I was trained that you generally want to bung no more than .5 plato away from final gravity. We have a new head brewer and a beer that wont finish as low as desired. The beer needs to finish at 1.7 and he bunged it at 2.5, stalling at 2.2. He says you can bung it at even 6 plato and it will still finish. Is this accurate in anyone's experience/knowledge?
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Can you bung a fermenter too early ?
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Depends....
Spunding is a function not only of FG, but also head space; More head space = earlier spunding. Depending on yeast strain, they are somewhat inhibited by CO2 pressure. Not sure if only 1 bar pressure will impede your yeast. I wouldn't think it would matter much to the FG, but it may play with flavors a tad. It sounds like you have real-world experience with this recipe, tank, yeast, and procedure. If what you've done in the past works well, then I don't see any reason to play with it.Phillip Kelm--Palau Brewing Company Manager--
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I would agree with your new brewer. 0.5P to FG is a little close to final to catch, but if you have very little head space and pressurize to 15 psi you will capture a few bubbles.
I try to hit 65% attenuation to spund and apply 15 psi head pressure. When it is apparent that FG is reached, allow to sit an extra 24 hours to be sure - yeast is still cleaning up a few things. Start cold crashing slowly and apply head pressure to at least 15 psi as needed. If you are fermenting lagers, I set my diacetyl rest the day before I plan to cap off and let the temp rise naturally and finish off capped off with the spundvalve.
Back to the concerning issue. The loss of attenuation may be caused by a yeast shock from the change in procedure or more likely some thing else. I would start my experimenting with brewing two more batches, each with different cap off times. That would at least give you a set of data to compare. More importantly, look at the yeast generations, check to see if there is a change in yeast nutrients, calcium and zinc content, or mashing temp, calibrate all temp gauges and thermometers, check pH, check grist to water ratio. Many many variables to look at. Could also be grain if you have switched suppliers or if the base malt is of a new crop.Todd G Hicks
BeerDenizen Brewing Services
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Thanks for the reply
This is a new recipe for us, we are contracting it from a brewery using totally different water, cellar procedures, yeast, etc. Its a 60bbl into a 90, so plenty of head space so it couldn't have made too much pressure. I was just wondering if bunging early would effect the time it takes to attenuate, the research I've done doesn't seem to be conclusive. Just covering all my bases, like you said details details details.
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With that many different variables it's no wonder that you didn't get the same finishing gravity. For example my house yeast attenuates to 80+% pretty much all the time. If I switch to an American Ale yeast I have trouble getting the same recipe to 75% attenuation. In the past I've spunded the beer about a full point before terminal.
What is your starting gravity? Depending on your starting gravity you've only lost a couple percent attenuation, and a fraction of an alcohol point.
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We have had variable luck. Sometimes capping the fermenter seems to slow the fermentation - other times not. I think has to do with the yeast health in the first place.
The one thing I can definitely say is that storing yeast warm and under pressure is terrible for viability. Collect your yeast before closing the valve.
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Originally posted by kabrewku View PostWith that many different variables it's no wonder that you didn't get the same finishing gravity. For example my house yeast attenuates to 80+% pretty much all the time. If I switch to an American Ale yeast I have trouble getting the same recipe to 75% attenuation. In the past I've spunded the beer about a full point before terminal.
What is your starting gravity? Depending on your starting gravity you've only lost a couple percent attenuation, and a fraction of an alcohol point.
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