Author Topic: A bunch of questions on harvesting yeast  (Read 1021 times)

Offline Saccharomyces

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Re: A bunch of questions on harvesting yeast
« Reply #30 on: November 18, 2020, 11:23:10 PM »
However, O2 pickup is a non-sequitur while yeast cells are still in suspension. One of the reasons why bottle-conditioned beer stores better than filtered and bottled beer is because bottle-conditioned beer has an active yeast culture that continues to scrub O2 as long as it is in suspension.

Offline BrewBama

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A bunch of questions on harvesting yeast
« Reply #31 on: November 18, 2020, 11:37:15 PM »
However, O2 pickup is a non-sequitur while yeast cells are still in suspension. One of the reasons why bottle-conditioned beer stores better than filtered and bottled beer is because bottle-conditioned beer has an active yeast culture that continues to scrub O2 as long as it is in suspension.
I thought the yeast had to be active. Thx for the clarification. Good to know it just has to be present.

I recall Dr Bamforth saying if a beer is oxidized run some yeast thru it. If you say it doesn’t have to be active his statement makes even more sense.
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Offline erockrph

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Re: A bunch of questions on harvesting yeast
« Reply #32 on: November 19, 2020, 03:38:22 AM »
As far as CO2 coming out of solution, are you referring to airloc activity in general or something more specific? My understanding is that changes in air pressure and/or ambient temp changes can affect airloc activity even when no fermentation is happening. Maybe there is more to that?

I am attempting to differentiate between dissolved CO2 coming out of suspension and CO2 actually being produced.  The beauty of using a clear fermentation vessel is that it is easy to determine when fermentation is complete because there is a color change, starting at the top, when fermentation is complete. The thing to remember is just because a batch has reached terminal gravity does not mean the yeast culture is done doing its job.  Most cultures will continue to consume metabolic waste products for a period of time after it appears that fermentation is complete.  That is why cold crashing as a practice is non-optimal for amateur brewers who have the gift of time.  I have never had a cold-crashed beer that tasted as good as one that was allowed to settle on its own schedule.  Amateur brewers do not need to cold crash because we are not beholden to bean counters. Our hobby is not driven by profit and loss.
I have a few recent brews that seem to corroborate this statement. I ferment in kegs with a spunding valve on the gas poppet. My last few batches have been chilled and kegged as soon as there was no increase in pressure on the valve for at least 2 days, rather than waiting my usual 10-14 days to package. I'm finding that these batches taste more muddled and flat than usual.

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