid loving friendly bacteria take residenceduring fermentation.

DEALING WITH CONTAMINATED WELL WATERIf your well is contaminated you need a good ltration system which is designed to remove thosespecic contaminants.Please permit me that hypocritical moment. Personally, I have decided to live with my well that is bothcontaminated with bacteria as well as chemicals from the abuse of farmers with their pesticides andnitrogen based chemicals. My rationale - good or bad is, that whatever they put in the ground I'vealready 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 thewater tested and treated. Now I just boil the water for 10 minutes and the KT tastes pretty good, butmaybe not quite as good as before. What can I say, our variety of bacteria tasted pretty good. Actuallythis is testimony to the power of Kombucha to reject most foreign bacteria. If it can live in KT chancesare it won't hurt you and you may already have some of these organisms living inside you.

BREWING IN HIGH TEMPERATUREIt's nearly impossible to make good KT at high temperatures. Bacteria start to die above 35 Degrees C(95 F) whereas the yeast will survive to about 49 Degrees C (120 F). So the hotter it is the morelikely you're making tea wine. Not only that, but once the static ambient temperature goes above 28Degrees C ( 82 F) degrees the yeast are usually so active that they out pace the bacteria and cause theferment to sour well before the most benecial compounds are created by the bacteria.However, there are three things you can do to help keep the balance of the culture in highertemperatures. Always use the densest, whitest SCOBY you can nd because it will contain less yeast. Ifyou have a choice, use the youngest available.


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Next use the oldest, sourest starter available or use pure distilled vinegar. Most of the yeast will havedied o in old starter and none will exist in pure vinegar. This will cause the yeast to get o to anextremely slow start and allow the bacteria more opportunity to do their job. It may take your fermenttwice as long but the results are much better for you and tastier as well. Of course if you're in a hotterclimate that may oset much of the delay and result in your brew times being what the rest of usexperience, about 8-10 days. From everything the experts tell us, no matter what the temperature, themajority of the acids, which are really good for us don't accumulate for at least a week. So doeverything you can to slow the pace down by dropping the temperature or reducing the yeastpopulations.Finally, use a vessel with greater surface area. This will allow large bacteria populations to developfaster and further help maintain the culture's balance.

BREWING IN LOW TEMPERATURESYou need at least 18 Degrees C (64F) for a viable balanced culture. Below that the bacteria tend to goto sleep and the yeast will be pretty sluggish and produce nothing but alcohol. However, to a degreethe bacteria can adjust and if you see the SCOBY growing that's a good sign that the bacteria haveenough energy to build their cellulose homes. The only thing you need is plenty of patience because atcolder temperatures it could take 4 or 5 weeks to ferment properly.Avoid articial heating because for a good ferment you should have evenly distributed heat. However, ifyou must heat, do it gently and direct it at the surface where the bacteria collect. But avoid directlighting especially sunlight.

TIPS ON HEATING DURING FERMENTATIONAfter years of experimenting I take every opportunity I can to slow down Kombucha fermentation. Thisis because left to itself the yeast tend to dominate the process over time, producing largely acetic acid(vinegar). The faster you brew, the lower the gluconic acid levels as well as several other heavier acidswhich form later in the fermentation process. Since heating accelerates the process I avoid it as a rule.That said sometimes there is a need to warm the culture for a while. People who live with theirthermostats set below 65 (brrrr..) will nd fermentation takes forever. And occasionally a culture thathas been refrigerated for more than a few days, or has a very low yeast count, may need a little help toget the populations balanced and fully active again.In all cases heating should be gentle and kept below 86 degrees. Keep in mind a temperature between73 and 74 degrees has been proven the most eective for overall consistent KT quality. To stimulate theculture you want to gage how much higher the temperature should be by how much activity yourculture is experiencing.As a routine, heating above 80 degrees is bad for maintaining proper culture balance because it overstimulates the yeast which then compete too heavily with the bacteria for glucose. Heating above 90degrees will begin to kill the bacteria if done over an extended period. Over 100 degrees and you prettymuch guarantee only the yeast will survive if anything.Also, whether it is to compensate for a cold room or to stimulate a sluggish culture, heating for the rst24 to 48 hours has advantages over heating throughout the entire fermentation cycle. This is because ithelps the yeast produce glucose early on before they enter into full scale respiration and reproduction.This allows the bacteria nourishment with minimal competition from the yeast.


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If heating will be a habit due to storing the ferment at low temperatures then keep in mind the bacteriatend to collect at the surface where as the yeast will be dispersed throughout the solution. This means ifyou have an overall weak culture you might want to heat along the sides of the vessel. If over time yound the yeast are more active than the bacteria (indicated by souring without signicant SCOBYgrowth), switch heating to be directed at the surface where the bacteria collect.You can heat from the bottom also by using a pet warmer mat type of device. This is the least preferredmethod and should be reserved for very weak yeast populations (indicated by a ferment which soursslowly and produces very meager SCOBY growth.)Those of you who have normal temperatures to brew in but seek to stimulate the culture because itseems weak or slow should view heating as a short term measure. In fact, if heating gets the desiredresults for a batch it should be discontinued on future ferments. This is because once the culture gainsthe necessary strength to ferment and feed the bacteria then your populations have reached criticalmass and future eorts will most likely involve reigning in activity to maintain the culture's balance.Without robbing you of creative ideas on ways to heat your culture, here are the most popular methodsI've heard people use:

Suspend a 25 watt bulb about 1 ft above the surface.Wrap the vessel in an Electric blanket set on low.Use a pet warmer mat.

The rst can be done inside of a cabinet with an accompanying thermometer so you can properlymonitor the vessel's environment. The others are not as easy to monitor and control. For this reason Iwould limit their use to the rst few days of fermentation.

SEASONAL EFFECTSSeasonal eects can be dramatic. I have found that although summer in general produces the fastestferments, the best tasting ferments happen in the early fall and early spring. Just ride it out and do yourbest to maintain the balance of the culture. By taking steps to maintain balance you can neutralize mostof the impact that dierent seasons bring.

GREEN VERSUS BLACK TEASIn general green teas tend to out perform black tea. They make a fatter SCOBY, a better mix ofbenecial acids and they help produce larger amounts of carbonation. However, green teas tend to sourfaster and produce an astringent quality that many people don't like. For this reason I use a 3 to 2 mixof green to black. I nd 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. Ifthe temperature is near boiling, 5 minutes for green and 10 for black is adequate. Some prefer muchlonger. I'm not sure there is a signicant advantage by going longer unless you want to use less tea toreduce the caeine content. I nd the taste better with shorter steep times but if you tend to bottle theferment and store for more than a week you'd be hard pressed to tell the dierence by then.


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BREWING VESSELS AND SURFACE AREA Surface area doesn't have that great an impact until you get to the outer extremes. Too little surfacearea and you might as well be making beer. Too much surface and you loose large amounts of liquid toevaporation and SCOBY growth. However, in general, the more surface area, the faster fermenting canproceed without sacricing the quality of the beverage.Keep in mind larger surface areas will sour faster. In general, a one to one ratio of diameter to liquiddepth will produce adequate results and tends to be a nice compromise as far as controlling theconsistency of the beverage.

DECREASING THE RATIO OF YEAST TO ACETOBACTERPOPULATIONS

The bacteria rely on the yeast for alcohol and glucose. Beyond this they need oxygen and trace amountsof nutrients that they can get from the air and tea. So it stands to reason by supplying alcohol andglucose 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 optimumband for the bacteria where the yeast tends to be more sluggish. This range tends to be in the 18 to 24Degrees C (65 to 75F) range.But rst it's always nice to start with a strong dense SCOBY. You can raise one through a simpleprocedure that gradually starves the yeast and bacteria insuring only the strong survive. I like to thinkI'm grooming a master race of bacteria.The procedure is simple. Start with a portion of newly fermented tea and place it in your standard sizefermenting container or maybe a little smaller so that you have at least four inches of liquid depth. Allow fermentation to continue for 3 more weeks.At the end of three weeks discard the newly produced SCOBY and lter the contents with a paper towelor coee lter. If you can nd a way to syphon just the top clear portion of the liquid this is preferredbut it's not critical because at this point the yeast have mostly died o or gone dormant.Rinse and wipe clean the container. Then replace the ltered liquid back into the container andcontinue to ferment for another couple of weeks or until the culture gets to approximately a 12 cm(1/2") in thickness.Now you're ready to begin fermenting with the new master race. However, to insure the balanceremains stable or slightly towards the bacteria side follow these procedures during your normal brewpreparations:Use more acidic starter. I do this by using the ferment I store my cultures in for starter. It's usuallyvery close to vinegar. I can use less since it's much stronger. I just replace what I use with freshferment so I maintain a constant level and turnover. If you just created the master race as instructedabove, the left over solution is ideal to use for starter. Use less though because it will be extremelyacidic.Keep the temperature below 24 Degrees C (75F). Optimum temperature is 23 Degrees C (73.5F) for analready balanced culture.


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Use starter that is taken o the top of any standing ferment to insure you pull from where the bacteriato yeast ratio is the highest.Squeeze the juice of any new cultures you won't be saving into the new ferment or where you store yourstarter.Use weak rather than strong tea strength. Strong tea provides more sterols that the yeast needs toreproduce. If they don't get these compounds from the tea they must manufacture them their selvesand this will slow them down insuring the bacteria remain more dominant. Assuming a 10 minute steepfor black and 5 minutes for green you should be using no more than 3 regular sized tea bags per quartof tea. If you steep longer use less.Use Green tea or a 3 to 2 ratio of green to black tea.If available, add glucose. 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 mindyou only need a little to jump start the bacteria because once the yeast work on the sugar for a day ortwo there will be an abundance of glucose manufactured typically right up to the 9th day offermentation.

INCREASING THE RATIO OF YEAST TO ACETOBACTERPOPULATIONS

Use more black tea.Pull starter from the bottom of the previous brewed ferment and use plenty of it.Be conservative on sugar. It's best to start out with a little less sugar and then add more after theferment has proceeded a few days. This is because once the yeasts break down the sugar into glucose, iftoo much is in solution the yeast can become sluggish and reproduce more slowly. Home brewerscommonly know this as the "Crabtree Eect".Keep the temperature in the 24 to 30 Degrees C (75 to 85F) range.For those who like to experiment, use the "Continuous Fermentation" technique. This is where you keepa 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 whendrawing o some to drink. Always draw o prior to replacing tea to insure you get the best qualitybeverage.

INCREASING CARBONATIONAlthough 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 throughoutthe fermentation as yeasts go through growth and reproduction.Typically more CO2 is produced by individual yeast prior to reproduction and when the greatest amountof oxygen is available. But an active culture will have yeast at various stages. Also the presence of


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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 two stage bottling technique outlined below. In a nut shell, the object is to ll bottles to thetop with no air gap, seal securely and let them sit at room temp for 48 - 72 hours at which point it's timeto refrigerate. This helps increase carbonation without sacricing the balance of the culture. The restof the techniques also play toward increasing the yeast population so use these techniques only whenTwo 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 havemore yeast. Use at least 20% starter until the zz begins to show up better, and then you can backdown to 10%. Also allow your starter to sit open at room temperature for 3 or more days. This insuresactivity 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 fasterotherwise the yeast must take a time out to manufacture them their selves.4) Get the temperature up to about 28 Degrees C (82F) if you can until the yeast get a strong hold andzz begins to show up. Then drop it back down to 22 to 24 Degrees C (72-75 F) thereafter to make surethe balance of the ferment doesn't tip to too much to the yeast. This can be a much bigger problem andtake time to remedy. Optionally bottling with a little added sugar, ginger, raisins or other dried fruitdoes wonders both for taste variations and pumping up the carbonation.

TWO STAGE BOTTLING TECHNIQUE

I currently use a two stage bottling technique to nish o my KT fermentation. This method is fairlyeasy and allows for tweaking the end product along the way to adjust for variation in the fermentationresults.In stage one, plastic bottles are used to store the ferment to allow carbonation to build up, typically overa 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 600 ml plastic and 300 ml glass soda bottles. This way I have anexact 2 to 1 ratio when I transfer from plastic to glass. The 300 ml are ideal portions for storage and the600 ml plastic are easy to handle and they insure there is exactly the right amount for transfer - nothingwasted and no room for air.Here is the procedure:1. Coarse lter 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 towelbut pantyhose or linen is just as good.It's best if the ferment is ltered in one pass for consistent results. Since I brew a gallon, I've always


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ltered half at a time into a 2 Litre jug which is then used to decanter into individual 600 ml bottles.And guess what I found? After the bottles age, those from the rst half usually have little carbonationand the second half are like beer. This is due to more yeast collecting in the lter and being forcedthrough, the closer you get to the bottom of the ferment.Note: I still lter half at a time but now I do so on purpose. See my tips at the end of this procedure.2. After the KT has been ltered ll the plastic bottles to the rim leaving as little space as possible forair. When capping, gently squeeze the bottle to remove excess air leaving the bottle just slightly softwhen capped.3. Store the bottles at room temperature and check each day by squeezing the bottle to note thepressure. A good brew should make the bottles hard, (like a basket ball), in one to two days. I have hadbatches take almost a week when there wasn't enough active yeast.4. Once the bottles have built up pressure you should refrigerate them for a couple of days to let theyeast go dormant and allow the gas to reduce pressure. This makes it easier to transfer to the glassbottles.5. After the bottles have chilled a few days, transfer the contents to glass bottles. When pouring, gentlypour o the liquid trying to keep the silty yeast residue in the bottom of the plastic bottle for laterdiscard, (it's job is done.)Take careful note of the rim of the plastic bottle as you pour. Good carbonation should show bubblesforming around the rim as you pour. This is your clue since you don't want to pour so fast that you see itfoam when transferring.Try not to leave space for air. If you have to discard too much residue to ll a bottle, top it o withanything handy - KT, wine, beer, apple juice. It doesn't really matter unless you have to ll more than thelast couple of millimeters in the neck. However, the less air is trapped, the more stable the brew overtime.

TIPSI don't like plastic for long-term storage - the taste isn't the same after a few weeks. When I open aplastic bottle for transfer and nd it has no bubbles I make ginger ale KT by adding a couple of gingerroot slices to the glass bottle during transfer. The ginger will produce signicantly more carbonationover time and help compensate for a at brew. It also tastes great. I rarely add ginger to a highlycarbonated batch - some times it comes out too bubbly to enjoy. Or worse, it erupts when opening soyou loose half! Making ginger ale KT is actually my favorite. This is why I still lter half at a time. Almost invariably I end up with half ginger-ale, half straight KT when I'm done. However, don't use theginger ale version for starter, it will kill the acetobacter.Also when you open the rst plastic bottle for transfer, this is a good time to taste test. If you nd it tootart you can add a little fructose to sweeten. But be careful and quick about it because if thecarbonation is high it will begin foaming as soon as you add the fructose. This is also a good time to addother avorings besides ginger, such as banana, apple, vanilla, etc. Dried fruit is preferred over freshsince there is less chance of introducing a contaminant that will create o avors.

REDUCING CAFFEINE


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Here are things that help reduce caeine using regular tea.1. Green tea has almost half the caeine content as black plus it only requires half the steep time, whichmeans there's less time for caeine to leach.2. You can half the content again by cold steeping the tea. After you boil the water, let it cool and thenput the tea bags in. Colleen, (Colleen Allen; The late beloved KT researcher and E-author), used tosuggest leaving it in the fridge over night but chances are as long as it remains covered it should notspoil over the course of a day. At room temp 8-12 hours should do the trick. (Make sure you leave thesugar out during steeping.) To be extra safe you could even add some sour starter at this point tofurther protect against mold.3. Instead of cold steeping another neat idea is to pre-steep the tea bags in boiled hot water for 30seconds and then re-steep in fresh hot water. Most of the caeine will be washed out in the pre-steep soyou're left with decaf in the second steep.4. Some of the tea experts on this list or a little research on the net can tell you what varieties of tea arelower in caeine.5. Use less tea. It takes very little tea to make good KT. You can use 1/2 to 1/3 what is normal teadrinkers strength.If you use one or more of these suggestions you can reduce the caeine content to 5% or less of anormal cup of hot tea.

STARTER POTThough not required, a starter pot oers several advantages in helping to maintain a consistent productand healthy balanced culture. You may already have the beginnings of a starter pot if you are storingspare cultures in KT somewhere.Besides a place for storing spare cultures, starter pots provide the most acidic starter available forghting mold. They also ensure the bacteria remain fully active while keeping the yeast in check buthealthy.Though it may be counter intuitive, this dissolve-your-dentures, extremely acidic starter actuallyimproves the taste of KT when maintained properly.A starter pot should hold roughly 5 to 10 times the amount normally used for starter or half to an equalamount of the tea volume you currently brew with. This ensures the bulk of the starter uid is extremelyaged and acidic when drawn to begin fermenting.Maintainence:A great way to get your pot started is as a means of salvaging one of those batches that may havesoured faster than usual. Similar to continuous brewing, when you get ready to start a new brew youdraw the needed starter from the starter pot and replace it with freshly fermented KT.Only keep one or two spare cultures in the pot and replace them with the newest cultures which aren'tcurrently committed to a ferment. This helps slow down the accumulation of dead debris in the pot.When you remove the older cultures, squeeze out as much of the juice as possible to take advantage ofthe acid content and free some of the new cells to further boost the bacteria population.Filter the contents of the starter pot every 4 to 6 weeks to insure dead cells don't accumulate and causedetrimental side eects. When dead cells begin to stack up, the yeast will cannibalize them which canresult in some pretty nasty tastes and smells.Add distilled water to the pot as well, to compensate for any evaporative loss. Feel free to over


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compensate a little when you do. The bacteria seem to do better when fresh water is added and theirhealth is the main reason for using a starter pot.Only add fermented tea to the starter pot. This ensures the maximum amount of sucrose has beenconverted into glucose and fructose. Though not critical, this is fairly important because sucrose willstimulate the yeast where as glucose and fructose will not.This last minor detail is the number one contributor in keeping the culture balanced over successivegenerations. This is because glucose ensures the culture has fuel for activity without causing the yeastto go into the highly reproductive respiration mode, normally triggered by sucrose.

DOUBLING TECHNIQUEThe doubling technique is simply this:

Instead of adding all the sugar at one time add 15% the rst day, 30% the second and the balancethe third day.

This technique is great for helping a sluggish culture. Be forewarned that it is mainly designed toincrease yeast activity which is rarely necessary. But if you nd the ferment sours slowly and there islittle SCOBY growth, this should do the trick unless the culture has been contaminated.Kombucha normally takes advantage of an eect known to the beverage brewers world as the"Crabtree" eect. Simply stated, when too much glucose is present in the ferment, the yeast slow downand become almost comatose. They cease respiring (and with it reproduction) and switch tofermentation at a rather lethargic pace.Now to some degree this eect is desirable but if your culture is struggling then you can put it on thefast track by gradually adding the sugar over the life of the ferment so that the yeast only convert asmuch sucrose into glucose as the population can make use of. This will yeild higher rates ofreproduction which will be able to consume higher volumes of glucose as it becomes available.

DISCLAIMERI made this stu up so if you have any better theories let's hear them. Well OK it's not all ction. Whatyou have before you is the result of several years of tracking and recording of dierent KT formulas andtechniques coupled with knowledge I gained from the beer and wine brewing experts along with thedocumented research of KT done by Guenther Frank, Mike Roussin, Norbert Homan and PhilippeBlanc to name just a few.If there is anything in this document that contradicts known research you have possession of or candirect 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


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water, temperature, type and size of brewing vessel or anything else suspected ofcontributing to the problem.

EMAIL: Len Porzio


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Kombucha Fixing

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