I brewed the Deschutes Porter 3 weeks ago. When racking I observed one glass carboy was 1.013 and the other 1.018. I usually see a difference, but never this much. I figure it has to do with the yeast. Used Wyeast 1968 - Began with a 1300 ml starter on stir plate - 24 hours then moved to a 5000 ml flask and added another 1300 ml sanitized wort to make a total of 2600 ml of starter. The wort started out at 1.058 into both carboys - same temps each. I aerated each with O2 for 1.5 minutes each then shook the yeast starter and dumped 1/2 into the one carboy and the rest into the other. Both carboys sat in a temp. controlled water bath at 62 - 64 degrees F for two weeks - shaking every couple days - then a 24 temp raise to 70 degrees. Then back down to 62 - 64 for the remainder of the three weeks since brewed. I think one carboy must have got a bit more yeast then the other. ??? (Good reason to spring for a larger conical fermenter one day!)
Joined: 12 Dec 2010 Posts: 10600 Location: Ottawa, Canada
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Link Posted: Sat Jan 20, 2018 6:36 pm Post subject:
Something's definitely different. Could be that you measured the gravity differently? Or possibly incorrectly? Was the wort temperature stable?
Or like you said, that one got a lot more yeast than the other. Fairly probable given how flocculant 1968 is. It settles out almost immediately so maybe the first fermenter actually got very little. Do you happen to know which fermenter got the first pour? I would suspect it was the one that finished higher.
Though that said, they still should have ended up at roughly the same place if allowed to ferment to completion, the one with less yeast would simply have taken longer to get up to speed and possibly through a few more off-flavours from the stress of reproducing. Sometimes underpitching can however result in less attenuation too but usually things have to go wrong for this to happen or you have to really severely underpitch.
If I'm splitting into 2 fermenters, here's what I do:
1. Make the yeast starter in a large 5L flask.
2. When the starter fermentation is done, pour it into two 2L flasks evenly (it should still all be stirred up, i.e. split it immediately after turning off the stir plate).
3. Place the two 2L flasks in a fridge for ~24-48 hours and the yeast will settle out completely. (1968 is so flocculant it probably would settle out in only a few hours).
4. When ready to pitch, decant the wort/beer (dump it) down the drain), and pitch only the yeast. I usually put a cup or two of the new wort into the flask and swirl. 1968 is chunky so you need to be vigorous. Just make sure to get all the yeast into the fermenters.
The amounts of yeast should be very even if done this way.
Link Posted: Sat Jan 20, 2018 11:27 pm Post subject:
Yea - I think it had to be yeast amount - related. I've never liked splitting the yeast into two fermenters, but until I get a larger conical - that's the SOP. I'll have to try splitting the yeast into two 2000ml flasks and refrigerating. - But, I shook the 5000ml well before pouring off 1/2 - so "should have been as close". I think the one that finished lower was the first yeast pour... I might just keg that carboy first and let the other sit to see what happens. And yes - 1968 settles FAST - hope there's enough left to take it on down. In any case it's tasty - just a bit sweeter. Thanks
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