Scoby Dark Brown on Top

[Michael Peter – RBC CEO]

This photo was sent in by email from one of our favorite customers who has started a small cottage brewing business for family and friends out of her home during pandemic:

Customer’s Email:

Should I stop using it? Peel off the top layers? Probably 2 months old.  Tastes different than any of my previous batches.  It’s in my continuous brew so I’ve just been leaving them in. It’s 2.5gallon container. I harvest 1 gallon then replace with fresh tea. The tea itself isn’t 2 months, I harvest every 5 days. But have been leaving the scoby in there…tastes different than what I harvested last week, and not in a good way.  Not like gross, just different. The growing dark spots just scare me…Just wasn’t sure if I should get rid of the whole thing or just like peel it in half and get rid of the top part.  Please Help!!!

Our Repsonse:

You said it didn’t taste good….for that reason alone, you should throw it out and sanitize the jar.  Simple reason being: irrespective of what it is and whether it should be there, why continue to grow something you don’t particularly love, that could very well end up infecting the rest of your jars?  There’s always the possibility that it could be stronger or overfermented, and you just don’t enjoy it as much.  Simple way to assess that: was what didn’t taste good the same age as what did taste good?  If so, absolutely throw it out.

That being said, this scoby doesn’t look bad to us…it does look dry and old.  I’m sure there are some people that have had their continuous brewing systems going for years, but in our opinion, it’s not ideal.  Continuous brew systems shouldn’t go forever — they change over time.  Have you ever had a culture that starts off producing white scobies, or very close to it, and after a bunch of generations it starts to get darker.  We can’t prove this (yet) but our hypothesis is that, over time, other organisms (bacteria and yeast) become a symbiotic part of the culture — they’re everywhere, it happens.  And while these (also symbiotic) bacteria and yeast may not be enough to “ruin” the culture, they can certainly be enough to change and produce off flavors.

We can’t prove this yet either, but in our brewery a healthy scoby is basically white or very light cream color. The darker, the less healthy….be it from dryness or symbiotic infection.  We sanitize and start fresh when we start to see color or taste flavor changes we don’t like.

Our suggestion: you don’t need to pull scobys from your continuous brews every time, but maybe try a little more often.  And start fresh when you see or taste ANYTHING you don’t like.  Also, keep in mind putting your hands in your brew is a big vector for infection, even when they were just washed.  Use utensils (tongs) instead.

Also, you had said before you weren’t using one of our scobys…you might contemplate ordering a scoby from us. Not all scobys created equal.

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