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Is My SCOBY Dead? The Brewer's Quick Guide

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A dead SCOBY is quite distinctive due to its black color and the presence of mold growing on the surface.  Dead SCOBYs have a moldy aroma with the stench of rot. The pH of the brew in which the SCOBY has been for the last 10 to 14 days will also be above 4.5. this indicates that the SCOBY is no longer able to produce acetic acid continually indicating that the majority of the yeast and bacteria culture in it has died off.
Here at Grow You Pantry we grow our own SCOBYs! If you're interested in SCOBYs, or other kombucha accessories check out Our Store for the latest price.

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5 Signs Your SCOBY May Be Dead

1.  Change Of Color To Black
A healthy SCOBY’ color ranges from white to cream; as it gets older, the color will eventually turn greyish but when it dies, it becomes black. This is due to the death of the individual yeast and bacteria culture in the yeast.
It’s important to note that a healthy SCOBY will not always be white in color. Using it to brew green tea kombucha or using a different sugar source might result in variations in color range: from green to even slightly brownish or yellow shade. The only definitive color that indicates that the SCOBY is dead is black.
2.  Presence Of Mold
The presence of fuzzy mold growing on the surface of the SCOBY indicates that its defensive mechanisms have failed from protecting it; hence it is dead. A healthy SCOBY typically produces antibacterial and anti-fungal chemicals to defend itself and the brew. When this fails, mold will often grow either on the surface of the SCOBY or on the surface of the brew in which the SCOBY is submerged.
3.  The pH Of The Brew Containing The SCOBY
A healthy SCOBY continually breaks down dissolved sugar into acetic acid, which gives the brew a low pH of about 2.5 to 3.0. When the SCOBY dies, this process is brought to a halt and the brew in which the SCOBY is suspended in will lose its acidity driving the pH to over 4.5. The absence of an acidic pH in the brew also indicates that it can no longer defend against harmful bacterial growth which is usually held back by the acidic conditions.
4.  Rotten Smell
A healthy kombucha SCOBY has a vinegar-like smell, but when it starts decaying, it will develop a sharp cheese-like odor that gradually becomes rotten smelling like eggs. As the decaying process becomes more widespread on the SCOBY, the bad odor will also increase.
5.  Structural Breakage
A healthy SCOBY has a rubbery cloudy structure that often holds its shape even when it's young. A dead SCOBY loses this structural integrity and will break away easily when held. This is due to the loss of yeast and bacteria culture which produce the chemicals that hold the SCOBY intact.

What Causes SCOBYs To Dies?

1.  Contamination
A SCOBY will die if its culture gets contaminated with other harmful cultures. The introduction of foreign yeast and bacteria species to kombucha SCOBY often results in the loss of the balance that exists to protect the SCOBY. This can be in the form of:
  • Cross-contamination: whereby other fermentation cultures from a different brew invade the kombucha culture and harm the SCOBY. A classic example is using raw honey which contains its own live culture which kills the kombucha culture. It is important to note that Jun kombucha uses a different SCOBY that’s adapted to fermenting raw honey.
  • Unclean handling: handling the SCOBY with dirty hands or storing it in unclean equipment will often lead to contamination with harmful bacteria.
2.  Worn-out Culture
With each subsequent fermentation, a SCOBY grows and eventually, after about 12 batches it will have matured. After this, you may notice changes in the color of the SCOBY as it increasingly becomes full of dead yeast and bacteria culture. As the culture wears out, the replacement rate falls behind and eventually, the entire SCOBY turns black spelling an end to its usability.
3.  Non-Optimal Temperature
A SCOBY will die or go dormant when exposed to adverse temperatures which are beyond the optimal of 68-78 ºF (20- 30 ºC). Because the culture within the SCOBY cannot survive the extremes as temperature dramatically affects the metabolic process which keeps them alive. After prolonged exposure to over 90º F heat, the SCOBY will eventually die as the yeast and bacteria culture in it gets depleted.
4.  Sunlight
Sunlight contains harmful UV rays, which can kill the yeast and bacteria culture found in a SCOBY. Exposure to direct sunlight will dramatically reduce the population of the culture while also reducing its capability to reproduce. This eventually causes the SCOBY to die off as no new yeast and bacteria cells get produced, effectively stopping its growth.
5.  Using The Wrong Ingredients
Kombucha SCOBYs are highly sensitive to components used to set up the brew. Using the wrong ingredients to either sweeten or flavor the brew can lead to contamination with harmful bacteria and fungi which will destroy the SCOBY. It's recommended to stick to standard recipes when brewing kombucha to avoid such mishaps.


Signs of a Healthy SCOBY

1.  White To Creamy Color
A healthy SCOBY has a creamy whitish color that’s formed by the live yeast and bacteria culture. As the SCOBY gets older, the color may vary and will eventually turn greyish and finally black when it dies. Another factor that might affect the color of the SCOBY is the type of tea used to brew whereby green tea will result in a greenish tint and dark teas such as oolong and black tea will give the SCOBY a brownish hue.
2.  Low PH Of The Brew
A healthy SCOBY contains billions of live yeast and bacteria cells that continuously break down dissolved sugar into alcohol and finally to acetic acid giving the brew a low pH.  If your brew is taking much longer to gain a low pH and no change has after seven days, then the chances are that the SCOBY is not as healthy as it once was.
3.  Presence Of A Growing Baby SCOBY And Growth
A baby SCOBY will grow on most batches if the conditions are right. Its presence indicates that the mother SCOBY is healthy and that the right amount of sugar, tea leaves, and starter tea was used to set up the brew. Please note that the absence of a baby SCOBY should not be used to conclude that the brew or the mother SCOBY is unhealthy.
4.  Presence Of Brown Strings
The brown strings that generally grow around the SCOBY and accumulate at the bottom of the fermentation jar are yeasts. Their presence is an indication of the abundance of yeast culture in the brew.  The yeast feeds on the dissolved sugar breaking it down to alcohol which is then further broken down by the bacteria into acetic acid which protects the SCOBY culture ensuring that the symbiotic balance of the species continues.
5.  Kombucha Smell
A healthy SCOBY will have a slightly vinegary smell with hints of beer-like yeasty smell. The SCOBY may also gain the scent of the primary ingredients used to prepare the fresh tea. These include the flowery aroma of some tea varieties as well as that of the sweetening ingredient used such as molasses.



Is My SCOBY Dormant?

A SCOBY may become dormant, whereby the yeast and bacteria culture become inactive although they are not dead. once the conditions required by the culture are back to optimal levels, the inactive culture will start.
What Causes SCOBY Dormancy?
1.  Temperature
Low temperatures below 50 ºF (10 ºC) will deactivate the enzymes responsible for controlling metabolism in the yeast and bacteria culture causing the SCOBY to become inactive.
2.   Availability Of Nutrients
When the kombucha SCOBY lacks the required nutrients to feed on, such as sugar, it will become dormant until such nutrients are supplied once more. This is due to the reduced metabolic rate.
3.  Dehydration
SCOBYs can be dehydrated during shipment or long-term storage, making them dormant until such a time that it can be activated (link to how to activate a SCOBY).


Common Questions

How Long Does A SCOBY Last?
A SCOBY can last for up to 2 years if well taken care of. Generally, by its twelfth batch of fermentation, its health will start to deteriorate.
Can I Cut My SCOBY In Half?
Yes, you can cut a SCOBY into half and use individual halves to start separate brew batches.


Interested in learning more about kombucha? 
Check out these articles:
Kombucha Products
Kombucha and pH
Kombucha Bottles
Does Kombucha Go Bad?
How to Pronounce Kombucha

1 comment

  • My scone has sunk to the bottom of my kombucha mixture, has tidied or just resting and any particular reason for this, please?

    - Allan

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