Added Yeast Nutrient at End of Attenuation

I recently got a Refractometer, and I'm loving it. That is, until today.

For those of you that do have one, you probably know that you need to adjust for alcohol content if you want to use it to take readings during or post-fermentation. There are good calculators online and many posts about it. At first, I didn't trust these calculators and would take readings with my hygrometer and compare to the alcohol-compensated refractometer reading. They always compared well, never being more than 0.002 off.

I brewed a Westveleteren 12 clone with O.G. of 1.092. I added 1/2tsp of Fermax Yeast Nutrient near the end of the boil. I pitched a Mr.Malty recommended amount of washed yeast from a batch of a Belgian Amber (OG 1.064, FG 1.007) at 65F. I used a Ceramic Heating Lamp and the Johnson Controls unit from my Kegerator to ensure a fermentation profile that rose to 79F over three days and then cooled down to 67F where I've been holding it since.

Everything was going according to plan. Then today, day 8, I checked the specific gravity and my refractometer read 1.042.

I was hoping to see something along the lines of 1.012. I hadn't seen any significant action since day 4 so I immediately concluded I had my first stuck fermentation. It seemed to be at 2/3 sugar break, so following a staggered yeast nutrient addition from my experience brewing mead, I decided to boil up 4oz of water and add 2 tsp of Fermax yeast nutrient. I cooled it down, added it to the carboy and stirred it in well with my MixStir, making sure to rouse all those sleepy yeasties at the bottom of the primary fermenter.

Then, a few hours later I realized I never compensated for the alcohol. The calculator revealed the specific gravity is actually 1.011, right on target.

I'm trying to relax, not worry and have a homebrew, but it's 10:17am and I'm on antibiotics. I'll have to settle for the first two.

Anyway - have any of you made the same knuckleheaded mistake? Did I totally ruin this batch? Will it make my brew taste like the turnstile at a NYC subway station?

Perhaps I just made things easier on the yeast that the recipe calls for at bottling time...

And, I still love my Refractometer. Can't blame that. I'll blame it on the medication I'm taking for this rotten cold.

Well if you introduced air to a near finished beer, there is a good chance oxidation will affect the taste of your beer. From what I have read, that is one of the off tastes that can't be fixed with aging.

You're probably fine--chances are that, unless you really whipped up the beer while stirring, you didn't oxidize it, since it's still pretty soon after primary fermentation completed and there's going to be a good oxygen blanket over your beer. Chances are you just gave the yeasties a little extra boost, if anything. Worst case scenario there might be a little oxidation, but I'd say you shouldn't worry too much about it.

I'm not worried about having oxidized the brew. It's a small opening at the neck of the Carboy and there is ample headspace filled with CO2. I only stirred at a slow speed for 15 seconds or so, and the MixStir keeps surface disruption to a minimum (unless you go for a deep cortex at high speed)

I'm more concerned about having introduced an Ammonia aroma. That yeast nutrient is pretty pungent stuff when it's boiling. Since all the sugar has already been consumed I don't know if the yeast will eat it. I'm just hoping it won't introduce off-flavored or aromas.

Sounds like you are fine then. When ever I use my stir stick its on full making a vortex in the bottle. That is what I pictured. It probably wouldn't hurt to raise your temp up a few to wake your yeasties up, but I bet they will make a good meal out of the nutrient.

Rdwhahb!

Update: The beer turned out fine. It is quite tasty and has no ammonia aroma or any detectable off-flavors.