Separation is defined as removing the dross from the desired items: Shabbat 138a
Permitting Separation if it is done by hand: Shabbat 74a
Permitting Separation if it is done for immediate use: Shabbat 74a
Permitting Separation if it is done by removing food from non-food: Shabbat 74a-b
Food from Food: Shabbat 74a, 139b-140a
Separation where the food would be eaten even without the Act: Shabbat 109a, 139b
Possibly Related Melachot
Winnowing: Shabbat 73b-74a Sifting: Shabbat 73b-74a
The Minimal amount is a Dried Fig Amount for separating curds from milk: Shabbat 95a, Pesachim 65a
Separating Curds from Milk is a Biblical prohibition: Shabbat 95a, Pesachim 65a
Separating Turmus-beans from inside their shells: Shabbat 74a-b
Using a strainer: Shabbat 137b, 138a, 139b-140a, 140b
