647. Separating Different Types of Food
Shabbos 8:13
One who separates undesirable material from food is liable even if he only uses one hand. One who separates beans from their hulls is liable because the hulls sweeten the beans when they are cooked together. Therefore, it is considered taking undesirable material from food, for which one is liable. If a person takes food from undesirable material by hand and puts it aside for later use - even for use later on that same day - he has separated for the purpose of storage and is liable. If a person had two types of food mixed together in front of him, he may take one from the other and put it aside for immediate use. If he separated and put it aside for later use – even for later on that same day - he is liable, such as one who separated food in the morning intending to eat it in the afternoon.
Shabbos 8:14
If a person filters the dregs from wine, oil, water or any other liquid using a utensil designed for this purpose, he is liable so long as he removed the dregs from an volume of liquid equal to that of a dried fig. One may filter wine that doesn’t have dregs or clear water through a handkerchief or a wicker basket in order to further enhance their clarity. Water may be poured over wine dregs in order to remove any wine residue from them. Similarly, one may put a raw egg in a mustard strainer in order to refine it. If a person mixed mustard on Friday, he may stir it on Shabbos either by hand or with a utensil in order to make it fit for use. Similarly, while wine is still fermenting one may pour it from the barrel together with the dregs over cloths (that will strain it). Since the dregs have not yet been fully separated from the wine, the whole thing is still considered one item. This is also true of mustard and any other such substance.