I brewed an oatmeal stout, 10 gallon, and I realized too late that the hops I used for bittering may have been too old-when they came to the surface they were brown instead of green. Now my stout is very sweet and I can’t stand it. I can get away with calling the first keg a milk stout but I really want to enjoy the other keg. Can I boil an oz of fresh Challenger in plain water and add to the second keg? I’ve always been against trying to "fix’ a beer but now need your sympathy and help. I will finish the first keg of overly sweet beer as a self punishment but lease help me with the second one.
Add a little carbonation if appropriate, that could help cut the sweetness (a bit)
Don’t boil hops in water, boil them in a little DME, then add that to the keg. If you’re worried about residual sweetness from the DME (since it’s already too sweet) then add a little bit of yeast to it after it cools and let it ferment out, then add it. You should be able to add some bitterness with less than a quart of liquid and it should change the flavor too much. If you are really cautious you can use a small amount of specialty grains to mimic the stout. But don’t boil hops in plain water, it doesn’t taste right.
You might look at the hop shots available from NB too, I haven’t used them and you still have to boil, but there will be less loss from the hop material. I don’t know if those can be boiled in plain water.
I think you can keg-hop with a high alpha and help it out. Try a tea-ball. It might foam a bit so be quick!
I’ve got to disagree euge, you’re not going to pick up much (if any) bitterness at keg temps.
Oh well… 
This never happened
Both Morebeer and Nikobrew have an iso-hop bitterness extract you can add to increase bitterness w/o boiling.
Just a thought… Draw a pint & add some Bourbon or Whiskey to it. Maybe start with a Tablespoon & go from there. I do that with my Sweet Stout, plus I add vanilla but that sweetens it up more. I’ve also blended Stouts with IPA’s in the glass. It’s an interesting flavor. Course when I was in grade school I loved Peanut butter, pickles & mustard sandwiches so you be the judge. :o Cheers!!!
ABSOLUTELY this. I saved a 10g batch of underbittered Anchor Porter clone. When scaling up, I forgot to double the bittering charge. Not cheap but very effective. I planned to underbitter the next few batches so I could use the rest but never did…
It was mentioned to blend in some IPA. Pick up a six pack of some decent IPA and blend into the stout. I think you’ll be pleasantly surprised by the results.
That’s good to keep in mind, but $27 vs. $2, and you need to use it in 2-3 months . . . actually it says it will “stay fresh” for 2-3 months, but it also says that it will not lose potency over time. :
Has anyone used it more than 3 months after opening it?