I have always used apple cider vinegar (Organic, Raw, Unfiltered, "with the mother" such as Bragg.) in my flushes as a substitute for apple juice in the 4-5 days leading up to the olive oil. I drink it fairly strong, perhaps 2, maybe even 3 tablespoons of ACV in a glass of water, and generally go thru about a quart of ACV over the 4-5 days. I believe this is very agressive in stripping the hard outer coating off of the stones and in my belief even beginning to melt many of them down into something more sludgy. I believe it would be difficult to be quite so aggressive with apple juice and it allows you to eliminate the "sweet".