I use filtered. Yes, I remember Peat was talking about looking out for allergens in your apple juice.Same for me with real apples, did you try filtered juice? I think they can be quite allergenic but not sure why exactly (it's a heavily pesticided fruit), some makes the inside of my throat itch.
I just use Martinelli's. Don't have a problem with it that I can notice.
In cold weather I'll heat it a little. That's most of the time where I live.