Chap. 21 Mishna 3
Cleaning up on Shabbos. We distinguish between food scraps that are still edible (and thus prepared for Shabbos use) which we may move with our hands, and inedible scraps (whether by human or animal, which are muktzeh) which we move indirectly because we’d rather not touch them. Indirect removal of muktzeh can be accomplished by shaking off the table cloth or lifting the scraps from the table in an atypical manner. Bread is a special category because it represents our blessings from Hashem. We must dispose of it respectfully. We avoid using a sponge in a way that will lead to wringing out the liquid, a forbidden labor on Shabbos.
Chapter 22, Mishna 1
We may not squeeze juice from fruit for drinking on Shabbos, nor drink juice that seeped out by itself from fruits that are generally designated for juicing. We may squeeze a bit of lemon onto a solid food, however, since this is not juicing for drinking, but rather “moving” a bit of food from one location to another. If fruit scattered on ground in courtyard, we may gather some for eating that Shabbos, but not to clean up the all the fruit from the ground, which is a weekday activity.