Monthly Archives: February 2016
A Common Problem :
My Kombucha tastes like vinegar.
My kombucha ferments so fast I can't control it.
Time and time again, it is because they were trying the continuous brew method. Sometimes they only continuous brewed for a few weeks before noticing a dip in quality. When they attempted to revert to batch brewing with the same culture, they discovered they had fundamentally changed the culture and could not get it back to its former glory. Here is our educated assumption of what is happening....
Succession is the observed process of change in the species structure of an ecological community over time. Many multi-species ferments are successive in their microbial activity meaning that in the beginning of the fermentation process, a certain species or set of species is active. As their activity changes the composition of the substrate (making it more acidic, for example), the conditions become unfavorable to those first pioneering species. They grow sluggish and eventually halt their activity while the new conditions they created are prime real estate for the next wave of species to succeed. And this can happen several times throughout a fermentation process.
The succession process in fermentation is highly studied and documented in sauerkraut. In the beginning of sauerkraut fermentation, Leuconostoc mesenteroides is the pioneering species that gets going first. As this bacteria proliferates and its acid-producing activity lowers the pH in the crock, the conditions become intolerable for it. It’s kind of like if you keep setting up more and more kombucha brews in your kitchen, eventually it will become so overwhelmingly acidic smelling in there you won’t be able to go in without a respirator. (Believe me, we know). So, once Leuconostoc mesenteroides has chopped its nose off despite its face, other species in the crock that love lower pH conditions, like Lactobacillus plantarum and Luteimonas cucumeris, wake up and shine! They get active digesting stuff, transforming stuff, creating their own styles of acids that then lower the pH even more. They have their time in the limelight and then the conditions become intolerable to them (again by their own activity!) and they stagnate. But those low low pH conditions are perfect for the next round of fermenting bacteria to set up shop and Lactobacillus brevis begin their heyday creating their own signature acids.
With each wave of microbial activity, a new set of compounds is created and it is the layering of these compounds in succession that creates the complex health attributes and delicious characteristics of finely made sauerkraut. One would not throw a cabbage into a crock with only the last round of bacteria and expect it to yield the same delightful results as a ferment that has gone through all of the natural stages of complex fermentation . No no no.
And this explains why we don’t advocate continuously brewing kombucha. In our years of experience in home fermenting and commercially brewing kombucha, we have never tasted a kombucha made using the continuous brewing method that meets our standards for a robust, complex and delightful 'buch. Continuous brewed kombucha results in a profile that skews toward too much acetic acid. You can tell because it tastes like vinegar.
Not only that, but kombucha cultures that have at some point in the their history gone through a period of continuous brewing seem to lose the ability to ferment at the earlier stages altogether – the cultures seem to have lost the pioneering species and have become concentrated with the microbial species typical of later stages of fermentation. You can always tell a SCOBY has a continuous brew heritage by the immediate formation of the “vinegar” flavor that is characteristic of acetic acid just hours after a new batch is inoculated. This is not the kombucha that we like to drink and we think it may not have the same nutritive characteristics as those that are allowed to go through all stages of fermentation in batch brewing. We have also never seen a SCOBY recover their pioneering abilities.
If you are in the market for a new SCOBY, we highly recommend you start with a SCOBY guaranteed to have never been used to continuously brew kombucha. Your crock, palette and belly will thank you.
Most kombucha brewers are aware, to an extent, of the prevalence of hearsay and unfounded rhetoric surrounding every facet of the kombucha experience. The ongoing conversations are what fuels, to a great extent, the content of this particular blog, while also contributing to a modern kombucha mythos.
Power of direct experience
To be absolutely honest, though, so much content must be experiential due to the simple fact that obtaining actual research on the subject of kombucha can be difficult. The small amount of research that has been done can be difficult or expensive to access. The things we discover in our own experiences, or those of others, are excellent sources. Experiential data holds great weight for home brewers.
Sure, it can be useful to cite x or y article that references the 'buch. These impressions will always exist, and the weight we contribute to them is of course a matter of our own willingness to accept or reject these and other sometimes unfounded suppositions. As with any data on the internet, though, check your sources.
Reports that hold salt
There is some excellent data we can all point towards, either to support or helpfully reject some facets of our experiential understanding. Excellent sources include a number of books and scientific papers.
One great source we've recently discovered, though, is a portal to all sorts of scientific knowledge previously accessible only to those willing to pay for it. However, we see that the idealization of the free flow of information has issued into a vast majority of science literature being made freely available. An article about the woman behind this democratizing action, and a link to her eye-opening project can be found here. A simple search for "kombucha" on her hub yields quite a number of papers that point to scientifically-tested aspects of our favorite beverage.
The ever-useful Reddit also has a section titled Scholar - and, doing a quick search for "kombucha" here can bring up a good amount of scientifically-verified data on the 'buch!
Kombucha cohorts over at the Happy Herbalist have compiled a useful page as well, citing some of these studies, which can be found here. Referenced is one of the major studies about kombucha, performed by Michael Roussin, for example. In his research, one of many things he revealed is that caffeine content of teas is not affected by fermentation. It is notable that this research runs contrary to the popular belief that kombucha fermentation helps to mitigate caffeine from the tea's infusion - good information for those with caffeine allergies to know before embarking on a brewing project, but also a great example of the potential of science to debunk a common bit of kombucha mythology.
As with many things in our own lives, the phrase "you decide your own level of involvement" rings loud and clear when we attempt to build up our knowledge base with regards to kombucha. Our own direct experience can be incredibly powerful, but when bolstered by scientific findings, we can come much closer to a full-circle understanding that enriches our brewing experience and propels our lives towards vitality and happiness. Happy brewing!