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-   -   SCOBYs Are Useless (http://www.homebrewtalk.com/f167/scobys-useless-343140/)

Sdaji 07-23-2012 12:16 PM

SCOBYs Are Useless
 
I've been experimenting with not using SCOBYs when setting up cultures. I get lovely, thick, well-formed SCOBYs. I started wondering how adding a SCOBY was doing anything, since I heard about other people using the old SCOBY to make their next batch. The old SCOBY is submerged, sometimes even sitting at the bottom of the jar. The SCOBY of course is where the bacteria sit at the surface, so they can stay wet but have access to lots of oxygen. If the SCOBY isn't on the surface it's just a meaningless piece of cellulose, and that's what lots of people use rather than the active one on top.

I tried making cultures without SCOBYs. Not surprisingly, they grow SCOBYs just as quickly as the cultures with starter SCOBYs. I usually add about 10-15% kombucha and 85-90% sweet tea, and a SCOBY (or piece of one). If I make two batches side by side and give one a SCOBY and the other the same volume in extra kombucha, the one without the starter SCOBY actually brews faster and grows a new SCOBY more quickly, with no difference in 'quality' (as judged by my taste buds), just a slightly shorter brewing time. I interpret that as there being more microbes in the liquid than in the SCOBY (which is basically just permeable cellulose with a bit of liquid). I did wonder if there would be lots of bacteria in the SCOBY and more yeast in the liquid, and perhaps that is the case, but either way, there is obviously plenty of everything in the liquid.

I think using old SCOBYs is especially meaningless. You're just putting some inert byproduct into your new culture.

porcupine73 08-21-2012 05:52 PM

Right the scoby isn't absolutely needed if you have enough starter tea in the mix. It is a bit of an art to keep the scoby at the top when cleaning out the brewer or starting a new batch. I'd say my scobies float, sometimes with a little help, about 75% of the time. Sometimes they insist on sitting about an inch below the top and then of course a whole new scoby grows.

Sdaji 09-05-2012 03:28 AM

I've tried it in side by side brews lots of times now. Say, a litre of new sweet tea in each, 50ml of liquid and a 50ml SCOBY in one and 100ml of liquid and no SCOBY in the other. It seems the liquid actually contains more microbes, or maybe it's that the extra starter tea reduces the pH and adds more alcohol etc. than a SCOBY would so the new brew gets going faster. Either way, it's not just that the SCOBY isn't necessary, it doesn't even seem beneficial. I'm actually wondering if the SCOBY is even something the bacteria build to give themselves a place to live, or if it's just the the cellulose is a byproduct they produce and since they are active at the surface that's where the cellulose is created. If so, the SCOBY might actually just be a waste product which gets in the way and stops the brew working as well by creating a barrier between the liquid and air. Obviously it's not a significant problem and I wouldn't bother trying to remove the SCOBY mid brew, but I wonder if it's actually a slight problem or a benefit having a SCOBY there at any time. Certainly, the term SCOBY seems like a complete misnomer.

porcupine73 09-05-2012 12:49 PM

Hm well it's definitely an interesting observation. Maybe you're right about it being a waste product, since the scoby seems to just grow and grow and grow and eventually will take over the entire brewer if it gets the chance.

I was thinking more about this today, maybe you could do this as an experiment? How about every day or every other day you scoop of any scoby that has started to form? And compare that with a batch where the scoby is allowed to grow normally, to see how the end products of each are?

saramc 09-07-2012 01:43 PM

I personally do not think SCOBY's are useless. Case in point, I started a batch of kombucha and forgot to add the starter tea (did not realize until MANY days later), but had added my SCOBY as usual and my kombucha turned out just fine (took it a bit longer but it was just fine). Also, I do not believe that a sunken SCOBY is a dead SCOBY--many different school of thought on floating vs. non-floating. I replace a SCOBY when it actually starts to shrink, it is a visual inspection for me. FWIW.

Sdaji 09-12-2012 07:11 AM

porcupine: I've wondered about that. I imagine it would brew normally, but it would be interesting to try.

saramc: The 'SCOBY' is porous, like a sponge. I could get the exact same result you did by putting a plastic sponge in some liquid kombucha and putting that into the starter tea. It wasn't the inert cellulose that made your brew work, it was the microbes and liquid in the SCOBY. Alternatively, I could get a SCOBY, dry it out, sterilise it, soak it in kombucha then put it into some sweet tea and make a new batch. Alternatively you could get a SCOBY and wring it out so the expelled liquid falls into a new batch of sweet tea. That would work too. It's possible that the bacteria adhere to the SCOBY and have higher numbers there than in suspension, but your experience actually suggests against that, because your brew took longer. I must admit, I haven't tried using SCOBY only with no liquid to start a new brew. I'll give it a go some time, comparing an equal volume of SCOBY alone to liquid alone.

The SCOBY is never 'alive', so no, a sunken SCOBY is not a dead SCOBY, it's just a sunken mass of cellulose which used to be a floating mass of cellulose.

The SCOBY itself is very clearly not a 'plant' or 'mushroom' or any sort of living thing. They never grow, new layers of cellulose just get piled up at the surface of a kombucha culture. If there's already a layer right at the surface the new cellulose is attached to the old and the mass gets larger. If the top gets covered by liquid the new cellulose just piles up above it in a new layer. It is not stored for later use, it is inert, it doesn't do anything a life form would be expected to do, it does behave very much like a pile of waste product, or at most, non living structural framework. We do know that the living things in kombucha are single celled. We also know the the SCOBY is non cellular, so very obviously the SCOBY itself is not alive. Whether it is made as a functional product (a living platform of sorts is the only likely possibility) or simply waste product is the only reasonable question.

Zapped 09-13-2012 02:46 PM

I don't dispute that you can grow a baby scoby with starter tea only (without adding a mother scoby to the brew) because the starter tea should have a mixture of yeast and bacteria. But I don't think you're correct about the scoby being a dead wast product. My understanding is that the bacteria in the scoby is very much alive, mixed in with the cellulose substrate that it is creating as it ingests the tea tannins and caffeine. I thought the bacteria also sorted themselves into anaerobic toward the bottom (submerged in the tea) and aerobic on the top (at the air/scoby interface).

Sdaji 09-14-2012 03:09 AM

There are live yeast and bacteria in the SCOBY, just as there are live people inside a bus or a building. Or maybe it's more like there are live pigs in a pig pen, and after a while a layer of $H!t builds up on the bottom and if you were too large to see an individual pig and picked up a big scoop of the $#!t you'd get some pigs with it, and perhaps think that the $#!t itself was self replicating. Buses and $#!t are still not living things, they are things created by living things, and on their own won't replicate. I really do think that by introducing the SCOBY to the new batch we're just dragging a bit of waste product along the way, or perhaps the equivalent of a burned out house which is no longer habitable.

The bacteria are facultative anaerobes. The same bacteria can switch between being aerobic and anaerobic or a bit of both at the same time depending on the conditions.

dschare 09-21-2012 01:10 AM

will it hurt anything if my scoby breaks?

porcupine73 09-21-2012 10:29 AM

Hi dcshare, the scoby will either repair itself if say it has a hole in it but it is still floating. If part of it sank, a new scoby will form. When the scoby is thin it is easily injured.


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