The Difference Between White SCOBY, Yellow SCOBY and Brown SCOBY Colors
Why Do SCOBYs Colors Vary So Much!?
The colors of kombucha SCOBY cultures can vary immensely from pearly white, to dark brown. Often first time brewers become concerned that their brewing culture has gone off due to darkening or other SCOBY morphing moves.
Although there are some events to watch out for which the appearance of your culture can indicate, such as mold or an imbalance between the microbes – most often strange looking SCOBYs are totally fine!
If you want to know more about what a healthy brew looks like, you can check out Top Signs of a Healthy Kombucha Brew.
Although color variances and other appearance changes in kombucha SCOBY cultures are usually not anything to worry about, it is nice to know what is going on, or which factors play a role in what your SCOBY looks like.
Normal Colors for SCOBYS
Although SCOBYs can be very different in shapes and shades, there is a range of colors which are normal for SCOBYs. The three main colors along this range are off-white, cream/yellow, and dark brown. While all of these are quite acceptable colors for SCOBYs to take on, it is interesting to understand what factors produce which colors. You can read our What SCOBY Color is the Healthiest article for more info.
White SCOBYs are usually SCOBYs which are either young, have very low populations of yeasts, and/or have been brewed in a non-staining tea such as green tea. When cultures are young they are typically quite pale in color. The more time that passes in which they are exposed to tea which contains staining tannins, the darker they become.
The other thing which can play a role is the fact that the yeasts within the SCOBY culture have the tendency to clump together in brownish blobs of yeast cells. It is possible to see these floating freely in the brewing kombucha and settling on the bottom. They also accumulate within the cellulose tissues of the culture and result in darkening.
Yellow or cream colored SCOBYs are usually ‘middle aged’ cultures. Meaning that they have been through a few brews, but have not been severely stained yet, and do not have an overly large population of yeasts in their cellulose tissue. Note that sometimes when a new SCOBY layer starts forming on the surface of a brew, it can look yellow in color. This however is the effect of dark tea shining through the still translucent skin-like new SCOBY, and giving the illusion that the new culture is yellow.
Brown SCOBYs are usually quite old and have been through numerous brews, or have been stored in a SCOBY hotel for quite some time. They have been stained heavily by the brewing tea, or storage tea, and might also have high populations of yeasts within the culture. While a very brown culture is not as attractive as a pretty pearly white one, a dark color does not mean that the culture is dead, or that it cannot carry out fermentation.
SCOBYs may get old and lose their vitality and brewing power, but older SCOBYs can still get the job done, and if you want to brew with a new culture just wait for one to form! While kombucha brewers often warn against the event of overactive yeasts in SCOBYs, as long as the bacteria are also going strong, signs of good sized yeast populations are not something to be too concerned about. However, if you have not been brewing for that long with your mother culture, the culture is starting to darken, and you are wondering if your yeasts are on overdrive, you can check out this post for guidelines on what to do What to Do If There is Too Much Fizz in My Kombucha.
When Dark is too Dark
While dark colored cultures are absolutely fine to use, and not sick in any way, it is a good practice to select the whitest and densest SCOBY when the time has come to retire your brewing friend and choose a new mother SCOBY. As the yeasts tend to become more dominant with time, selecting a paler culture for a new brewing SCOBY is a good move, as this means that you will have more time to brew before experiencing a dominance of the yeasts.
Although it is good to swap out your cultures regularly for fresh young ones, it is possible to continue brewing with very brown and mature SCOBYs and get good ferments. You can continue to brew with the same culture as long as you are getting desirable batches.
However if you notice that your culture is starting to shed dark dried looking layers, then it might be a good time to swap it out. These layers are dead material which does not need to be part of the culture any more. While this dead matter is not potentially harmful to anyone who drinks the finished kombucha, it is not necessary to have it floating around in your brew.
specially seeing as kombucha usually produces new SCOBYs by the handfuls! If you are not getting any baby SCOBYs, or not experiencing any thickening of your mother culture, have a look at this post for possible causes What To Do If No SCOBY Forms In My Kombucha.
When brewing kombucha, you can be prepared for all sorts of weird looking phenomenon in your culture. From lumps to holes and pale to dark, SCOBYs come in all forms. If your culture is looking really strange and you are wondering if everything is still ok, one of the best rules of thumb is to give it a smell.
Properly fermenting kombucha usually has a smell that is sweet/sour. The longer the brew has been fermenting for the sourer it will smell. If you encounter anything the smells off or unappetizing, this is usually a good indication that there is something wrong and you likely do not have a healthy Kombucha SCOBY.
Note that one exception to this rule is a sulfurous or ‘rotten egg’ smell. This is often simple to sort out and not a sign of an off brew or rotting culture. If you are encountering this and want to know what is going on and how to fix it, read Why My Kombucha Smell Like Sulfur (or Rotten Eggs) to find out more.