Let’s talk pellicles.
A pellicle refers to the membrane or skin. During kombucha fermentation, a pellicle will form on the surface or air-liquid barrier. This little (or sometimes very big if left alone) membrane has become the face of kombucha, sometimes referred to as the mother, mushroom, baby, or simply SCOBY.
SCOBY stands for Symbiotic Culture Of Bacteria and Yeast and refers to the microbes in kombucha.
Culturally, though, it has become common for “SCOBY” to refer simply to the pellicle.
The pellicle is made up of bacterial cellulose. Fun fact: cellulose, typically associated with the cell walls of plants, is also produced by bacteria! Bacteria are so cool!
The synthesis of bacterial cellulose is a side effect of the fermentation processes, not the ultimate goal of tasty kombucha.
If no cellulose is produced, aka no pellicle forms, does this mean that the bacteria are dead or not fermenting? No. It just means they aren’t producing cellulose but are doing other microbial things, which is totally okay. This is good news if you are worried that your culture is not “making a baby.”
If your kombucha isn’t reproducing a pellicle, yet all other signs are pointing to fermentation (lowered pH, lightening of color, vinegary scent, signs of bubbles, no signs of mold, and tastes good) then continue on brewing. Over consecutive brews, you will most likely get pellicle production if it’s not happening right away. Even though it’s comforting to see a pellicle growing as a sign of a healthy fermentation, it isn’t all or nothing.
If you are trying to increase the production of cellulose, try aerating your brew early on by stirring vigorously. This extra oxygen can help boost pellicle production.
What should the pellicle look like? There’s no one answer. Kombucha pellicles can grow in all sorts of weird textures, and grow to the size of the container that they’re brewed in. The structure is comprised of cellulose sheets that bond together vertically, which results in a thickening appearance over time. At the beginning of the brew, it will be just super-thin microfilm. This is when most newbies start to get concerned if they’re doing things right or not. The film is translucent at this time, showing yeast globs forming underneath–alien looking stuff to an untrained eye. Once the film begins to thicken, it looks more familiar, gains a waxy, white or tan appearance, and sighs of relief start to reassure the new brewer that all is right in their microbial world.
There’s no one perfect way for a pellicle to look, so don’t worry if yours looks off-putting. Just love it anyway and tell it that it’s special.
Here are some examples of healthy new growth:
And here’s some healthy established growth:
Notice that on the first photo, the pellicle has sunk to the bottom–all good because a new one will form on the top, just like in the second photo where you can see the layering. In the third photo, you can see that the pellicle is raised off of the liquid almost an inch at parts–this happens when carbonation builds up and pushes the pellicle up to escape–you can either push it down or just let it be.