center: Kombucha Hotel. Our recommended method of storing extra mushrooms. The thickness of the mushroom as well as the number is important to the health of the bacteria. Too many are a point of diminishing returns and become difficult for the bacteria to transport necessary nutrients. More information on this in our Kombucha Research & Library

[above ] carbon dioxide generated as a result of alcohol fermentation by yeasts accumulated in the interface between the pellicle and broth; this separated the mushroom from the broth and eventually, will block the transfer of nutrients from the broth to the top and the transfer of oxygen from the surface of the mushroom. These two deleterious effects lead to an anaerobic and starved environment. Few genera of yeasts and bacteria could survive such conditions. Therefore, viability of both yeasts and aerobic acetic acid bacteria decrease gradually during fermentation. My advice is to pop the bubbles as soon as they appear.  You want carbonation (a factor of the yeasts) but do not overdo it. To make really sparkling flavorful kombucha tea see our article on Bottling and Secondary Fermenting.

Yeast may hang down from the bottom of the mushroom. They may discolor as well as cause the mushroom not to form properly. Carbon dioxide produced from the yeast may create holes or bubbles  in the mushroom trying to escape.  Excess carbon dioxide will suffocate the acetobacter that produce the gluconic acid.

Normal thickness of the mushroom of a 8 day ferment at 79F  (26C) is about /8 - 1/4 inch (3-6 mm) The Thicker the mushroom the higher the gluconic acid and the lower the acetic acid.

The mushroom begins growing across the width. In the beginning it looks very much like mold. But in a few days it thickens and should be well formed. The mushroom relates to the health of the ferment and specifically the health and presence of the bacteria as well as to presence of foreign or unwanted bacteria and yeasts.

No mushroom forming and acetic  (vinegary taste) means that the yeasts - have taken over. Brettanomyces will produce acetic acid and alcohol but no gluconic acid.

Optimum temperature of a kombucha ferment is 74F - 84 F (21C - 29C). Below 70F produces inconsistent brews and diminishes the Acetobacter. Lactobacillus and some yeasts may thrive even in the Low 60's but the gluconic acid will not be produced. Low temperatures also give an opportunity for wild and airborne microbes to take hold and alter the ferment. Low temperatures always takes longer and produce a lighter color and taste ferment. Higher temperatures produce faster ferments and a darker thicker taste.

Different textures, or textures other than the typical creamy smooth mushrooms, are common in home ferments. However, even bad looking mushrooms may produce good kombucha tea.

Is my ferment healthy? 

Three main signs:

1. There is a film growing on top

2. Nothing fuzzy, dusty or colorful

3. A slight vinegar aroma

creations from other species of bacteria or yeasts

The next ferment may be different but if it continues to look bad we recommend to toss it out and start over.  It is apparent that the Gluconacetobacter are not home. And for that reason we always recommend to keep a spare mushroom happily brewing somewhere safe and quiet. see Kombucha Hotel above.

Bad Mushrooms and Mold (or do you say mould!)

Mold will be FUZZY it may also be very dry and dusty so do not try to smell it. The two below are not mold. The left one is spent yeast cells collecting on the top. When the kombucha mushroom has formed incompletely with different looking structures indicates something is not normal. On the right is not mold but the kombucha mushroom forming across with a bubble of what may be a different competing yeasts or bacteria. See online directions on How to Grow Kombucha Mushrooms http://www.happyherbalist.com/kombucha_brewing_guide.htm

Brewing kombucha is simply and easy. Yet at time a ferment may go off. This is true of other ferments as well, like beer, wine, and fermenting foods. So my advice is always to keep a spare safely tucked away and when in doubt - throw it out and start over.

Overactive yeasts may rush the ferment, form large bubbles and wild or minor yeasts may gain hold and begin to take over.

Mold most likely to occur will be fuzzy and appear as the common mold found everyday in foods. They will be dry and dusty - so do not inhale or attempt to smell as a severe nasal infection may occur. When the kombucha has significant acidity it will be anti-microbial and safe. Yet mold may appear on the outside or higher up. If the acetic kombucha tea is splashed onto the mold the mold will disappear - presumably destroyed. For health reasons I advise to toss out. The same risks that apply to any moldy food should apply. There have been no confirmed reports of contaminated kombucha tea adversely affected any individual.  see FDA and CDC talking papers on KT.

There are kombucha authors and brewers who say that when mold appears simply wash the mushroom off. You may face this decision at some point as mold may appear even after the most utmost care and experience. Depending upon the pH the tea itself may not be adversely affected. It is extremely disappointing especially when one otherwise beautiful perfect mushroom has just a tiny spot of mold. BUT ...

when in doubt throw it out. The cost of a gallon of ferment is usually way less than one dollar ...

Flowers of Wine:
Small flecks or blooms of white powder or film may appear on the surface. They may first appear as rings of white foam. If left unchecked, they grow to cover the entire surface and can grow quite thick.
Saccharomyces mycoderma produce flowers of wine, This is a off-ferment of the Saccharomyce yeasts used in wine and beer making and commonly in kombucha as well. Early wine books refer to these as Mycoderma vini. This is the yeast going off on a tangent and not doing the normal ferment one expects.
Flowers of wine are, of course are expected when using sherry yeast. This produces Flor, a sherry film on the surface of a ferment. Otherwise, in wines this is considered an off-ferment due to too much contact with air. In which case the ferment is then filtered or sulphites are used to save the wine. If you notice in the pictures below of fermenting beer and wine, you’ll see foam is natural and expected and produces a good ferment.

In kombucha brewing a film is expected to grow (i.e. the Kombucha Mushroom). Do not confuse the Saccharomyces mycoderma (S. Mycoderma) or Mycoderma vini with Mycoderma aceti (bacteria), which produce acetic acid and gluconic acid of our kombucha mushroom tea.

Flower of wine is not welcomed in popular ferments as they will consume our alcohol and acetic acid and leave water and carbon dioxide in its place.

This small ring of white foam or flowers of wine may also appear on kefir, viili, Caspian sea yogurt and other ferments as well. Although there, they appear as a separate film or layer easily distinguished from the main ferment growing underneath. Foam also appears on lacto-ferments like kim-chi and sauerkraut. This is commonly simply removed and the ferment allowed to continue - unless it is pinkish in color (pathogenic mold). Flower of wine, according to what I could find, have not been identified as pathogenic – other than to thwart ones effort. The taste of this “flowery kefir” is quite yeasty and distinct. In he case of kefir and wine, the advice seems to be just to scrape off. It does not otherwise interfere with kefir or the next batch. In kombucha fermenting it may be more difficult to control because if it is the yeasts (Saccharomyce) may be contributing and we need the yeasts to stop fooling around and produce what we want. We may be losing our ferment, since we rely upon the present ferment to produce a starter for our next brew as well. The next few batches will tell as the mushroom becomes thinner and weaker and the kombucha tea less flavorful.
 

Vinegar eels and Vinegar flies   see cautions and tips

Bad kombucha close up

Other ferments

never found out what this one was ..

On the right is a one-inch thick mother-of-vinegar that took about 6 months to produce.

Most MOV grows on top and is very similar to a kombucha mushroom and would be impossible to tell the difference from just looking.   However MOV may also grow in a more loosely jelly-like structure that floats midway in the liquid. Many early Kombucha books recommended to throw out your "kombucha" if it sank (did not float on the top) believing it might be MOV. In my opinion and others, is that a kombucha mushroom may float or sink or even go sideways and move about, it will still produce good Kombucha Mushroom Tea (acetic acid, gluconic acid an fructose)

from http://mars.ark.com/~squeeze/mother.html

The difference between Vinegar (MOV) and Kombucha, which are produced from the same genius of bacteria (Acetobacter) is that kombucha has gluconic acid, vinegar does not. This is a result of the different fermentation methods used. The difference between Kombucha and LAB ferments (Ginger Beer, Water Kefir, et al) is the species of bacteria - LAB (Lactobacillus bacterium) versus Acetobacter = Kombucha. Again the major difference is gluconic acid.  All these ferments may look and taste the same. There is not a simple home test that I am aware of that one may test for gluconic acid which is the distinguishing feature of true kombucha mushroom tea.

A large mushroom drying for Commercial application from Acetobacter Xylinum

many folks use the mushroom to make works of art and even Drum skins

And finally the mushroom itself. Many potential high value markets exist for thin film bacterial cellulose, including acoustic diaphragms , artificial skin, artificial blood vessels, liquid loaded medical pads, super-sorbers  and specialty membranes.  Potential markets for bacterial cellulose produced as pellets in agitated culture include the mining industry, the oil industry, foods, and the pulp and paper industry.

[source: Production of Bacterial Cellulose from Alternate Feedstocks. D. N. Thompson M. A. Hamilton. May 7, 2000 – May 11, 2000

22 nd  Symposium on Biotechnology for Fuels and Chemicals]

and YES, it is edible.  

dogs, horses and other creatures love them. For more ideas on what to do with extra mushrooms, and too sour kombucha tea see our article.

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