Hops Fading Too Fast on IPAs

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philosofool

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That's exactly what the graph shows!

Since it's a log-linear graph (with the y-axis showing powers of 10), exponential decay is a straight line. Follow the yellow (15 psi) line, and after 10 cycles the remaining 02 has dropped by a factor of 1000 ~ 2^10.
Hah! Looks like I'm totally paying attention...

Anyway... for those following along at home, it is more CO2 efficient to purge more times at lower pressure. The general form of the equation is

80*(x/(x+atmos))^n * V= ppm O2

Where atmos is atmospheric pressure (11 where I live, 14 for most) and x is the regulator psi and n is number of purges. V is volume headspace in liters. This assumes a 5 gallon keg.
 

hobomoto

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Whilst this might stand to reason for flavour it doesn't regarding aroma. If aroma is it good when yeast is in suspension the the hop oils must be free from the cell walls of the yeast in order to be volatile and contribute aroma.
I agree, I still think his issue is oxygenation... He clearly stated he was only doing two purge cycles at an unknown psi. That would leave quite a bit of packaged o2. I think yeast dropping out of solution with bound hop compounds reduces hoppiness but doesn't turn it into a "complete dud" as the OP said his beer turned into... lots of people dry hop before fermentation is even complete now-a-days and get great dry hop character. From what I understand the yeast/hop binding effect can be overcome with more hops... oxygenation not so much.

Water chem? His beer was good then it got bad. If it was a water chem issue I would think it never would have been good in the first place, right? I don't know that much regarding water chem but that seems logical to me.
 

beerkench

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I agree, I still think his issue is oxygenation... He clearly stated he was only doing two purge cycles at an unknown psi. That would leave quite a bit of packaged o2. I think yeast dropping out of solution with bound hop compounds reduces hoppiness but doesn't turn it into a "complete dud" as the OP said his beer turned into... lots of people dry hop before fermentation is even complete now-a-days and get great dry hop character. From what I understand the yeast/hop binding effect can be overcome with more hops... oxygenation not so much.

Water chem? His beer was good then it got bad. If it was a water chem issue I would think it never would have been good in the first place, right? I don't know that much regarding water chem but that seems logical to me.
I really don't think it's oxidation. Too many are too quick to blame oxidation on here.
 

Queequeg

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Well the thing is hoppy beers are extremely sensitive to oxidation and only small amounts of air can cause significant oxidation and only 0.1ppm is required for hop deminishment
 

madcowbrewing

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Instead of transferring to secondary, couldn't you drop the temp after your primary to drop out the yeast cells before you dry hop?

Or does this not drop out enough cells like in a keg?
 
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