I have recently brewed at APA and the IBUs have come out a little on the low side. I would like to increase the IBUS slightly. I was thinking of making a hop tea and adding it straight to the keg. Has anyone tried this? What are the things i need to consider?
The easiest way to do this post boil/fermentation would be to get your hands on some isomerized alpha acid extract. Add it dropwise until the bitterness is where you want it.
The thing about hop teas is that they contain negligible bittering levels. They do, however, contain a ton of hop flavor & aroma. If you're looking to boost IBUs but not flavor and aroma, a tea is not the way to go. In order for hops to bitter a beer, they need to be boiled to isomerize the alpha acids. Hop teas are typically made by steeping the hops in hot (not boiling) water. Doing this allows you to extract hop flavor and aroma without getting any bitterness.
I recently did this on an IPA I brewed. When I finished sparging, I drew off one pint of the wort and brought it to a boil. As soon as it hit the boil, I killed the flame and let it cool to about 190F, then poured it into my French press which contained about 3/4 oz of centennial pellets. I allowed this to steep while my kettle came to a boil. When the kettle reached a boil, I pressed the hop tea off into a sanitized jar and set it aside. I then added the hops from the French press to my kettle, using them as part of my 60 minute addition. This allowed me to pre-extract the flavor & aroma from bittering hops. The tea, however, contained little-to-no IBUs.
Now, if you just want to boost IBUs, you could take some bittering hops and boil them for an hour, then add this to your beer. It's probably a good idea to add some DME to the water to get it to about 1.025 or so to create a wort with chemistry that will allow for better hop utilization than you'd get with plain water. Yes, hop utilization goes down as SG goes up, but I've read that the pH and other minerals you'll get from adding some DME will work better for you than plain water. If you do this and use DME, you'll be adding fermentables, so you should account for that. If you're bottle conditioning, you could plan to prime with DME and boil it for an hour with some hops (remember to account for boil-off).
All that said, I think the easiest way to boost IBUs is probably to just use some hop extract. I've never used it, but it exists for just this reason.