Strong rubbing alcohol smell

[Coontail]

I deemed my second beer finished today and after tasting the sample it had a strong rubbing alcohol or hot smell to it. Not sure why.

I've read it could be because of too hot of a fermentation or I've also read corn sugar can cause this. I used a smack pack of 1272 and the recipe required a pound of corn sugar. The fermenting chamber never got above 70

 

[Yooper]

I deemed my second beer finished today and after tasting the sample it had a strong rubbing alcohol or hot smell to it. Not sure why.

I've read it could be because of too hot of a fermentation or I've also read corn sugar can cause this. I used a smack pack of 1272 and the recipe required a pound of corn sugar. The fermenting chamber never got above 70

The fermenting chamber might have been 70? Do you have a stick on thermometer or a thermowell or something to ensure that the beer itself never got over about 72? That yeast strain is best at under 72 degrees (I ferment it lower), but sometimes a very active fermentation will be up to 10 degrees warming than the air surrounding it, that's why I ask.

 

[Coontail]

The fermenting chamber might have been 70? Do you have a stick on thermometer or a thermowell or something to ensure that the beer itself never got over about 72? That yeast strain is best at under 72 degrees (I ferment it lower), but sometimes a very active fermentation will be up to 10 degrees warming than the air surrounding it, that's why I ask.

I'm using a chest freezer with an inkbird temp controller and the probe is directly against the side of my plastic carboy so it should be pretty accurate. I'm positive it didn't get above 70 though

 

[brewcat]

What temperature did you ferment at? Make sure to have something blocking the probe so it only reads the fermentation temp. A piece of foam works. Lower the temp next time.

How long was it fermenting? How old is it? Extra aging might help.

How old was the yeast? And the OG? A smack pack was probably less than a desirable pitch rate. Pitch enough healthy yeast.

 

[Coontail]

What temperature did you ferment at? Make sure to have something blocking the probe so it only reads the fermentation temp. A piece of foam works. Lower the temp next time.

How long was it fermenting? How old is it? Extra aging might help.

How old was the yeast? And the OG? A smack pack was probably less than a desirable pitch rate. Pitch enough healthy yeast.

I'll try to answer most of this

It was set to 68 and would climb to 69 and then would be cooled

The pack was only a couple days old

I wrap my fermenters in a towel so it should only be reading the temp of the fermenter

It fermented very quick. Went from 1.055 to 1.013 in 5 days. I pitched right at 68 degrees

I did also read that a not big enough pitch could cause the odor

I'm planning on aging for at least 3 weeks

What temperature did you ferment at? Make sure to have something blocking the probe so it only reads the fermentation temp. A piece of foam works. Lower the temp next time.

How long was it fermenting? How old is it? Extra aging might help.

How old was the yeast? And the OG? A smack pack was probably less than a desirable pitch rate. Pitch enough healthy yeast.

 

[RM-MN]

I'll try to answer most of this

It was set to 68 and would climb to 69 and then would be cooled

The pack was only a couple days old

I wrap my fermenters in a towel so it should only be reading the temp of the fermenter

It fermented very quick. Went from 1.055 to 1.013 in 5 days. I pitched right at 68 degrees

I did also read that a not big enough pitch could cause the odor

I'm planning on aging for at least 3 weeks

This might be the cause. You only want to cover the probe with an insulator. When you wrapped the fermenter with a towel it restricts the ability of the freezer to cool the wort and although your freezer was trying to control the temperature the fast fermentation could have raised the temperature of the wort too high before the freezer could cool it with that insulating layer.

 

[Coontail]

I did think of that, although I haven't had any issues with this before. My brother had his oatmeal stout in there at the same time and it came out fine.

Better luck next time I guess, I'll use a different way to insulate the probe next time and let this puppy sit for a couple weeks

 

[flars]

I did think of that, although I haven't had any issues with this before. My brother had his oatmeal stout in there at the same time and it came out fine.

Better luck next time I guess, I'll use a different way to insulate the probe next time and let this puppy sit for a couple weeks

I was taking some pictures this morning so I snapped this. The bungee cord is long enough not to exert too much pressure on the carboy. The stryrofoam covering the foam pad has a narrow groove to accommodate different types of probes.

 

[Coontail]

I was taking some pictures this morning so I snapped this. The bungee cord is long enough not to exert too much pressure on the carboy. The stryrofoam covering the foam pad has a narrow groove to accommodate different types of probes.

View attachment 565832

Thanks! I'll give this a try, I heat my chest freezer with two light bulbs so I'll have to invest in reptile heating pad

 

[GPP33]

What fermenter are you using? Is there room to drill a ~3/8” hole in the lid? If so run one of these through a 1/4” grommet using your inkbird. You went through the trouble to get a chest freezer to ferment in, why not actually control the temp of the beer instead of the air temp?

https://www.amazon.com/gp/product/B01A6DIPFM/?tag=skimlinks_replacement-20

 

[RM-MN]

I did think of that, although I haven't had any issues with this before. My brother had his oatmeal stout in there at the same time and it came out fine.

Better luck next time I guess, I'll use a different way to insulate the probe next time and let this puppy sit for a couple weeks

When you put 2 brews in the fermentation chamber you can only control either the ambient temperature in there or one fermenter. Every ferment is different and proceeds according to what the yeast wants to do. Your brother's oatmeal stout might have fermented slower and cooler while the yeast in your went crazy and fermented too fast which led to a hotter fermentation and that produced the fusel alcohol.

 

[Coontail]

So after cold aging just a week the flavor has improved drastically. I'll keep an eye on temps better next time so I'm not cutting it so close