Sourdough

Hi Chef!  First post for me!  Just want to start by saying what an awesome resource this whole website is.  I never really loomed at the forums but I follow the podcasts closely, and even watch videos sometimes.

I have a question about sourdough, which was brought up again while listening to episode 34.  You explained that you have to throw out some of the dlugh to get rid of the acid, other places i beleive you said to pour of alcohol.