I am a little bit confused - when should it be "such a" and when only "such" is applicable? Does it anything to do with the "countability" of the object?
Oh, I thought it was always uncountable. Guess I just learned something new about English grammar :) thanks for correcting me.
Anyway, if juice is not necessarily uncountable I don't know why Jan's answer wasn't accepted. I can only say that "...such juice" was. Maybe it has something to do with context...