Author Topic: pitching on a yeast cake  (Read 2373 times)

Offline majorvices

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Re: pitching on a yeast cake
« Reply #15 on: March 19, 2013, 08:08:38 AM »
High temperatures early in the fermentation tend to increase fusels. Ester formation is caused by different factors and vary from strain to strain.

I think some brewers tend to get fusels and esters mixed up. Fusels taste more like rubbing alcohol, nail polish, etc and tend to kill head retention and cause head aches.

For the most part if you ferment under 72 with most ale strains you will minimize ester development.
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Offline denny

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Re: pitching on a yeast cake
« Reply #16 on: March 19, 2013, 10:17:26 AM »
A snippet from the Danstar page:

"High temperature early in fermentation decreases ester production. High temperature later in fermentation increases ester production"

This is the opposite of what I've always thought. Can some explain the reasoning behind this?

All I can say is that's the opposite of my experience.
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Offline a10t2

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Re: pitching on a yeast cake
« Reply #17 on: March 19, 2013, 11:33:34 AM »
I could come up with a plausible hypothesis for the first statement. Minimal ester production is occurring during the log growth phase, and increasing the metabolic rate could yield a little higher cell count and therefore lower esters.

The second part I don't understand. I guess if there are a lot of fusels you'd accelerate the redox reaction (I can never remember which way it goes) converting them to esters, but that seems oddly specific.
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Offline majorvices

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pitching on a yeast cake
« Reply #18 on: March 20, 2013, 06:06:30 AM »
But it's still going to vary fr strain to strain. For instance, wy1056 will generate very little esters even as high as 72-74 degrees while a hefe wiezen strain will through all kinds of esters at 62. Increasing pressure on Some strains lowers the ester profile significantly. Pitching rates affect ester profile a heck of a lot (I've seen some studies that shows under pitching decreases esters with many strains over over pitching increases esters).

Regardless, pitching cool is going to reduce the amount of fusels and those you definitely want to keep as low as possible. Pitch and start out cool and you will have a cleaner tasting beer. As long as you stick to a decent pitching rate and don't go crazy with the temp your ester profile will fall nicely into place. You may want to experiential with different temps, aeration times and pitching rates to find the profile you are looking for.
Keith Y.
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