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Succession and Why We NEVER Continuous Brew

A Common Problem :

My Kombucha tastes like vinegar.

or

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.

 

Jun sample

 

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.

38 thoughts on “Succession and Why We NEVER Continuous Brew”

  • Jackie Edwards

    Well, I think you may have answered my question before I asked it. I have been making Kombucha for about 2 years, using a Scoby I originally purchased from you. I had great results. I started continuous brewing about 3 months ago, and lately my brew has not been the same quality as before. Too acidic tasting, and then this week, despite my careful precautions, one of the continuous brew jars had an infestation of fruit flies. I threw everything out, rewashed and sterilized everything, took half of the scoby from my second continuous brew jar that was not contaminated, and started again. I think now I just need to start over and go back to my gallon jar method with new scobys. Do you have any suggestions for the fruit flies? I use Tee Shirt material over the top with a rubber band securing it. My grandson made me a fruit fly trap which I set out in front of the jars, and I always seem to catch a few. They have become quite a problem, where they never were before. I usually have 3 or 4 gallon jars fermenting each week, and everyone really enjoys the Kombucha.

    Reply
    • Chris

      Hi Jackie, as for fruit flies, it's as simple as keeping the brew jar covered - a tee-shirt type material is just fine. Many people think that cheese cloth is okay to use, but in fact the weave is too porous. Let us know how it goes, and happy brewing!

      Reply
  • Matt

    Hello,

    I guess I've been doing a variant on the continuous brew. I have a 3 gallon crock, and as the buch ferments to how I like it I siphon off everything except for an inch or so of liquid at the bottom and put it into growlers. Then I put the growlers into the fridge to stop the fermenting. The 1 inch brew sits for a week or so in the crock at room temperature while I drink from the growlers, then I add another 3 gallons of sugared tea and go from there. I would think this would allow all stages of bacteria to co-exist as the ph would go almost to neutral when I add the new tea.

    Is this correct, or do I need to do something different?

    Thanks,

    Matt

    Reply
  • Tony

    Sorry in advance for the dense question I'm about to ask, but I think I'm missing something here. I was definitely having a problem with my brews having a heavy vinegar flavor. I just couldn't get it to taste good. Long story short I am in the market to start brewing again with a new scoby soon. So, in the past my routine was to brew a 1 gallon batch, & let it ferment for about 14 days (I think this was too long now). Then at the end of 14 days, would brew another batch, bottle the first, then set up the next batch using the 2 scobys from the freshly bottled batch. The 3rd batch, I would get rid of the 1st brews scoby only keeping the most recent 2 scobys in a brew at a time. rinse and repeat. Is this what you're referring to in regards to "Continuous Brew"? Or is continuous brewing something else entirely?

    Reply
  • Deirdre

    Help! What exactly is continuous brewing, and what is the correct way to home brew? I think I'm "continuous brewing" currently.

    Reply
    • Chris

      For the purposes of this article, I would define continuous brewing as the practice of periodically removing and "topping off" a kombucha brew without ever removing a majority of the brew. You might describe, then, "continuous batch" as removing 90%, leaving 10% as starter for the next brew, and refilling with sweet tea - though I would call this standard, and not "continuous" at all. Hope this helps!

      Reply
  • Bonita Fisher

    Wow - and you have answered mine as well, I suspect. Not so much from continuous brew, as from leaving the 'buch to brew *too* long, repeatedly. As in, trips abroad, busy with home and work - in fact, months-worth . . albeit at ~ 68-70 degrees. So, often I have wondered about just this thing - if I was losing certain healthful species to a plethora of low-pH species.
    Hmmm - now to figure if I must start . . again . . !

    Reply
  • Jo

    I use an unbleached coffee filter with a Rubberband to keep the flies out

    Reply
    • Gibson

      Great explanation of the details regarding each bacterial strains' lifecycle and needs. Very interesting and definitely helps to better understand fermentation/brewing as a general topic.

      I have personally only been brewing since the beginning of March, harvesting my first batch (48 oz mason jar) at around day 18. The SCOBY I used was one I grew over a period of 45 days from a bottle of GT's Original (the "non-reformulated" version). I found the taste akin to commercially-available booch, but definitely having a more vinegary taste and in general just more "raw" (both in a good way). I have a second batch brewing now with both the first SCOBY and the baby SCOBY grown during the first brew.

      Should I be concerned about my SCOBYs' lineage, coming from that bottle of Original? Or is it safe to assume GT's brews in batch, and thus any cultures stemming from that will be fairly healthy?

      Thank you!

      Reply
  • Ann {Created To Cook}

    Fascinating article... And now it's got me wondering... You know how raw apple cider vinegar is suppose to have all these health benefits and be able to help control blood sugar levels. I wonder if Kombucha left to ferment into Kombucha vinegar would have similar health benefits. I wonder if this has ever been tested in a lab. Have you guys had much experience with cooking with and using Kombucha vinegar???

    Reply
    • Eric Childs

      Ann, great thought! I would love to see the levels of acetic acid in both apple cider vinegar and kombucha vinegar. Im sure they are much the same. We have tons of recipes using KB vinegar! Check out our book.

      Reply
  • Lisa

    You said you recommended starting with a new scoby that had not been from continuous brew, but could you grow a new baby Scoby and separate it from the old one (that was from continuous bew) and be ok?

    Reply
  • Jack Wilson

    What should the pH be? I have been using the continuous brewing method and if I leave it too long it will get a vinegar smell and taste, I just find that I have to bottle it quicker.

    Reply
  • Michael cokkinos
    Michael cokkinos April 13, 2016 at 8:30 am

    Sucsession brew in a continuous vessel

    I just set up a system where I brew in a spigot glass carboy then bottle everything but 2 cups for the next batch
    Add sweet tea and ferment

    Is this considered continuous?

    Reply
  • Marlene

    When my gallon jar is ready to bottle there is sediment in the bottom. Should it be mixed in before bottling, or discarded.

    Reply
  • Blake G

    Very interesting article, but i'm left a bit confused with the plethora of opinions i have read on proper brewing.

    Where does this leave the SCOBY hotel? It would seem to follow logically that because they are usually stagnated for long periods of time they too would lose their ability to ferment at earlier stages. Leaving them "duds"

    Also, i have been looking to upgrade to a charred and aged oak barrel as a brewing vessel for my Jun as i've heard of a nice flavor being infused into the brew; But this method seems to always use a continuous brew method. Would a batch brew method still give that extra flavor with so little time in the barrel?

    Reply
    • Eric Childs

      Blake, you should store your SCOBY hotel in the fridge to lock in the microbial content. It can stay unchanged for up to 3 months. After that time it is best to cycle through the SCOBY stored.

      An oak barrel can be used for batch brewing and makes some amazing kombucha. Let us know what you come up with!

      Reply
  • Cheryl

    my buch turned to vinegar, I removed my SCOBY and saved 2 cups of liquid in a qt ziplock bag, should I wait before starting another batch, and where should I keep my SCOBY/starter? fridge or room temp? FYI I found a sticky thermometer at the pet store for $2, it is on my buch jar.

    Reply
  • Stefanie

    Ah! So what about if you're taking a break from brewing - I have my scoby in a jar and I have been pouring off half the liquid and replacing it with sweet tea every so often....just to keep it going...but this is awfully close to a continuous brew situation! Am I killing it? Thanks!!!

    Reply
    • Eric Childs

      Stefanie, the only way to store a SCOBY without it changing is to put it in the fridge along with fresh kombucha. You can keep it like that for 3 months without much change.

      Reply
  • Frankie

    Hello, thank you so much for this information. Most of the web is crazy for continuous brew. We have just had our kombucha turn too vinegary too quickly from continuous brew. If we buy new scobies can we use our kombucha from these continuous brews as starter but buy new scobies? You say that you've never seen scobies turn back after continuous brew, but buying all new scobies would be rather costly. Is it the scobies, kombucha or both? Thanks for your input

    Reply
  • Lindsay

    I am new to home brewing and I am a little confused after reading this article. I want to describe to you my process and I would really appreciate your input:

    I use a Jun scoby and a 1.5 gal vessel with a spigot. I add about 1.2 gal of green tea sweetened with 1C of honey to the vessel and put the scoby on top. I let it sit for about 3-4 days depending on how hot it is in the house then use the spigot to bottle up my brew (I keep a little medicine dispensing cup on top and taste it from the spigot to see if it's getting vinegary). On day 3 or 4 I bottle the tea using the spigot. I do not stir the tea before bottling it. I then reserve about a cup of it from the spigot for my next batch, discard the sludge at the bottom, rinse the vessel, clean my scobies and start again. I left the sludge in the bottom the first couple of times as my starter, but feel like there is too much yeast in it and it makes the brew sour so fast that I started feeding it to my house plants instead. Is this they way to do it? Thanks so much for your awesome website.

    One more question: My husband and I are doing a ketosis reset diet and we want to know how many carbs (approximately) are in a 16oz bottle of plan jun that has had a second ferment. If you have any input here, that would be greatly appreciated! Thanks so much!

    Lindsay Behr

    Reply
    • Eric Childs

      Lindsay, you're doing great! This is exactly what you should be doing. I hope you are still enjoying your brew. Im not sure about JUN but tradition kombucha has around 10g of carbs per 16oz serving.

      Reply
  • John

    So if Continuous Brew is not a good,

    so how long do we have to wait for next batch then leave 90% of the fermented and put a new batch of tea?

    Its good to know the Continuous Brew is not good but the solution towards isn't very clear.

    Reply
    • Eric Childs

      Hi John. The best way is to first remove your starter liquid for your next batch. Then bottle all but the last 1/2" of kombucha in your jar. That last bit is full of yeast and can be dumped. This will help keep the yeast colony in check. Rinse your brew vessel then start again using all new sweet tea, the starter liquid you set aside and ONLY the new SCOBY that formed on the surface of your last brew.

      Reply
  • Oscar Angulo

    Hey chris. Here's what i do. I make 2.5 gallons of oolong tea kombucha using one large scoby and a regular size(but multiplying) scoby. I let it ferment for 10-12 days in room temperature and then bottle it with whatever flavor my family wants. I leave about 15% for the starter batch which i start right away. so far, everything seems to come out fine. Is what i'm doing ok? will it have any effect on my scoby or my finish batch in time?

    Reply
    • Eric Childs

      Hi Oscar. You're doing great! The only improvement I would make would be saving the first 2.5cups of kombucha for your starter liquid and not your last. We dump the last inch of brew that is full of yeasty sediment. This helps keep the yeast colony in check. Also get rid of all old SCOBY and keep only the new.

      Reply
  • Pamela

    I always wondered why my batches always tasted so vinegary. Thank you for the explanation.

    Reply
  • Sam

    Thanks so much for all the tips on this site as well as this helpful article reaffirming my batch brew method. I'm a homebrew beer guy, who always keeps a batch of buch on the side, cuz it's so darn easy and so damn tasty in the morning back sweetened with some tropical fruit medley... anyway, I just had my first mold infection on a 4 gallon batch I've had going for over 7 YEARS! I know you warn against anthropomorphizing your SCOBY, but I am still in mourning since this morning, and wondering what I did wrong or differently this time around. I think I must have left a finished batches sitting through past winters in a sort of "hibernation" and making a new batch in the middle of winter this year did not bode well for the culture, which left the door open for some errant mold to take hold. aaanyway, I'm taking this all as a learning experience as I plan start completely over with a brand new batch this weekend after the New York City Fermentation Festival. Hope to see you there.

    Reply
    • Eric Childs

      Hi Sam,
      Sorry to hear about the mold but it happens. Dont fret it. Were you using the same SCOBY each time over the last 7 years?? Best way to keep a full spectrum highly active SCOBY is using the newly formed SCOBY on the surface along with fresh starter liquid. If you have been doing that the most common cause for mold is temperature if below 68F. Also improper acidification. If you have a PH meter make sure your sweet tea is at a PH of 3.6-3.8 at the start of fermentation. This will ensure no mold will form if you have an active culture. Hit us up on email if you have any more follow up questions and Happy brewing!
      Come visit us in Kingston!

      Reply
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