I need some help with this one. I haven’t experienced this in the past and generally I have been problem free with my finished beers for the most part. But the past 3 batches have had a varying level of a rubbing alcohol flavor/aroma. I brewed 3 batches back in Sept which 1 of them came out fine while the next two in a row had this rubbing alcohol flavor and aroma. I at first pinned it to the yeast I used. It was Omega Amercian Ale and it was the first time I used it. But now a few months later, I brew a Robust Porter using US-05 and upon tasting the hydro sample at kegging Im hit with the same off flavor/aroma. Now, it is only slight but enough to remind me of what I tasted previously. I do not like this trend.
My question is what kind of infection (if that could be the problem) would cause a rubbing alcohol character? We can rule out high fermentation temps, I use a chest freezer with a Johnson Controller. These batches fermented 66-68*. And for that, I can see 1 batch maybe but not 3 in a row. The 2 prior batches with this partial mash batches, this last one was all grain…so it’s not limited to a certain process. Not much has changed, no new equipment, process, hoses…etc. I use filtered tap water and campden tab…shouldn’t be a problem there. This is something new, never had this before in 6 yrs of brewing.
The common demoninator with all 3 batches is my boil kettle, I transfer to the fermenter at the end of the boil via tubing and oxygenate with pure o2. I thought maybe I have been over oxygenating, but again never a problem before this. It would take excessive use of pure o2 to increase fusels. And to me this isnt’ so much fusel, it’s more rubbing alcohol. I use PBW and Starsan. It’s not a fermenter problem, each batch used a different fermenter. All other factors seem ok, good mash, good boil, hitting my numbers. The ph’s are good, FG’s…etc. Just a slight rubbing alcohol flavor and aroma. What can be causing this?
To me, rubbing alcohol either means fusels or just green beer that’s a little hot on the ethanol and hasn’t mellowed out yet. What was the OG/ABV on these batches? Are you absolutely 100% sure that fermentation temperature couldn’t have spiked a bit early in fermentation?
Rubbing alcohol (isopropyl alcohol) and nail polish remover (acetone) do have some similarities, so maybe it’s light enough that you’re conflating the two aromas? Acetone could be a yeast byproduct at certain temperatures as well. Maybe it’s just produced at a certain temperature range with that yeast. Try dropping temp a few degrees lower next time maybe?
If you are really confident about your temp control it could also be a wild yeast infection within your brewery in general. some wild yeasts can throw terrible acetone which as Toby points out could easily be mistaken for rubbing alcohol.
What do you use for sanitizing?
As Mark (S. Cerv.) has pointed out on many occasions StarSan is not a good protection against yeasts/fungi.
If you’ve been using star san exclusively for any time perhaps try to shock the system with either a bleach/vinegar solution (lookup how to make this because it’s potentially dangerous) or maybe just switch to idophor for a while. (or, alternately, if you have been using idophor try star san!)
I always taped my temp probe to the fermenters and did so on the last 2 batches a that always worked well for me. This last batch I have upgraded to a glass carboy and bought a stopper thermowell so I am now reading temps fright from the center of the fermenting beer. The last batch temps I pitched closer to 68-70* and then temps dropped to about 64 as fermentation started and ramped up to 66-68. As fermentation died down I bumped temps to 68-70 to finish off as 8 have always done. The gravities on theses beers were around 1.050+ on the first two and this last one about 1.068. FG were all around my target.
I can see temps getting up there on a batch here or there but 3 in a row with different yeasts and temps seems to point me to something else. I could be confusing the off flavors I am not the best at describing them. The best I cant compare it to is rubbing alcohol but. Its not as “perfume” like as nail polish remover. The whole band aid/medicinal thing I dont onow I have ever tasted…but I dont think Chlorophenols is a problem.
I had the same thought…maybe change out my soft tubing and give my ball valve on the kettle a good cleaning. I appreciate the replies and the help.
Thats good info thanks. I have always used Starsan. Im kind of leaning towards your thoughts of a bug in my system. The beers have just been off. This last batch seems to be the least effected but I have the same gut feeling about it as well.
I have a question. What about my .5 micron Stainless Steel oxygen stone. I have only been soaking it in Starsan. I am now reading that is not good enough?
have you ever used chloroseptic for a sore throat? that is chlorphenols straight up. pretty intense but if you can imagine a subtle version of that you get a pretty good idea of what people are talking about with medicinal off flavors. The Band-Aid thing has always been more like burning/old electrical wiring insulation to me.
It may or may not be. I’d be concerned that a Star San soak wouldn’t be able to hit all the nooks and crannies in the stone. I’d boil the sucker if there’s any remote chance that you may have an infection issue.
I’m not referring to scented nail polish remover (where they’re trying to mask the acetone). Ever smelled paint thinner (acetone based paint thinner is, or at least used to be, pretty common)?
Gotchya that makes more sense. I wouldnt say its that intense but that is a tough one to distinguish. If it could be acetone from yeast…what causes that?
The strain of yeast is a factor (some strains and wild yeasts produce more). Fermentation conditions play a part as well (the ones that do will produce more under stress).
Best I could do is boil it or bake the air stone. Ill also switch up sanitizers as mentioned and replace my tubing. All pretty easy precautions.
2nd question…is any wild bug/bacteria only a concern of everything post boil? As in can I be transfering anything over that the boil wont kill off? My mashtun is new but my kettle has many batches under it. I have a ball valve on it that might be holding something possibly. Also I use a wooden dowel in the boil as a dipstick…is that a bad practice maybe introducing something into the boil?
This place has really helped me hone in a lot of improvements in my brewing. Thanks all.
On a related note… My oxygen stone is permanently affixed to the end of a stainless steel tube close to 3 feet long. I’m thinking the only way to sanitize it is to bake it in the oven. Anyone know what temperature and for how long?
you pretty much only have to worry post boil. are you chilling in the kettle with an immersion chiller? or do you use a plate or counterflow? I would expect the ball valve gets hot enough to be at least reasonably sanitary but I do like to give it a shot of sanitizer before runoff just to be safe.