My last batch (extract IPA) had what I would consider a clear oxidized taste (wet cardboard). Aside from the fact that it might have oxidized from the normal sources (i.e. splashing the wort at a high temp), are there any other causes? I've read that use of old or stale steeping grains could cause this as well. Unfortunately, I live in an area where there are no LBHS (Japan) and must "stretch" out what I have on hand. What I steeped in the recipe was probably several months old, though not milled prior to brew day. Not much info out there on exactly how to tell if steeping grains are beyond their shelf life.
Most steeping grains will store for 18 months if kept dry. If you order more than you need for an order, just take the balance and put them in a zip lock bag. Brian
Wouldn't old grains be rancid? It's a distinctly different odor/flavor, imagine opening a jar of peanuts that have been setting on the shelf for a year, or old almonds. Wet cardboard really sounds like hot-side oxidation - I've tasted it at our local homebrew night at the supply store (but thankfully, never in my own brews!).
How big is your boil? If you have a small boil and are adding it to water to get to your full volume. Your problem could be with the water not the wort or grains. What sanitizer are you using? Mixing a no rinse sanitizer too strong will effect the tast of your brew.
I typically do a 2.5 gallon batch with a 3 gallon boil (not requiring much of a topoff). I've also moved the stored grains into the fridge. Prior...they were just kept sealed and dry in zip lock bags. Just finished a brew using .5 lb of 3 month old Crystal 30 that were milled just prior to steeping. The grain tasted fine after milling...we'll see how it goes.
