If you're fermenting fruits and then distilling them, methanol is the first ingredient to boil out -- the first batch of distilled material will have nearly all

If you're fermenting fruits and then distilling them, methanol is the first ingredient to boil out -- the first batch of distilled material will have nearly all of the methanol in the entire run. The background amount of methanol might be very small (<1% in most fruits), but the distilling process necessarily concentrates it and could easily provide a lethal dose if you're working on large volumes.