Largest temp adjust interval without shocking/stressing yeast

[marshall_tucker]

I feel very certain this topic has been discussed, but to my astonishment google is not really yielding any results. if anyone knows of a link, i humbly apologize in advance. One instance where i kinda/sorta found an answer is here, 2nd question down, maybe you guys will have commentary on it: http://morebeer.com/brewingtechniques/library/backissues/issue4.2/miller.html

anyway, the question...i am currently fermenting my first lager (which may end up being a zwickelbier more or less per a recent thread) and i am planning out my temperature schedule for the D rest. i realized "wow, going from 50 to 67 degrees is a big jump. perhaps this increase needs to be done in steps to avoid stressing the yeast." which lead me to this...exactly how much can one adjust (increase) the temp per day without having negative effects on the yeast? (however subjective the word "negative" may be, i'm just using it in a broad sense). Do different strains have different tolerance to temp swings? (i'm using W34/70)

I know many people have mentioned gradually changing the temp in prep for the rest, but i never recall seeing discussion on the actual per-day break down of temp interval change.

considering 5 gallons is a big thermal mass, i realize there is some fudge factor, but still there must be a line somewhere on this subject.



As a sidenote, i noticed varying opinions when people claimed that yeast tolerates (cold -> hot) much better than (hot -> cold). never realized that was a possibility, i figured it was all relative.

 

[giraffe]

As a rule, I usually up the temp 5 degrees a day. That is certainly safe.

Ive also when needing the cold conditioning space, took the beer out at 48, and put it in a basement that stays in the mid 60s for the diacetyl rest. I honestly couldnt tell the difference, it worked fine, and the beers done that way were clean. Its obviously not best practice, but ive done it a dozen times and it seems to have no effect on the beer I can detect.

 

[Hujo]

If you're using a "normal" fridge as a fermentation chamber, you can't shock or stress the yeast by changing the temperature. The relatively large thermal mass compared to the space and cooling/warming ability of a domestic fridge/freezer slows the change down enough so no harm can be done. Unless you're using some kind of monster heating element, you'll be fine. I never ramp anymore, the beer does it for me.

 

[marshall_tucker]

sounds good, thanks guys.

i probably could have just let it rise naturally (i'm not using any device for raising temperature btw) but i guess the overly-methodical side of me prefers to have some control over it, i was afraid it would either rise too soon (which probably wouldn't hurt per se but i figured longer time spent in the 50's, the better) or wouldn't rise soon enough on demand (okay so i could use a heating device if necessary)

water over the dam at this point though, but i'll certainly reconsider my process next time

 

[SpeedYellow]

I've never seen or heard any claim that warming the yeast too quickly causes any issues. Why would it? I regularly just crank my t-stat up 15F for d-rests, which turns on 2 heat belts on my fermenter, causing a pretty quick warming. The yeast don't care. But if you feel better ramping up the temp slowly, then do it, just don't kid yourself that there's some basis.

Now, cooling the temps quickly is another question altogether...

 

[Buckeye_Phil]

I agree with other posters. Letting temp free rise is my preferred method for d-rest. I have a dual function temp controller. So I'll start my ferment with heating and cooling set to 50degF. Once I'm ready for d-rest, I'll crank cooling set point up to 60, but leave heating set at 50. This way the yeast is doing the work and the heating element doesn't kick on. If it needs some help getting to 60 after a few days, I'll set the heating control to ramp the last little bit. But it's never been a problem.

One thing to consider is - you're trying to get the yeast to ramp up activity at the end of a ferment to clean up off flavors. If you gradually increase fridge temp, the yeast will warm slightly and then cool down when the fridge kicks on. At the end of the ferment, these up/down swings may not be the best for promoting yeast activity. In my experience, the first hint of a cold crash sends the yeast to sleep. Anyway... That's how I justify the natural ramp approach.

 

[SpeedYellow]

Just remember, if it takes 2 days for the beer to get up to your target d-rest temp, that's 2 more days that you have to wait to drink the beer. Since there's no basis for a slow ramp up, there's no way I'll give up 2 days to that speculation.