Heated Conical causing off-flavour?

[beerbeer95648]

I am have been trying to track down the cause of off-flavours in the last 4 batches I have brewed. Every batch has tasted very good until day 7-8. At that point it picks up this organic acid sour/harshness, and loses its character. In addition 3 of those 4 times sulfur has showed up at day 7-8. This is all using WlP001. I have been brewing for a long time, and the main change has been using a heated and cooled conical. With the colder nights lately I am wondering if the heater, which is covering much of the cone, is stressing the flocced yeast and causing it to release these compounds? And, I am wondering if the lack of movement in the beer due to the bulk of the fermentation being done is exacerbating the heating stress? I oxygenate for 2 minutes for a 12 gallon batch, and pitch healthy properly sized starters. I always get very good action by morning and very good attenuation. Last straw was the cream ale that is in there now. Day 6 it was down to 1.006 from 1.050 and tasted a dream. It was clean, dry and flavorfull. Day 8, it is bitter/harsh, sulfury, and bland.

 

[Brew-boy]

I have been using a S.S. conical for years and never had this problem. Is yours a plastic or Stainless conical? If stainless do you disassemble your valves and boil them?
I also use a fermwrap around my conical to heat it in the cold months.

 

[beerbeer95648]

Stainless Morebeer heated and cooled conical. Old threaded valves, not there newer design. I do disassemble all valves and boil them, then assemble them wet in a bucket of starsan. I boil out my tubing and heat exchanger in a loop for 20 minutes and transfer to a closed system. I take sanitation very seriously. This issue seems to be a yeast stress issue. Where is your heating element in relation to the cone?

 

[beerbeer95648]

Well, I think I am going to have to move this thing in the house next time and leave off the heating element.

 

[StMarcos]

You might consider an experiment that lets you know how much the temp is varying from top to bottom. I used to use a stick-on heater on my stainless conical and found that the beer at the top was MORE than 10degF warmer than that at the bottom. Without active fermentation to stir things up, stratification can be significant. I managed to mostly solve the problem by using a heated/cooled ferm chamber. Top to bottom differences are closer to 1 or 2degF now. Although the heated beer at the walls will still tend to rise, air blowing around the chamber counteracts the effect quite a bit.

I don't know if temp issues could cause the off tastes you describe, but it might be something to consider....

 

[beerbeer95648]

10 degrees! That was what I feared. I had been thinking last night that I may build an insulated chamber and only use the cooling function on the morebeer fermenter in the Fall and Winter. I have never really seen a true case of autolysis in a homebrew setting (saw it in a production brewery in my past life), but this is what the flavor change reminds me of. And the fact that the stress is happening at the very end of the fermentation when the natural heat is fading seems to point to an excessive stress factor such as the stratification you saw.

 

[daksin]

Just out of curiosity- are you fermenting under pressure?

 

[JeepDiver]

If it was me (Wish I had a heated/cooled conical) I would cut the heat off after the first few days of active fermentation were over. My brew closet gets low temps in the winter so I will use a heating pad to begin with, but once fermentation has really got going, I cut it off and it seems to do fine on it's own.

 

[beerbeer95648]

If it was me (Wish I had a heated/cooled conical) I would cut the heat off after the first few days of active fermentation were over. My brew closet gets low temps in the winter so I will use a heating pad to begin with, but once fermentation has really got going, I cut it off and it seems to do fine on it's own.

I think you have the right ideal. That is the route I think I need to go. I think this issue is showing up partially because I tend to start at around 65 degrees for the first 2 days, then ramp up to 70 toward the end. I then usually leave it set for 70 for the next 3-4 days. So, for 3-4 days it is sitting overnight where it is 30 degrees in the garage with the heating element cycling to maintain 70 degrees. And, I am sure it takes a while to reach the probe in the center with such little movement in the fermenter (besides what the heater is causing), and the whole time I am probably cooking the stuff near the wall.

Daksin, I purchased this fermenter years ago while living in apartments where I couldn't fit a temp controlled fridge, but had not been using it till recently. I just recently upgraded the pressure capable lid. I will normally bung the fermenter after the D-rest, then put a couple psi on it to facilitate harvesting and sample taking. I haven't been able to use any of the harvested yeast however due to the stressed behavior it shows at the end. But no, I mostly ferment using a blow-off assembly.

 

[beerbeer95648]

Just a follow up for anyone who cares, but more careful use of the heating element solved this issue. I have been brewing without the heating element and have had no issues. Thinking back on it, I dont know why It took me so long to figure out this was a problem. The element running during the winter was doing a number on the recently flocculated yeast. I think in the future I could run it earlier in the fermentation like JeepDiver stated, then cut it as things slowed down. Probably in conjunction with an earlier yeast drop.