What does freshly juiced apple juice separate into?

Question

When I use my juicer on apples, I obviously get the juice out one side, and the dry pulp out the back. But when I let the juice sit for a few minutes, the juice separates into a foamy content on top, a clear/amber colored juice in the middle, and a 'sludge' on the bottom. What is the foam and 'sludge'?

Answer 1

The sludge is suspended apple fiber and juice; the foam is juice mixed with air.