For a few years we made чайный гриб (pronounced as chai-knee grib). This translates to tea mushroom. The beverage itself is sometimes known as grib which means “mushroom” or "fungus". I have read on the internet that it is also affectionately called gribok “little mushroom”, but have never heard anyone use this term. Most people in Australia call this drink kombucha.
Kombucha is sweet tea that has been fermented using SCOBY. If you make kombucha at home it is cheap and surprisingly simple to do. Many people flavour it with various things, while some of these are nice I prefer to drink it as is without flavouring.
SCOBY is an acronym for Symbiotic Culture of Bacteria and Yeast. Various studies have been done to count the number of species present in the scoby, while these numbers range dramatically depending on the scoby tested (and keeping in mind that each scoby will gain and/or lose species as time passes), kombucha often contains around 200 species with 20 bacteria and 16 yeast being the most dominant.
Other studies such as this one that was conducted over three years https://pmc.ncbi.nlm.nih.gov/articles/PMC8871122/ have recorded kombucha containing 320 different species. This study clearly demonstrates that the number of species, and abundance of each type, fluctuates significantly over time, and that the number of species/abundance of species is different in the liquid than it is in the pellicle/biofilm.
People often like to think that symbiosis means all the organisms working together in balanced harmony to benefit each other. The truth is far less romantic. Symbiosis only means different organisms living together for a period of time, symbiosis does not have to be mutually beneficial, or even beneficial at all.
In kombucha, all the organisms are competing for survival, some of them benefit from this arrangement, others less so, some even entrap and almost 'farm' others. These organisms competing for survival make the environment too harsh for non-beneficial organisms, while adding health benefits to the drink. It is a fascinating subject that is poorly researched, and no two scobys are exactly the same.
 |
| kombucha jellyfish |
Kombucha biofilm/pellicle
When making kombucha at home it often has a biofilm which is also known as a pellicle or a mother. The biofilm/pellicle is a flat thing that looks a bit like a pancake, or a jellyfish, (or a placenta). Some people refer to the pellicle as the scoby, while others aggressively attack them for using this term as it is not strictly accurate.
The pellicle is largely made of cellulose that is built by bacteria. The scoby lives in and on and under the pellicle, you could not separate them if you tried. The pellicle helps to protect the scoby, and helps the scoby survive if conditions are not ideal. Kombucha pellicles have been tested in the international space station to see how it protects against radiation etc - it is a fascinating subject. We don't fully understand how the pellicle works, or exactly what it does, but we know it has a role for the microorganisms interacting with each other and it has a role for protecting the microorganisms. While the pellicle is not the scoby, I don't see much harm in calling the pellicle the scoby, to me it seems like semantics.
While not ideal, it is possible to brew kombucha by simply adding a pellicle to sweetened tea.
This is possible, and I have done it, but things could go wrong. The main problem is the liquid will generally not be acidic enough to prevent undesirable microorganisms from growing in the liquid. Another issue with using the pellicle only is in the early stages most of the scoby are in/on the pellicle rather than mixed through the liquid. If starting kombucha with only using the pellicle, by the time enough of the scoby are thoroughly mixed through the liquid, and the pH is low enough, there may also be other microorganisms that have started to grow.
For this reason you should always include at least some starter tea when brewing kombucha. Most people add about 10% starter to 90% sweet tea, but I include a lot more starter. You could only use the pellicle and add something acidic to lower the pH, but it is easier and better to just include some starter tea.
 |
| Kombucha looks like a monster in a jar |
It is possible to brew kombucha by simply adding some starter liquid to sweet tea. I am told the finished kombucha brew tastes different than when the pellicle is also added. There is a higher chance of losing some species of microorganisms from your scoby when only using starter tea and not including any biofilm.
Fermenting kombucha using only the liquid and no pellicle works well enough because this liquid is often too acidic for many harmful microorganisms to thrive, the scoby are mixed through the liquid, and the scoby can multiply quickly and make the environment too harsh for other microorganisms to get a foothold.
Interestingly, the only times I have heard of kombucha going wrong was when people batch brew and/or are using only starter tea. Perhaps the pH is slightly too high, or there are not enough scoby living in the liquid and they struggled with cold temperatures, which allows mold to develop.
 |
| kombucha jellyfish in a jar |
For those who disagree with me that the pellicle/biofilm can be used effectively as an inoculum to brew kombucha, I thought I would include a link to a paper on this topic and quote some relevant parts.
https://pmc.ncbi.nlm.nih.gov/articles/PMC8371556/#:~:text=Kombucha%20pellicles%20are%20often%20used,part%20of%20the%20kombucha%20consortia.
The below talks about what the pellicle is, the different layers, and the role of entrapped yeasts:
The kombucha biofilm presents similarities to cellulosic pellicles grown by pure acetic acid bacteria (AAB) in sugared black tea but differs by the presence of yeast, which are involved from the early steps of biofilm formation. Based on observations, the formation model consists in an initial trapping and aggregation of yeasts (possibly in pseudo-mycelium form) in bacterial cellulose. With accumulation of cellulose and cells, a consistent layered pellicle is formed and, from then on, grows in thickness. The top layer at the interface with air is made of parallel cellulose fibrils and hosts yeasts and bacteria, while the bottom surface at the interface with liquid is made of cellulose network colonized by bacteria and where biomass accumulates. Finally, a middle layer located under the top cellulosic layer is filled with biomass and viable bacterial cells that are suspected to be the active agents of pellicle growth. This region is thought to play a nutritional function for bacteria by taking advantage of entrapped yeast metabolism and autolysis, thus revealing an aspect of the microbial interactions in kombucha. This study indicates that the yeast–AAB interactions in kombucha act on the structure and building of the pellicle, which could, in turn, enhance other types of interactions, including the metabolic interplay necessary for optimal kombucha production.
Some people brew kombucha without ever using a pellicle, and throw away every pellicle they see. While this seems to work well enough for them, they are reducing the metabolic interplay in their kombucha even if they don't know it. They are also slowly reducing the number of different species of microorganisms that are present.
Brewing kombucha using both starter tea as well as the pellicle is the traditional way that stood the test of time because it is very simple, and it has been demonstrated to produce a healthy result. Using both pellicle and starter tea is the traditional way to make kombucha, it helps maintain the highest diversity of microorganisms, and it is really hard for anything undesirable to start growing. I am yet to hear of anyone having issues when using both starter tea and pellicle to brew kombucha.
For someone who is just starting out brewing kombucha, it is easiest and safest to use both pellicle and starter tea.
The pellicle and the starter liquid both contain live SCOBY, and including both when brewing kombucha is simple and gives a beginner no real way to fail. Including both the pellicle and the starter tea ensures you will have the maximum diversity of microorganisms, it will have the maximum number of beneficial microbes, and it gives the best chance that they will be interacting in ways you want them to. The linked paper above demonstrates that in some years some species were present in biofilm that were not present in the liquid, other years they were present in the liquid but not the biofilm, other years they were present in both but at vastly different concentrations.
Once you have done a few kombucha brews and have a feel for how things should progress, as well as what looks normal, feel free to discard the pellicle and only brew using the liquid (which is simple), or to only use the pellicle (but only if you are very confident you know what you are doing). When you are still learning, or if you are planning on sharing your kombucha scoby with others, I strongly suggest using both the liquid and the pellicle.
If you are new to kombucha, and are buying scoby to get started, don't just buy a pellicle. Make sure you get pellicle and some of the starter liquid. While you can begin a kombucha brew with either just the biofilm, or just some starter liquid, it is better and easier to use both.
 |
| Kombucha |
Kombucha continuous brew
There are plenty of kombucha recipes on the internet. They all work because it is hard to go wrong brewing kombucha when you use both pellicle and starter liquid.
I tend to do continuous brew rather than messing around with batches and bottling and using fridge space. Continuous brew is the traditional method of brewing kombucha, it worked for generations of people, it works for me, it never goes wrong, it's cheap, and it takes very little time and effort.
Other people prefer batch brewing. This usually works for them, and they are often happy with the result.
They are both good methods, they both work, it is mostly personal preference.
 |
| Continuous brew чайный гриб |
You can see in the photo above I have a large jar that has a tap. It is simple, and can never fail unless the jar gets smashed or the tap falls out.
I don't put the lid on the jar as the scoby needs some air. I tend to keep a cloth on top of the jar, this keeps out insects and dust. I used to hold the cloth on with a rubber band, but stopped bothering with that a few years ago and it still does the trick.
You can see there are a bunch of pellicles in my jar. Once or twice a year I remove most to free up jar space for more liquid. Leaving the extras causes no problems, it helps things brew a little faster, and it ensures the diversity of microorganisms isn't slowly being reduced.
This blog post is getting a little long. Rather than make this post even longer, I wrote another blog post with the kombucha recipe I use.
No comments:
Post a Comment