Author Topic: factors contributing to diacytel  (Read 1536 times)

Offline hokerer

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Re: factors contributing to diacytel
« Reply #15 on: July 10, 2011, 12:40:36 PM »
Also, i notice it says raising the temperature to around 65, which is way lower than i can achieve in the hot Denver summers. The lowest i can get is 72. What sort of techniques to you all use to lower fermentation temperature in the summer?

72 is still way too high.  Go out and get one of those half barrel plastic tub thingies that they put kids toys in.  Put your fermenter in that and then fill the tub with water.  Drop a couple frozen water bottles into the water to keep things cool.  Replace the water bottles as necessary.
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Offline tom

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Re: factors contributing to diacytel
« Reply #16 on: July 10, 2011, 02:39:01 PM »
A water bath is surprisingly efficient.  You can use a sink, tub, etc.

The 65F is for lagers.  A diacetyl rest for ales is usualyl just letting it sit for another day or 2 after it has reached its final gravity.
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Offline bluesman

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Re: factors contributing to diacytel
« Reply #17 on: July 10, 2011, 02:41:21 PM »
JZ says that a higher ferm temp produces more of the precursers that are responsible for diacetyl formation and visa versa. Therefore he recommends pitching low to supress the precursers and ultimately produce a beer with miminal diacetyl.

For pitching low, what sort of temperatures are we talking about?

Also, i notice it says raising the temperature to around 65, which is way lower than i can achieve in the hot Denver summers. The lowest i can get is 72. What sort of techniques to you all use to lower fermentation temperature in the summer?

Like Denny, I also pitch my ales in the low to mid 60's as a general rule and for lagers I like to pitch in the mid 40's.

You will need to establish some type of fermentation control in order to make really good beer. I use a chest freezer that was modified using a collar and a digital controller. I can keep the fermentation at setpoint +/-1 degree. So I'll pitch at 64F and set the controller for 67F.

You can also consider using a swamp cooler which is basically a large plastic bucket filled with water maintained at fermentation temp using ice. Wet towels can be wrapped around the upper portion of the fermenter and a fan can also be used to help the heat transfer process.
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Offline astrivian

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Re: factors contributing to diacytel
« Reply #18 on: July 10, 2011, 09:15:02 PM »
Thanks for the tips. I have to be careful though: This hobby has to remain spouse-approved. For at least July and August, 70 will have to be my temp.

Going back to the diacetyl though, I just got my copy of the 3rd ed of How to Brew.

Quote
"...to hot (more than 10 degrees above the nominal range) and they [yeast] indulge in an orgy of fermentation, creating excessive by-products that often ruin the flavor of the beer. High temperatures can lead to excessive levels of diacetyl."
(pp. 86-7)

Thinking back, I did this recipe twice very successfully, BUT i brewed it much earlier in the year, like May. There is a huge difference in ambient temperature between May and July in Colorado. In other words, i got lucky before and didn't know why. You are right on bluesman, i need to get a grasp of fermentation temp to do anything consistent. I dabbled for a while and now i am getting serious.
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Offline a10t2

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Re: factors contributing to diacytel
« Reply #19 on: July 11, 2011, 08:27:46 AM »
There is a huge difference in ambient temperature between May and July in Colorado.

YOUR part of Colorado, maybe. ;D

But yes, consistency during fermentation (pitching rate and temperatures) is the number one thing most people can do to improve their beers. I think a swamp cooler is totally adequate for most home brewers' needs. Once you've calibrated it to your conditions, you can achieve very consistent results on a spouse-friendly budget.

http://seanterrill.com/2009/05/20/regulating-fermentation-temperatures/
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Offline jklinck

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Re: factors contributing to diacytel
« Reply #20 on: July 17, 2011, 02:55:53 AM »
JZ says that a higher ferm temp produces more of the precursers that are responsible for diacetyl formation and visa versa. Therefore he recommends pitching low to supress the precursers and ultimately produce a beer with miminal diacetyl.

For pitching low, what sort of temperatures are we talking about?

Also, i notice it says raising the temperature to around 65, which is way lower than i can achieve in the hot Denver summers. The lowest i can get is 72. What sort of techniques to you all use to lower fermentation temperature in the summer?

Recirculate ice water through your wort chiller with a pond pump. Then it doesn't matter what your ground water temps are. Chill normally for 10 min and then switch. I can get my lager worts down 42F with this method.
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