Monitoring fermentation progress - is this a crazy idea?

ncbrewer said:

I'm not sure I understand correctly. Are you saying that you took the gravity sample on brew day and you're leaving it in the test jar to monitor progress? If so, it won't tell you what's going on in the fermenter because of different conditions. Maybe I misunderstood?

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speedyvespa said:

Because I'm new, I want a way to monitor fermentation regularly as kind of a learning process. The books and web pages I've read all say that a common newbie mistake is to take too many samples and expose your patch to the risk of contamination. I can completely see why that's a common problem, if you're new, you're full of questions and enthusiasm.

The other thing I'm reading is to never think of the airlock and it's bubbles as a fermentation gauge, that's not what it's for.

What I decided to do was sanitise a test jar, draw a sample, plunk the hydrometer in there and cover it with cling wrap and a loosely-fitting elastic band to let Co2 escape. It's shown that on my brew day (Sunday), my wort was at about 1.050, and today it's around 1.031, which I think indicates things are going OK. It tastes like what i think it should, a flat IPA and a bit yeasty. To confirm, I drew a second sample from the bucket and it reads the same. I've now sealed it and it's going to stay that way until the hydrometer stops moving.

So - is having that sample drawn in a test jar with with a hydrometer a good idea, or is it flawed in some way?

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m_stodd said:

I like the idea, but don't know that I'd leave the hydrometer in it. Hydrometers are rather sensitive, so if some gunk clings to it after krausen, it will most likely be weighed down, and not be accurate. I'd just leave it out, and throw it in when you're curious.

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McCoy said:

As ncbrewer said, presumably your sample will have different fermentation conditions than the rest of your batch. At the very least it would be much more sensitive to the ambient temperature due to higher surface area to volume ratio.

It's not really majorly flawed in some way, but I'm kind of unclear why you're interested in doing this or what you hope to learn. My guess is that after some lag time, fermentation probably proceeds in such a way that the gravity drops roughly linearly in time with some kind of exponential tail as final gravity is approached. The rate of fermentation varies from strain to strain, but I think at most you could get probably get 16 points/day and at the low end (but still in the linear behavior regime) maybe 5 points/day. That's kind of a big range, but that's the kind of variability that comes with yeast strains. Either way, someone's probably already made those measurements.

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speedyvespa said:

I've looked up fermentation rate a lot and that's roughly in line with what I'm reading, but the nice thing here is that as new brewer, the more I read, observe and obsess it becomes less like machine code and more like a meaningful sentence of English One month ago, I wouldn't have understood your help here, but now I kind of do. Progress!

I think part of the appeal of closely monitoring here is because as I say, I'm not going off a recipe or a kit, I have no idea what OG should be, and in fact I've no way of determining IBU as the hops I were given (grown by a neighbour) are a mix of centennial and cascade and I don't know of what proportions. So I'm kind of regarding it as a single hop (what else can I do?) and the outcome could go either one of two ways

Problem is, if it's really good (and it's looking like it's not going to be bad) then I won't be able to make it again!

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Bensiff said:

Honestly, I wouldn't worry about it too much. But, you are learning and this is what helps you understand timelines of fermentation so have fun watching. I've been brewing for over a decade and still get a kick at seeing the yeast flocs moving around the currents during fermentation.

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speedyvespa said:

That's right, I'm the kind of person that gets into the science of anything and the how the minutiae explains the whole, so this kind of observation is part of the whole appeal of brewing for me.

To that point, my mother-in-law gave me a book on brewing from 1840 that her dad owned (her family has a long heritage of master brewers for various companies) and it talks about a 'theory' that a notable scholar had that yeast consists of 'animalcules' that are responsible for the brewing process via ingestion of the sugars - but the author of the book was resistant to this, arguing that it's a reactive process of two or more different compounds. I think the gentile early Victorians couldn't face the idea that beer is the result of tiny creatures eating the ingredients and farting it back out again. Possibly because of the marketing difficulties it could create!

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