Originally Posted by jtejedor
I think super stressed yeast can release these flavors. I lost a few batches using super old yeast that I tried to revive. Are you consulting yeast calc? I know sometimes the starter size estimates can be high but I have been having much better luck going by its numbers.
I rarely re-use yeast, and when I do I make sure to wash it and pitch the proper amount. I always go by the yeast-pitching calculator at mrmalty.com as well.