795. Winnowing and Selecting

Shabbos 21:16

If grapes or olives were crushed on Friday, the liquid that flows from them on its own on Shabbos is permitted. Similarly, if honeycombs were crushed on Friday, the liquid that flows out on its own on Shabbos is permitted. There was no reason to enact a preventive measure as these things were already crushed before Shabbos began.

Shabbos 21:17

Winnowing and selecting are primary forms of labor. Even though one is permitted to remove grain from the husk with his fingers, he may only blow on them while holding them in one hand. One may not use a tray or a pot that is divided into compartments out of concern that one may come to use a sifter or strainer, which would render one liable. Filtering dregs is a subordinate labor of selecting or sifting. Even though one may filter clear wine or water through a handkerchief or a woven basket, he may not make a recess in the handkerchief to catch the dregs as one would do during the week. This is a preventive measure against the possibility of coming to filter dregs with an actual filter. It is likewise prohibited to hang a filter as one does during the week out of concern that one may come to filter dregs. Curdling milk into cheese is a subordinate labor of separating. Therefore, even though one may put sesame seeds and nuts into honey, he may not mix them into a block with his hands (which is comparable to making cheese out of milk).