Chullin Daf 112 צולין דַף 112

Abaye said that the halachah is that fish which was placed hot onto a meat plate may be eaten with כותח (because it is נ"ט בר נ"ט). However, if one cut a צנון – radish with a knife with which meat was cut, it is prohibited to eat with כותח, because אגב חורפיה בלע – due to its sharpness, it absorbs the meat residue on the knife’s surface. Rashi adds that even if no residue remains, the radish’s sharpness, coupled with the knife’s pressure, causes it to absorb a strong meat flavor from the knife. This only applies to a sharp food such as a radish, but if one cut קישות – squash with such a knife, גריר לבי פסקיה ואכיל – one may simply scrape the surface area of the cut and eat it with כותח, because its sweetness prevents it from absorbing the meat flavor. קילחי דליפתא – turnip stalks cut with such a knife are permitted with כותח, because their sweetness neutralizes the meat flavor. Beet stalks cut with such a knife are prohibited with כותח, because they are sharp. However, if one alternated between cutting beet and turnip stalks, the turnips’ sweetness weakens the meat flavor to the extent that even the beets may be eaten with כותח.

A shechted pigeon once fell into a jug of כותח, and Rav Chinana brei d’Rava of Pashronya permitted it. Rava commented:  מאן חכים למישרי כי האי גוונא – who is wise enough to permit a case like this, if not Rav Chinana brei d’Rava of Pashronya? He holds that Shmuel’s rule, that מליח הרי הוא כרותח – something salted is like something hot and transfers flavor, only applies היכא דאינו נאכל מחמת מלחו – where it is so salty that it is not eaten due to its saltiness until it is rinsed with water. Therefore, since כותח is eaten (and is not that salty), it does not transfer flavor to the pigeon. This lenient ruling only applies if the bird was raw, but if it was roasted, the surface area which contacted the כותח absorbed its flavor and must be peeled away. If the roasted pigeon has cracks in it, it is entirely forbidden, and peeling does not suffice. Similarly, if it was seasoned with spices, the meat is softened and absorbs the כותח flavor throughout.

Rav Nachman said: דגים ועופות שמלחן זה עם זה אסורין – fish and fowl which were salted together are forbidden, i.e., the fish are forbidden because they absorb blood from the fowl. The Gemara clarifies that this cannot refer to salting them in a כלי שאינו מנוקב – an unperforated vessel, because even birds salted with other birds in such a כלי would be prohibited, because although meat does not absorb blood while emitting it, it can eventually reabsorb the blood after it ceases to exude from the meat. Rather, Rav Nachman’s ruling is בכלי מנוקב – with a perforated vessel. The fish are nevertheless forbidden משום דרפו קרמייהו – because their skin is soft, so קדמי ופלטי – they hasten to emit their blood, whereas bird meat is קמיטי – tight, and releases its blood more slowly. Therefore, after the fish cease emitting blood, the birds continue to release blood, which the fish absorb, prohibiting them.