Odd Fermentation

[twitchster]

I haven't seen this issue posted on the forums so I'm not really sure if anyone has had this happen to them before. I brewed a big beer about 9 days ago and pitched a 1.5L starter (before decanting) that was on a stir plate for about 24 hours. In this starter was 2 vials of White Labs WLP001 yeast. The OG at the time of pitching the yeast was 1.072. The very next day after pitching the yeast, I get a SUPER aggressive fermentation. I fitted my conical with a blow off tube because I figured this would be the case. Fermentation continued to be aggressive for the next couple days and then really started to slow down to about 1 bubble every 35-40 seconds. I noticed the conical was fairly cold to the touch so I was afraid that the wort may have become too cold for the yeast to do their job properly. I put my hands on the conical, and just the warmth from my hands had the fermentation back up to bubbling at about a bubble every 10 seconds. I moved the conical into another room and put a space heater in there with it. It quickly went from averaging 35-40 seconds between bubbles to 3 seconds between bubbles, but only while the spacer heater is on. As soon as the heater kicks off, it immediately starts fermenting slowly again. Every time the heater is on though, the fermentation almost IMMEDIATELY picks back up to a bubble about every 3 seconds, and just as quickly as it sped up, when it turns off, it slows down. I should also mention that this is an extract recipe and only my second batch ever. Oh, also, ambient temp of the house is roughly 72. So, all that being said, should I leave the space heater in there or take it out and let the yeast slowly do it's thing? Thanks for the replies in advance guys!

 

[flars]

You really do need a thermometer strip on the outside of your fermentor to track the wort temperature. With normal body temperature anything under 98° will feel cool.
An ambient temperature of 72°, high OG, and two packs of yeast with a starter, your wort could have been fermenting at 80°. Optimum temp range for WLP001 is 68° to 73°.
I haven't used this yeast so I don't know what kind of off flavors it will create at high fermentation temps. High fermentation temps can produce fusel alcohols. (This I am familiar with.)
Let this one sit at room temperature. In another week take a SG reading to see where the fermentation is at. Check the SG again after another three days.
The CO2 you see being released with the heater on may just be off gassing of the CO2 in solution. Fermentation might be complete. The beer will now need time on the yeast cake to clean up off flavors.

 

[Omahawk]

I have not had this happen, but I'd be interested in understanding more about where you are with fermentation before guessing at what's going on.

• You mention that the conical feels cold, but do you know what the temperature of the fermenter is/was? 72 degrees ambient temp room means that the fermentation temp was at least that high - likely warmer - which is PLENTY warm for 001. Even with a big beer, 2 days of aggressive fermentation could have finished off the bulk of the attenuation phase.
• Have you checked the gravity? I would guess you're done with the attenuation phase of fermentation, but check your gravity and see if you're there. If so, warming up the yeast will help with conditioning phase of fermentation. But changing the temperature too much can stress the yeast.

Warming the beer up could probably force some off-gassing leading to more airlock bubbling, even if it's not actually a sign of more attenuation.

 

[Omahawk]

An ambient temperature of 72°, high OG, and two packs of yeast with a starter, your wort could have been fermenting at 80°. Optimum temp range for WLP001 is 68° to 73°.... High fermentation temps can produce fusel alcohols. (This I am familiar with.)

This, too.

 

[jakenbacon]

Okay, so you own a conical, and are making starters with your stir plate, but don't have a thermometer and are referring to bubbles??? Priorities sir, priorities...... Sorry not trying to be rude but a thermometer is like super cheap and an absolute necessity.....The bubbles are from the pressure of your hand pressing on the conical, or if long enough CO2 is coming out of solution....

 

[twitchster]

Okay, so you own a conical, and are making starters with your stir plate, but don't have a thermometer and are referring to bubbles??? Priorities sir, priorities...... Sorry not trying to be rude but a thermometer is like super cheap and an absolute necessity.....The bubbles are from the pressure of your hand pressing on the conical, or if long enough CO2 is coming out of solution....

Ok, I should have mentioned the fact that I do have a thermowell in the conical with a dial thermometer in it. I just don't know how well the thing is calibrated because the ambient temp of the room the conical was in is 72 degrees. The thermometer was reading 66 degrees but if the wort is supposed to be at LEAST room temp how can the temp of the wort be cooler then ambient temp? As far as owning a stirplate and conical, I was waiting to homebrew until I saved up enough to buy the things that I wanted and knew I would eventually buy anyway then spend money on something that I knew I would eventually replace. Am I wrong for having this mentality? By no means did I ever claim that I was an advanced brewer, which is why I joined these forums to begin with. To learn. There are a lot of very knowledgeable people on here that I know I can learn from. I'm still very new to all of this and therefore, still very paranoid I will mess up a batch.

I haven't taken a gravity sample just yet, I was actually going to dump the trub today and take a gravity reading. I'll do that and then check again on Saturday. If the gravity is the same I was going to dry hop on Sunday. So, if I understand this correctly, I should let it sit at ambient temp for the remainder of fermentation. Did I understand that correctly? Again, thanks for the help guys. Sorry for the stupid questions, I just want to make sure that I don't do something wrong.

One last stupid question. What is fusel alcohol?

 

[kombat]

Fusel alcohols are harsh, unpleasant-tasting alcohols that are produced by yeast when they are stressed (from underpitching, underoxygenation, or most commonly, fermenting too warm). Fermentation temperatures are crucial during the first 3-5 days of fermentation, then they become much less important. Fusel alcohols taste "hot," or like varnish or nail polish remover smells.

As mentioned, the bubbles you're seeing (especially on the timelines you mentioned, i.e. within seconds or minutes) are almost certainly not due to an immediate acceleration in fermentation triggered by the heat from your hand on the fermenter, or even the space heater kicking on momentarily. Rather, they are mostly likely due to you pressing on the fermenter, causing it to flex, or the space heater warming the room, which would cause the pressure to drop, which would disrupt the equilibrium of the gas in solution in the beer, causing CO2 to off-gas and produce bubbles.

 

[twitchster]

Fusel alcohols are harsh, unpleasant-tasting alcohols that are produced by yeast when they are stressed (from underpitching, underoxygenation, or most commonly, fermenting too warm). Fermentation temperatures are crucial during the first 3-5 days of fermentation, then they become much less important. Fusel alcohols taste "hot," or like varnish or nail polish remover smells.

As mentioned, the bubbles you're seeing (especially on the timelines you mentioned, i.e. within seconds or minutes) are almost certainly not due to an immediate acceleration in fermentation triggered by the heat from your hand on the fermenter, or even the space heater kicking on momentarily. Rather, they are mostly likely due to you pressing on the fermenter, causing it to flex, or the space heater warming the room, which would cause the pressure to drop, which would disrupt the equilibrium of the gas in solution in the beer, causing CO2 to off-gas and produce bubbles.

Thanks man, this actually helped a lot. I can't wait to get home and try my sample now.