when putting part of the animal stomach into milk to produce cheese isn't there a problem of busor be'chuluv?
and even if we would say that it is butel beshishim, isn't there the problem of ein mevatlin isur lecetchila ?
noah zablotsky, brooklyn ny USA
You're right on both counts: there is a problem of Basar v'Chalav and there is a problem of nullifying Isur. One is not allowed l'Chatchilah to use the Or ha'Keivah to make cheese because the Or may impart flavor of meat to the cheese (Shulchan Aruch YD 87:11). (The fact that the Or ha'Keivah is creating the cheese through enzymatic action is not a problem of Ma'amid, because the Ma'amid here is not something which is intrinsically Asur. See Beis Yosef YD 87 in the name of the Ran.)
The Rema says that if the Or ha'Keivah is dried up completely it is no longer considered Basar and may be used to make cheese. The Shach argues and says that l'Chatchilah one should not do this (presumably out of concern that it is not completely dried up). (Rebbi Akiva Eiger says that this applies when there is not sixty times as much milk as the Or ha'Keivah; when there is sixty times as much milk and the only concern is Ein Mevatlin Isur l'Chatchilah, then it is permitted.)
This is not a Psak Halachah