Brewmistake on stuck fermentation, when will I know if brew is oxidized?

[fasttimes]

Brewed up a stout after a 2 year break from brewing. I knew the potential was there for mistakes, but I was really careful and brew day went well. Except it never got a really good vigorous fermentation (using just one dry yeast packet) even though gravity after boil was spot on. So after 6 days I checked the gravity and the beer was no where near where I expected it to be, krausen was non-existant. Here's where the snafu came in, I ordered another yeast packet and had a brain fart and blasted the beer with pure O2 for a good 3-4 min before pouring it in. Wasn't thinking and then only later did I realize what a mistake I had made.

Question I have, how long till I know if I ruined this batch of beer? When will I taste the oxidized flavors in the beer?

Was thinking of making a starter to try to get the stuck fermentation going but don't want to waste the time if I have already ruined the beer.

 

[TechFanMD]

At least it isn’t an IPA. I would let it ride and it may be fine. You could always add a bit of DME dissolved in boiling water then cooled to ensure the yeast are active and scrub some more oxygen but of course this will also add oxygen so maybe not the best idea.

My bet is that as long as you drink it fairly quickly you’ll be fine.

Lessons learned - you probably didn’t even need to add more yeast and should just have waited. Without a gravity reading, you can’t be sure how fermentation was really going. How did you determine if it had a vigorous fermentation? Airlock activity is not a great gauge of how fermentation is going - too many variables (leaks, bubble sizes, etc)

 

[fasttimes]

There was very little air-lock activity at all, but I was judging it by the fact that the krausen had completely dissapeared and the beer looked flat as can be. I just now took another gravity reading, started at 1.054 and now 12 days in and I'm only at 1.033. Swirling, raising the temps, and the O2 burst with second yeast packet has only gained 1.034 to 1.033.

 

[Gnomebrewer]

How are you measuring SG, you're not using a refractometer are you?
Airlock is a notoriously unreliable way of gauging activity.

 

[fasttimes]

Yes, refractometer.

 

[Gnomebrewer]

Yes, refractometer.

Refractometers don't work for gravity readings once alcohol is present. The alcohol skews the reading. You need to use a calculator to adjust your measurement to get a true gravity reading.
Using https://www.brewersfriend.com/refractometer-calculator/ your real final gravity is 1.021. Still high, but not as badly so.

 

[fasttimes]

Gotcha, ok makes sense.