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Thread: Any benefit/ drawback from gradually crashing temp?

  1. #1
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    Any benefit/ drawback from gradually crashing temp?

    Is there any reason to or not to gradually cold crash after diacetyl rest? Example 50 degs for a day, 40 for a day and 33 for a few? Or do people have better results going straight to 33? Thoughts ? Experiences? Thanks

  2. #2
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    Do you repitch your yeast?
    Joel Halbleib
    COO / Zymurgist
    Goodwood Brewing Co
    636 East Main St
    Louisville, KY
    goodwood.beer

  3. #3
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    For our lagers, we crash 2 degrees F per day during the week, 3 degrees F Mondays and Fridays, since no one does it over the weekend. It keeps the yeast healthy and happy for the next pitch. I haven't done any formal research, but I also assume that slowing down the crash also helps clean up whatever small amounts of diacetyl may be left after it can't be tasted.

  4. #4
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    Not repitching yet

  5. #5
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    Once the diacetyl rest is complete, generally the quicker you can remove the settled yeast, the better as there is less risk of autolysis, poor yeast viability and vitality if re-pitching, and off flavours from the autolysed yeast. 1 deg C / 2 F, seems to be a good rate of cooling - fast enough not to damage the yeast, or create ice on the chilling jackets, but fast enough to prevent autolysis during settlement, and fast enough to allow the yeast to settle rapidly not to get autolysis in the settled yeast, before sufficient has settled to make if worth / possible to remove the yeast sediment.
    dick

  6. #6
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    I see. So after d rest we went to 50 for a day and currently at 40 for another day and then 33 or so for a few more. Capped the blowoff/cip arm so it's all closed other thn the prv incase of something crazy. Kinda a related question now... once the cooling really settles out the remaining yeast/hops and we go to dump it what is the best way to account to the loss of volume in the fv? Opening the valve at the blowoff/cip would suck in unwanted o2 correct? Shoule we slowly push in co2 through the blowoff? Sorry guys 1st time with the unitank!

  7. #7
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    Do you have a pressure gauge on your blowoff/CIP arm? If there ends up being negative pressure in the tank you will suck air. We usually keep our tanks with a head of 5 psi once they are cold crashed and resting. We pressurize with CO2 through the CIP arm if we need to bump up the head pressure.

  8. #8
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    Preferred methodology, especially for wheat beers...

    Many, if not most, traditional wheat beer makers use a slower crash as matter of SOP. I've used a slower crash for beers for many years.

    You should also investigate spunding your tanks. Then there is no question of negative fermenter pressure. You will also obtain finer foam and less CO2 waste. Best of luck!
    Phillip Kelm--Palau Brewing Company Manager--

  9. #9
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    i was told by an old school brewer that doing the crash somewhat gradually- as in 2 to 3 days for ale, and maybe a week for a lager- would help the yeast be "put to sleep" in a slower, controlled manor that drove them to start doing whatever metabolic stuff they do to prepare for a "hibernation" and shut themselves down.

    obviously i dont have the scientific nomenclature down, but that was the general idea. i was told this was best practice when you intended on reusing your yeast over and over.

    but i never understood that in the context of the autolysis problem, did they wait until fermenation was totally done and they crashed before they pulled the yeast? sounds reasonable in theory but the more i think of it the more questions i have...

  10. #10
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    Also, if you have a way to program a controlled ramp-down of your temperature setpoint to the final temperature, you can spread out the cooling loads on your glycol system.
    Linus Hall
    Yazoo Brewing
    Nashville, TN
    [url]www.yazoobrew.com[/url]

  11. #11
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    With our Lager yeast we step it down slowly, 2-3 degrees a day. With our Ale yeast we go down to 50F for 24 hours then cash all the way (or slower if you have other tanks crashing to Linus's point). I have found over the years if you keep your crash schedule consistent your yeast strain will perform better then if you change it up for different batches. The yeast seems to get used to the schedule and vitality stays high. We repitch 10+ gens on our house ale. With our Lager we brew one beer and take it out around 20 gens.
    Just add co2 head pressure via the blow off arm to displace the slurry you drain off. Drain it slowly or you will blow a hole in the yeast slurry.
    Joel Halbleib
    COO / Zymurgist
    Goodwood Brewing Co
    636 East Main St
    Louisville, KY
    goodwood.beer

  12. #12
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    Re the last few posts - yes, I was only thinking of ale fermentations, not more traditional lager fermentations with slow cooling process to control diacetyl levels, this slow system often replaced by the big boys by using elevated temperature diacetyl rests, for shorter periods - hence lower capital requirements. A couple of the slow cool processes I used to brew with (yonks ago) have now been replaced with elevated temperature / shorter time rests.

    Lots of good points here.
    dick

  13. #13
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    We ended up doing 69 for 7 days (including rest) 1 day at 55, 1 day at 40, and 3 days at 35.. the stress on the chiller was def something we were considering. This being our 1st time with the system we were very surprised by the efficiency of the chilling rate (about 5 degrees an hour) but it is only 3 bbls. And yes pressure gauge on top and on cip/blowoff arm

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