Ferm chamber - Aldehyde issues?

Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum

Help Support Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
Joined
Oct 20, 2005
Messages
7,732
Reaction score
76
Location
Nanaimo, BC
I know two guys that are having issues with their beer having aldehyde. 4 batches, 3 diff dry yeast strains. I was theorizing that it could be temp issues. They just started using a freezer with a temp controller. I thiink the temp is set at 17c.

They don't have fans in the freezer. Could the bottom of the kegs be getting to cold? They sit right on the bottom of the freezer. No spacer or anything. I believe their temp probe hangs in the middle.

Freezer is a small one. Holds 2 glass carboys.

Their first batch was to young and the second used the same yeast (S-05) so I thought it might have been either to short a fermentation time or yeast quality issues, but they aged the other beers a decent period and used windsor and s-04 for the last two beers.

The aging helped but their is still some aldehyde in those last to beers. The FG's seems within range and did not change after a week. I will note that it did take some time to finally arrive at the FG. Dropping from say 1.030 to 1.012 took much longer than I expected.
 
First time I used my Fermentation Chamber with a thermowell. The thermowell is mounted on the carboy bung, and the thermometer slid down inside the thermowell. This does measure the fermentation temp accurately, however since it's in the middle of the carboy, it caused the freezer temp to overshoot (Ambient was around 42).

I had the same flavor in my first beer. I attributed it to the carboy getting too cold, yeast dropping out of suspension and not being able to clean up after themselves. FG was fine as well.
 
I vote taping thermometer probe to the side of the carboy/keg as opposed to ambient. That way there is more mass to keep the thing turning on off too much:mug:. When I get my sanke fermenter going the thin metal should be good enough to approximate the temp I think.
 
I vote taping thermometer probe to the side of the carboy/keg as opposed to ambient. That way there is more mass to keep the thing turning on off too much:mug:. When I get my sanke fermenter going the thin metal should be good enough to approximate the temp I think.

Agree.

I've got mine now taped to the side with bubble wrap and bungee cords to keep out the ambient temp reading. It's the best method I've found after lots of trial and error and research. Also, the more thermal mass in the fermentor the less temp swings.
 
Is the probe onbthese units waterproof?

If so what about placing it in a container of water to get a bteer ambient temp?

They are using 2 carboys at a time with diff beer and yeast strains so taping to a glass carboy might not be the best.
 
Probably would be ok if the wire insulation isn't immersed. Then you are controlling the ambient temp, not the beer, just so it is clear so I would shoot for lower ambient like in the mid 50s during the start of fermentation and then slowly raise it up.

You can probably get a water bottle and punch a hole in the top of the cap and insert the probe until it is slightly under water. Taped in place.

Also, like you said probably put a piece of wood or something to keep the bottom from touching especially in a chest freezer.
 
How did this turn out? The only beers that i have brewed that showed any acetaldehyde were done in a chest freezer. I've brewed over 100 other batches without ever dealing with it. My gut was that it had to somehow have something to do with the freezer but i didnt think of what it could be. I do the temp probe on the outside but insulate it very well.
 
I have had the same problem with my chest freezer. The probe taped to the side and temp at 62f. I think it might be a contamination in the freezer that is causing it.
 
I have had the same problem with my chest freezer. The probe taped to the side and temp at 62f. I think it might be a contamination in the freezer that is causing it.

Aldeyhdes are a fermentation byproduct. Unless you have perpetual fermentation occurring in your chest freezer, I highly doubt you're experiencing an external aldehyde infection.

I'd look at your 62 degree fermentation temperature. What yeast strains are you fermenting that cold? What's your typical fermentation timeline? Are you raising the temperature at the end?
 
I'll post a little more specific information and throw it out there for some theories. I've been brewing for over 7 years and easily have over 100 batches under my belt. I of course have made my mistakes and learned some things the hard way but I pretty much have my processes dialed in now.

The only times I have ever detected acetaldehyde in my beers is with the recent beers I have fermented in my my temperature controlled (stc1000) upright freezer. There is a heater fan inside the freezer that will cut off when the ambient air temperature is above 80*. I have the tolerance set as +/-0.2* C.

All 5 of the beers I have fermented in this freezer have shown fermentation flaws. 4 Acetaldehyde, 1 bannana. I have brewed several batches between these 5 flawed beers using the same eqipment and processes. The only difference is those beers where fermented in an ice water bath in a closet and they came out flawless.

So, background info on my process so we can get past the typical, pitch rate, ferment temp, pitch temp and sanitation advice that normally applies when dealing with acetaldehyde. I brew 10 gallon all grain batches. Post boil sanitation is as follows. I cool with a counterflow chiller that is stored with a PBW solution when not in use. I use silicone tubing and a march pump. I hook up the tubing and CFC to a bucket of starsan then flush the system of PBW with starsan then recirculate the starsan for several minutes. I then hook up the starsan filled setup to my kettle toward the end of the boil. At knockout i flush the starsan out of the system with hot wort then recirculate the 200*+ wort through the tubing/cfc/pump setup for 5-30 minutes. I start the water counterflow and chill the entire kettle to 150* before clamping the end of the hose off then pumping into a clean sanatized fermenter. The wort in the kettle stays above pasteurization temperature and flows out the other end of the sterilized chilling setup at 68* into a clean sanitized fermenter. I can't think of a more sanitary way to transfer the cooled wort. I oxygenate with pure O2 and a .5 micron air stone for 60-90 seconds depending on the OG of the wort.

Now the specifics on the funky beers:

Batch 1: 1.054 OG Porter. O2 for 60 seconds. Mr Malty calculated starter of wlp001 pitched into a 12 gallon stainless conical in the ferm freezer at a wort temp of 62*. Fermented at 62* for 5 days ramped up to 70* over two days then held at 70* for 2 weeks before racking to kegs. Acetaldehyde. Lots of it. Never cleared (the acetaldehyde) even when the porter was several months old.

Batch 2: 1.074 Scotch Ale. 90 seconds of O2. Fermented in 12 gallon conical with repitch slurry from previous batch (MrMalty calculated). Fermented under the same conditions. Chalked the acetaldehyde in this one up to a bad batch of yeast.

Batch 3: 1.050 APA oxygenated for 60 seconds. Pitched MrMalty caluclated starters of wlp007 into two better bottles at 62*. Fermented at 62* for 5 days ramped up to 70* over two days then held at 70* for 2 weeks before racking to kegs. Acetaldehyde. Lots of it. Never cleared (the acetaldehyde) even when the porter was several months old.

Batch 4: IPA 1.070 pitched into a 13 gallon food safe container converted into a fermentor with three hydrated packets of Nottingham. Same temps as before. This one came out with bananna.

Batch 5: 1.076 Double IPA. 120 seconds O2. 3.5 packets of hydrated US-05. Pitched at and fermented for 5 days at 64*. Ramp to 70* and held for 2 weeks. Acetaldehyde again.

You deserve a high 5 if you made it through that word fort. I'm open to any and all theories and suggestions.
 
Here's a couple of things from my experience. I use a fermentation chamber too. I have done two 2.5 gal batches in there that both had off flavors. I read in Mitch Steele's book that when they went to pure 02 they were doing it for too long and getting these flavors. I usually put a 5 gal batch on for 60 seconds. I did the same with the small batches and I got the off flavor.

Since these batches were small I also have a theory that the cooling part of the chamber didn't click on soon enough.
I'm pretty sure that between on of those things I have my issue.

If I were you, I'd just try the 02 for 30 seconds on an average beer and see what you get, if you think you are measuring wort temp properly.
 
Thanks for the input. These are 10 gallon batches which kind of cuts the times in half but I may dial it back next time just as an experiment.

The theory I'm currently running on is that I'm insulating the probe I tape to the side of the fermentor too much and that the freezer gets too cold affecting the yeast that is closest to the uninsulated portion of the sides. I haven't tested it yet. The prospect of another 10 gallons of green apple beer is discouraging.
 
Is it possible that the floor of the freezer gets really cold when the freezer is running? Maybe I'm over-chilling the flocked yeast, keeping it from doing it's cleanup work...
 
i wouldn't write off the possibility of overpitching causing acetaldehyde.
 
Is it possible that the floor of the freezer gets really cold when the freezer is running? Maybe I'm over-chilling the flocked yeast, keeping it from doing it's cleanup work...

If you don't have a fan moving the air around all the time the bottom of your freezer will get much colder than the top. I've seen as much as 8* difference from the top to bottom in my chest freezer.
 
I don't understand why you are ramping the temperature up. I always go down (mostly to clear the beer), except occasionally with a larger I'll do a diacitital rest. I'd try pitching a bit less and letting it set a bit longer.
 
I don't understand why you are ramping the temperature up. I always go down (mostly to clear the beer), except occasionally with a larger I'll do a diacitital rest. I'd try pitching a bit less and letting it set a bit longer.


Most off flavors occur during the first phases of fermentation. Keeping a lower temp in this stage (although 62 is too cold IMO) will help prevent off flavors.

A lot of guys will ramp up temperature after a week or two to build up the yeast activity to ensure a full fermentation.


Sent from my iPhone using Home Brew
 
In my upright freezer, having good air circulation is critical. When I have active fermentation, I have a desk fan on the bottom shelf and a panel of computer fans hanging from the top, both running constantly. When fermentation is complete or I'm in between batches and using it as a beer fridge, I only run the computer fans.

When the desk fan and computer fans are running, the temperature is constant across the freezer.

When only the computer fans are running, I have about a 5F difference between the bottom shelf and the first shelf.
 
Thats interesting. I'll definitely have to get a fan in there. I imagine the convection will help with the temperature exchange as well. I'm curious where you mount the temp probe for your controller.
 
I tape it to the side of the bucket/carboy, about half way up. I cover it with a couple folded paper towels to insulate it from the air.

When I ferment two five gallon beers side by side (same shelf), their temps will be within 1F of each other.

When I'm using it as a beer fridge, I put the probe in a bottle of water on the bottom shelf. That way I don't accidently freeze my beer... again.
 
This has been a great thread. I've been measuring temps in my chest freezer and the difference between the top and the bottom is significant. I also was thinking through my lagers, and my best lagers have been made in my SOFC, which has massive airflow.

Time to fan up the chest freezer.
 
I rigged 2 120mm computer fans wired to a 12 volt wall wart in mine. I also have my fermenter sitting on a 2 inch thick piece of foam so it is not resting directly on the freezer floor. I also use the stc-1000 with the probe touching the side of the fermenter, then a piece of a thick koozie taped over it. on the heat side I just have a 15 watt light bulb to help take the swing out. so far so good.
 
Well, I ordered a beer bug with the internal temp probe so I can keep track of exactly what's going on inside the fermentor (real time gravity and temperature). I'm going to get the fermentor up off the floor of the freezer, add a fan and insulate the temp probe like I have been to see how it goes. I might throw another thermometer in the freezer too. That would give me ambient, beer and controller probe temperatures.

Brewing a Rye IPA on Friday. Wish me luck.
 
Just got my first chest freezer (14.8CF) and wired in a spare PC fan after a couple days. I checked after 24hr and it was fermenting great (04 yeast and 45 sec of O2), the smell that was present in the chamber was something I have never noticed since I always fermented in my basement in the open air. Was that Aldehyde that I was smelling? It was too much for me to take when I stuck my head in there to verify the stick on thermometer temps on my BMB's to the temp controller.

After reading this I think I need a small desk fan placed on the "hump" of the freezer to circulate better and it sounds like it wouldn't hurt to cut up a pallet and line the bottom to get them off the floor of the unit. Have 10 gallons of a blonde in there now for my first club comp entry next month, hope it turns out well but also this should be a good learning experience from people with more expertise than myself.
 
Fermented out great to 1.01. Now it's (blonde) in the secondaries, one on strawberries and one on mangos
 

Latest posts

Back
Top