*Ss Brewing Technologies Giveaway - Enter Now!*

Home Brew Forums > Home Brewing Beer > Brew Science > Cell membranes and temperature fluctuations
Reply
 
LinkBack Thread Tools
Old 01-16-2013, 01:59 AM   #11
Delaney
Feedback Score: 0 reviews
Recipes 
 
Join Date: Jul 2011
Location: Montreal, Quebec
Posts: 490
Liked 14 Times on 14 Posts
Likes Given: 15

Default

Quote:
Originally Posted by Wynne-R View Post
Can somebody define this range?
This is specific to the strain of yeast you are using...In other words, there will be different temperature ranges for different strains. Therefore it is important to respect the range provided by the yeast supplier.

For example, lager yeasts require cold temperatures, whereas ale yeasts require warmer temperatures. It is more specific than this, however. Different ale yeasts will have different temperature ranges.

Quote:
Originally Posted by Curtis2010 View Post
Important to keep in mind relative to ferm temps that all those hordes of feeding yeasty beasties generate a lot of heat. I've checked temp on ferms and found the wort temp 10F higher than the ambient temp. So, it would be easy to set ambient temp within range for the yeast strain and have the heat of ferm push the wort temp beyond that range -- possibly resulting in off flavors.

Your post also confirms that even for ale yeast the lower end of their temp range produces fewer off flavors. I've suspected this was ture, and am planning to start fermenting ales at the lower end of their temp ranges. I expect this is especially important during early very active fermentation when yeast activity produces heat.

Thanks.
Yes, this is important to note. The temperature range of a yeast does not refer to the ambient temperature. Fermentation generates heat, therefore one must pay attention to the temperature of the beer/wine, and not the room temperature.


From what I understand, it is more beneficial to ferment at lower temps because this will result in less volatile compounds (aromatic/flavor) from evaporating. As long as you do not exceed the temperature range for the yeast in question, I do not believe that off flavors would be produced. It would taste different, however, because you would have evaporated volatile compounds that would not have been lost at lower temperatures. Unless you have precise temperature regulation, you would probably want to stick to the lower end, in the event that temperature might fluctuate and go beyond the acceptable range.
There are always exceptions to these rules, as Dr.Merwe pointed out...for example one wants autolysis to occur, to a limited extent, in sparkling wines. Perhaps some beers would fare better without some of these volatile compounds?


PS: what part of Guate you at? I spent 6 months travelling throughout the land of eternal spring. What a beautiful place. Got kinda tired of Gallo though .

Quote:
Originally Posted by tgmartin000 View Post
What's considered a "fluctuation"? From what I understand, both the rate and magnitude of the temp swing is what matters. For instance, a swing up of 5 degrees in five days may be beneficial, whereas five degrees in five hours is probably pretty bad.

A fluctuation means a change in temperature...I would not be worried about the rate of temperate fluctuations, unless you are fermenting a small amount of beer (1 gallon). Large volumes of beer (5 gallons +) have a greater mass, therefore it requires much more heat to raise/lower the temperature of the liquid. Perhaps a very fast rate of temperature fluctuation would temporarily inhibit the biological functions of yeast cells, but I believe this would require a drastic difference between ambient and solution temperature.

As far as I'm aware temperature swings are not going to be beneficial. If the fluctuation is within the yeast's tolerable temperature range, however, it won't be detrimental, other than perhaps losing some of the more volatile compounds at higher temps.
__________________
Delaney is offline
 
Reply With Quote Quick reply to this message
Old 01-17-2013, 02:41 PM   #12
Curtis2010
HBT_SUPPORTER.png
Feedback Score: 0 reviews
 
Curtis2010's Avatar
Recipes 
 
Join Date: Dec 2011
Location: , Guatemala
Posts: 985
Liked 73 Times on 51 Posts
Likes Given: 1

Default

Quote:
Originally Posted by Delaney View Post
This is specific to the strain of yeast you are using...In other words, there will be different temperature ranges for different strains. ...

Yes, this is important to note. The temperature range of a yeast does not refer to the ambient temperature. Fermentation generates heat, therefore one must pay attention to the temperature of the beer/wine, and not the room temperature.


From what I understand, it is more beneficial to ferment at lower temps because this will result in less volatile compounds (aromatic/flavor) from evaporating. As long as you do not exceed the temperature range for the yeast in question, I do not believe that off flavors would be produced. ......

PS: what part of Guate you at? I spent 6 months travelling throughout the land of eternal spring. What a beautiful place. Got kinda tired of Gallo though .
...

Yes, Guate is a beautiful country. I live on the Rio Dulce which is on the Caribbean coast, so temperature control for brewing is a necessity (the highlands would probably be ideal for brewing). Too warm here on the Rio even to brew ales in the "winter" (now). It's not quite 9AM yet, and the ambient temp is 75F (pleasantly cool for here, YTD low= 71F, high = 92F). I use a couple of chest freezers with external thermostats for fermenting and a mix of corny kegs and carboys are fermentors.

So, based upon my past experience and this discussion here is what I plan to do for future ale ferm temps. I bank US-05 and use it for most general ale brewing so I'm assuming US-05. Temp ranges for US-05 per Fermentis are 12-25°C (53.6-77°F) ideally 15-22°C (59-71.6°F). By "ambient temp" in this context I mean the temp inside the cooler.

1. Chill wort to 75F and pitch yeast. (This a challenge to do here since my "cooling" water is about 80F, but I have a pre-chiller on the drawing board).

2. Set cooler thermostat to 54 and move fermentor to cooler. (My thought process here is that by the time ferm is active then the wort should be at or near ambient temp and if ferm activity increases wort temp by even as much as 10F then wort will still only be at 64F which is right in the "ideal" range.)

3. As very active primary fermentation subsides, gradually (2F per day) raise ambient temp to 60F and leave it there for the duration of fermentation (as determined by SG readings). I think that even less active ferm will raise the temp a few degrees so ambient of 60F should keep wort within ideal range without risking getting it too cool.

I plan to check wort temps along the way to confirm this strategy works.


Sound like a good plan?
__________________
Curtis2010 is offline
 
Reply With Quote Quick reply to this message
Old 01-17-2013, 05:10 PM   #13
Wynne-R
Feedback Score: 0 reviews
Recipes 
 
Join Date: Aug 2009
Location: Texas
Posts: 897
Liked 96 Times on 62 Posts
Likes Given: 76

Default

In the book “Yeast” Chris White and Jamil Zainasheff suggest pitching a couple of degrees below your target and letting it drift up to the target temp over 18 - 36 hours. Hold it steady until the fermentation is 2/3 - 3/4 done, then increase it 4-10F over the course of a day or two.

Their rationale is that the flavor compounds are mostly done, but increasing the yeast metabolism will allow them reduce intermediary compounds and attenuate more fully.

So in the case of US-05, we could start at 62°F, let it increase to 64, hold it for a couple of days and then ramp it up to 70°F. Hold it there until you think it’s done.

My interest is in how tight the optimum temperature regulation should be. In my experience ± 1°F is better than ± 3°F. This is actual wort temperature, measured with a thermowell.

__________________
Wynne-R is offline
 
Reply With Quote Quick reply to this message
Old 01-17-2013, 05:22 PM   #14
Delaney
Feedback Score: 0 reviews
Recipes 
 
Join Date: Jul 2011
Location: Montreal, Quebec
Posts: 490
Liked 14 Times on 14 Posts
Likes Given: 15

Default

Quote:
Originally Posted by Curtis2010 View Post
Yes, Guate is a beautiful country. I live on the Rio Dulce which is on the Caribbean coast, so temperature control for brewing is a necessity (the highlands would probably be ideal for brewing). Too warm here on the Rio even to brew ales in the "winter" (now). It's not quite 9AM yet, and the ambient temp is 75F (pleasantly cool for here, YTD low= 71F, high = 92F). I use a couple of chest freezers with external thermostats for fermenting and a mix of corny kegs and carboys are fermentors.

So, based upon my past experience and this discussion here is what I plan to do for future ale ferm temps. I bank US-05 and use it for most general ale brewing so I'm assuming US-05. Temp ranges for US-05 per Fermentis are 12-25°C (53.6-77°F) ideally 15-22°C (59-71.6°F). By "ambient temp" in this context I mean the temp inside the cooler.

1. Chill wort to 75F and pitch yeast. (This a challenge to do here since my "cooling" water is about 80F, but I have a pre-chiller on the drawing board).

2. Set cooler thermostat to 54 and move fermentor to cooler. (My thought process here is that by the time ferm is active then the wort should be at or near ambient temp and if ferm activity increases wort temp by even as much as 10F then wort will still only be at 64F which is right in the "ideal" range.)

3. As very active primary fermentation subsides, gradually (2F per day) raise ambient temp to 60F and leave it there for the duration of fermentation (as determined by SG readings). I think that even less active ferm will raise the temp a few degrees so ambient of 60F should keep wort within ideal range without risking getting it too cool.

I plan to check wort temps along the way to confirm this strategy works.


Sound like a good plan?
The only way to know for sure is to try it and see what ferm temps you get with that system...

That being said, depending on the volume you are fermenting, I suspect that the process of cooling in your system would be relatively slow. The greater the difference in temperature between your solution (wort) and the surroundings, the faster it cools. Inversely, the less of a difference between these temperatures, the slower it cools. The difference in temperature you are mentioning is not great, therefore I'd assume it would be a slow process to cool the wort from 75F.

Furthermore, if you pitch at a good ratio, active fermentation can start very quickly..it would likely raise the temp of your wort by at least 5F. So in my opinion, you risk having your wort exceed the tolerable temperature range for your yeast, causing heat stress.


Perhaps you should investigate other yeast strains for ales which are tolerant of slightler higher temperatures given your predicament? Again, you will have to experiment and carefully monitory the temperature of your wort/beer to be certain.



PS: I've been to Rio Dulce. A friend of mine owns some forest along the coast between there and livingston. We went out there in one of those ghetto taxi boats and got smashed on coco loco. Good times, hot as hell out there and not much infrastructure, so I can definitely relate to the difficulties you'd face.
__________________
Delaney is offline
 
Reply With Quote Quick reply to this message
Old 01-17-2013, 05:31 PM   #15
Delaney
Feedback Score: 0 reviews
Recipes 
 
Join Date: Jul 2011
Location: Montreal, Quebec
Posts: 490
Liked 14 Times on 14 Posts
Likes Given: 15

Default

Quote:
Originally Posted by Wynne-R View Post
In the book “Yeast” Chris White and Jamil Zainasheff suggest pitching a couple of degrees below your target and letting it drift up to the target temp over 18 - 36 hours. Hold it steady until the fermentation is 2/3 - 3/4 done, then increase it 4-10F over the course of a day or two.

Their rationale is that the flavor compounds are mostly done, but increasing the yeast metabolism will allow them reduce intermediary compounds and attenuate more fully.

So in the case of US-05, we could start at 62°F, let it increase to 64, hold it for a couple of days and then ramp it up to 70°F. Hold it there until you think it’s done.

My interest is in how tight the optimum temperature regulation should be. In my experience ± 1°F is better than ± 3°F. This is actual wort temperature, measured with a thermowell.
Interesting. I'd imagine that some of the most volatile compounds would still be lost as a result of raising the temp to 70F, but this would also likely be minimized due to a less active fermentation. This logic seems reasonable.

I don't understand what you mean by the optimum temperature. The optimum temperature for a given yeast strain is anything within the range for that species...I'd imagine that you would achieve different results at different temperatures within that range, so "optimum" temperature would really depend upon what you are striving for...

Intuitively I'd imagine that minimizing the fluctuations in temperature would produce a more specific flavor, whereas greater fluctuations would provide a slightly broader range of compounds. Is one better than the other? Depends what you want...I also imagine that the degree of variance would depend on the strain in question. For example, pseudo-lager strains produce a lager-like flavor at the lower end of their range and more of an ale-like flavor at the higher end. This would be an example of high variance within the range of tolerable temperatures....whereas other strains might display less variance.
__________________
Delaney is offline
 
Reply With Quote Quick reply to this message
Old 01-17-2013, 05:58 PM   #16
Kaiser
Feedback Score: 0 reviews
 
Kaiser's Avatar
Recipes 
 
Join Date: Nov 2005
Location: Pepperell, MA
Posts: 3,904
Liked 114 Times on 71 Posts
Likes Given: 4

Default

Quote:
Originally Posted by Wynne-R View Post
My interest is in how tight the optimum temperature regulation should be. In my experience ± 1°F is better than ± 3°F. This is actual wort temperature, measured with a thermowell.
+/-1 is better than +/-3 IMO.

It's important how this temperature is measured. If its measured with a thermowell you can set a fairly small band (+/-1, for example) if it’s the ambient temperature of the fermentation room you want a broader band to prevent your cooling compressor from cycling too frequently.

Note that there is nothing wrong with controlling the ambient temperature as long as it is chosen such that the fermentation temp peaks at the desired temp. There is also nothing wrong with temp swings in the ambient temp since the thermal mass of the beer will even them out.

I, for example, set my freezer chest to 6.5 C when brewing lagers. The fermentation activity will raise the temp to ~8.0 C. When I then see the beer temp fall again I know fermentation slows down and I can raise the ambient temp.

Kai
Kaiser is offline
 
Reply With Quote Quick reply to this message
Old 01-17-2013, 07:26 PM   #17
Wynne-R
Feedback Score: 0 reviews
Recipes 
 
Join Date: Aug 2009
Location: Texas
Posts: 897
Liked 96 Times on 62 Posts
Likes Given: 76

Default

I am regulating the temperature of a six gallon water bath that a 5 gal carboy is setting in. For years I did this by adding ½ liter water bottles to the bath. Recently I figured out how to automate the process with a controller. It does a good job of regulating the water ± .3°C. That translates into ± .1°C in the beer, measured with a thermowell.

There are some vagaries in the process of regulating the water temperature with overshoot, stratification and circulation, but that probably works in my favor.

Interesting that Delaney mentioned “ a more specific flavor, whereas greater fluctuations would provide a slightly broader range of compounds.”
It’s hard to describe a flavor,but that’s a pretty good description of what I’m finding.

Oh, and I guess you figured it out, but I said ‘optimum temperature regulation’ not optimum temperature. It’s interesting, based on your comment that in some circumstance it might be advisable to increase the differential. Seems counterintuitive.

More research is required.

__________________
Wynne-R is offline
 
Reply With Quote Quick reply to this message
Old 01-17-2013, 08:41 PM   #18
Delaney
Feedback Score: 0 reviews
Recipes 
 
Join Date: Jul 2011
Location: Montreal, Quebec
Posts: 490
Liked 14 Times on 14 Posts
Likes Given: 15

Default

Quote:
Originally Posted by Wynne-R View Post
More research is required.
Maybe this is just symantics but I'd call it experimentation not research. No matter how much research is done, I imagine that optimal temperature regulation would vary between yeast strains, styles of beer, and individual recipes. Perfection would require experimentation regardless, unless it is a proven recipe.

This is getting pretty nit-picky though...I imagine that in the context of homebrewing, many of us would probably have a hard time discerning the difference between a beer produced with temperature regulation ± .3°C vs. ± .1°C. Perhaps I'm wrong, just my guess. Either way, this is all good food for thought..for me at least.
__________________
Delaney is offline
 
Reply With Quote Quick reply to this message
Old 01-17-2013, 10:09 PM   #19
Hermit
Feedback Score: 0 reviews
Recipes 
 
Join Date: Nov 2009
Location: Alternate Universe
Posts: 2,246
Liked 67 Times on 57 Posts
Likes Given: 10

Default

I have some aluminum tape and used that to fix my probe to a little piece of insulation. It is only about a quarter inch thick. The silver looking stuff that made to go around heat ducts and you see people wrapping kettles in. I put the aluminum tape side against the fermenter and have a strap that cinches it on pretty tight against the glass carboy. Typically I'll set my controller 5F lower than what I want. My FG sample sits close by with the hydrometer still in it and I start adjusting up depending on what that is doing. The sample is usually warmer than the fermenter so it will go faster anyhow. Short of a thermal well it is about the best I figure I can do for now.

__________________
Hermit is offline
Delaney Likes This 
Reply With Quote Quick reply to this message
Reply



Quick Reply
Message:
Options
Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
Kegerator temperature fluctuations buzzbromp Beginners Beer Brewing Forum 4 07-01-2012 05:55 PM
temperature fluctuations Tiredboy Beginners Beer Brewing Forum 3 04-17-2012 03:55 PM
Temperature fluctuations PickledFetus Fermentation & Yeast 6 10-19-2011 03:15 PM
How bad is temperature fluctuations? codeblue2k General Beer Discussion 9 02-18-2011 03:39 AM
Temperature fluctuations NWPAbrewer Beginners Beer Brewing Forum 1 07-08-2008 09:31 AM