[jwaldner]

I'm not sure if this an actual fermentation problem or not and can't quite put my finger on it but I thought I would post it here to see if anyone else has experienced something similar.

I recently bought two chest freezers, one to use to control my fermentation temps and put a carboy in and the other to use as my keggerator/fermenter. I have never fermented in an enclosed space but two beers I recently made just did not turn out as expected and I have made these with the same process before with the exception of fermenting in the chest freezers.

One was an APA that the yeast just did not seem to get going on and lagged quite a bit and then developed some infection after several attempts to get it going. It had to be dumped. The other is a smoked porter I'm currently fermenting but the yeast also seems to be acting very sluggish and the porter is developing a slightly sour taste.

Again, my process hasn't changed at all with the exception of using the chest freezers for fermentation control. I'm really reaching here but is it possible that the enclosed fermentation and trapped CO2 could affect the performance/health of my yeast causing these issues?

Thanks and Cheers!

[Hokerer]

Your beer's almost certainly not suffocating.  How are you measuring your temperature.  Maybe it's just the fact that you're now controlling your temps (meaning you're now correctly fermenting cooler) that's making the yeast seem sluggish to you.  The cooler the temps, the more "sluggish" your fermentation could appear.  Also, depending on how you're measuring/regulating the temps in the freezer, maybe things are way cooler than you think.

[jwaldner]

Your beer's almost certainly not suffocating.  How are you measuring your temperature.  Maybe it's just the fact that you're now controlling your temps (meaning you're now correctly fermenting cooler) that's making the yeast seem sluggish to you.  The cooler the temps, the more "sluggish" your fermentation could appear.  Also, depending on how you're measuring/regulating the temps in the freezer, maybe things are way cooler than you think.

Thanks for the reply. I'm using a two stage temperature controller to manage/monitor the temp. I tape the temperature probe to the outside of the carboy and then wrap a fermwrap around the carboy and plug in both the fermwrap and chest freezer in. I've fermented both beers at 68F with a 2F differential.

Before I used the chest freezer, I controlled my temps with a round refrigerated "wine cooler." The only difference was the neck of the carboy stuck above the rim and I fasioned a piece of plexi-glass for a top with a hole cut out for the neck of the carboy to stick out. It works quite well and I still use it but wanted more fermentation space and couldn't find a cheap wine cooler anywhere.

I'm pretty confident the temps are correct, but the chest freezer is the only item I've changed in my process with the exception of some new better bottles which I have used before so I thought it would be a point of focus until I could rule it out.

Thanks

[tschmidlin]

I'm pretty confident the temps are correct, but the chest freezer is the only item I've changed in my process with the exception of some new better bottles which I have used before so I thought it would be a point of focus until I could rule it out.

As long as your aeration procedures are the same, rule out "suffocating" the yeast.  Fermentation is an anaerobic process, so unless you're fermenting under pressure CO2 escaping is not likely to be the problem.  Make that really unlikely. 

The first batch could have been caused by bad/weak yeast, and then your fixes caused the contamination.  The second batch may or may not be problematic, give it time to finish then keg/bottle it.  If things are starting to go sour, look for possible sources of contamination.  I know you said your procedures haven't changed, but maybe a hose is finally damaged enough to harbor bacteria . . .

[euge]

Is any part of your fermenter touching the wall? And, how often does your freezer kick on? The placement and treatment of the temp probe is in the best spot? The temp of the air inside the space will fluctuate more readily than the mass of the liquid inside the fermenter.

I'm still suspecting the brew being kept consistently and steadily cooler than what you're used to.

[jwaldner]

Is any part of your fermenter touching the wall? And, how often does your freezer kick on? The placement and treatment of the temp probe is in the best spot? The temp of the air inside the space will fluctuate more readily than the mass of the liquid inside the fermenter.

I'm still suspecting the brew being kept consistently and steadily cooler than what you're used to.

Thanks for the replies. The carboy doesn't touch the wall and the freezer rarely kicks on if at all since my basement stays a pretty constant temp about 66-68F. When I pulled a sample a few days ago the temp of the beer measured what the controller was reading so I think it's keeping pretty steady.

Thanks again

[dhacker]

I'll throw this out . . .

Are you using air locks or blow off tubes? If there is any wort spillage in the freezer from an airlock that bubbled over, or a blow off tube that is, well, blowing off, then the enclosed environment could be a place for the acetobacter bacterium. Does your freezer smell of vinegar when you open it?  If the air locks don't provide a good barrier, the sourness you mention may be the result.

[wingnut]

Bottom line, if everything else in your brew day has stayed the same, and you are pitching the same strain of yeast in the same quantity that you always have... the change in yeast behavior is due to the Freezer. 

I suspect between the more robust design of the freezer... possibly fans blowing where your wine refirgerator may have only had a plate, larger compressor allowing the coolant to get down to 10F instead of 30F... Carboy resting on the floor of the freezer and there being cooling coils in the floor of the freezer... are causing larger temperature swings along the outer layer of your carboy when the freezer is cycleing than it experianced in the wine fridge..   

I know my wine fridge can only get down to 40F because the plate in the fridge where the refrigerent flows only gets down to 30F.  (In the HVAC world the general expectation is that you can only get the air to within 10-12F of the temperature of the cooling coil)  I also know this becuase I wired it to run non stop for 4 hours and the lowest temp it got was 38F.  I suspect your wine setup to be about the same.

Regardless, yeast do not like to see things get cold quickly.  If you drop their temp more than a couple degrees in an hour, they are shocked into hibernation mode, and go to sleep and thow on a few extra protective  layers of protein to keep warm. 

What I would try next is to elevate the carboy off of the floor of the freezer using blocks of wood.  Also, if the freezer "blows" cold air, you may try and divert the blowing air so that it does not blow directly on the carboy.  The next step, if the issue if the freezer coils get colder then the ones in the wine cooler... make a metal box around the carboy...or a plactic bucket around the carboy would work too.. (I like the metal better because it conducts heat better)  keeping the carboy from touching the sides or bottom of this box.  This will create a chamber that act more like your wine cooler did with the cool covnecting from the walls of this box, at probably 10F or so warmer than the rest of the fridge. 


Hope this helps!!