Learn to read your Scoby

topic posted Thu, February 25, 2010 - 12:17 AM by  Mv
Scoby too thin ? 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.

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 insure 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. Do not place near dirty air vents or in kitchens with cooking smoke, or any smoke for that matter.

Don't wash your fermenting vessel with antibacterial soap. 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. Do not use chlorinated water. Best is to use pure distilled vinegar.

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 21C degrees (70F) try to get it up a few more degrees to about 23C (74F).

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.


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.


If you have a lumpy one, this is one of those 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 read something once by one of the renowned KT researchers that this may be 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.


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.


If your scoby is climbing out of the 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.


Is your scoby a sinker? 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.


If you have NO baby scoby, Not much you can do in this situation. There has to be at least some surface formation to recover. If you see at least the beginning of a clear film on the surface then you need to Increase the Ratio of Acetobacter to Yeast Populations. 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, or any sort of smoke. (including kitchens)

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 your ferment is too 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 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.


If your ferment is syrupy ... My brother'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 his city water. (I use straight well water.)

If this happens, 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 pure distilled vinegar before using it again.

This assumes you're using the standard 160 grams of sugar per 2 Liters 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.


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 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") 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. Since the yeast can reproduce with or without surface air they have a slight advantage over the bacteria that rely on air for reproduction.


If your brew is 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.


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.


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.


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 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.
posted by:
offline Mv

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