לע"נ הרה"ח ר' ישראל צבי בן הרה"ח ר' צדוק
לזכות ר' משה מרדכי בן חנה
There is a halachic axiom that a non-kosher ingredient which gives a product its form - דבר המעמיד - makes it non-kosher. In order to make milk congeal into cheese some use rennet which is derived from the lining of an animal's stomach [עור הקיבה] thus rendering it unkosher. Rav Tzvi Pesach Frank ztz"l [Rav Ovadiah referred to him in his sefarim as מופת הדור - the phenomenon of the generation] was asked about rennet made from powder [or pills] composed of the lining of an animal's stomach together which natural ingredients where the majority are the natural ingredients. So we have a a דבר המעמיד which isn't kosher but is only a minority. May we eat this cheese???
According to the Shibolei Haleket when the עור הקיבה completely dried out and has no more moisture one may use it and it is no longer considered meat. The Rema [Yo"d 87/6] rules this way as well. And even though the Shach [87/33] writes that לכתחילה one may not rely upon this, R' Akiva Eiger [207] explains that this is only in an instance where there is not 60 times the amount of rennet to nullify it in which case we are worried that it didn't completely dry out [one could also suggest that when it comes to powder there is no concern that it didn't completely dry out] but when there is 60 times it is nullified even לכתחילה.
However the Noda Bi-yehuda [Yo"d 26] explained that this only applies to the עור הקובה of a kosher animal which is not inherently unkosher but only when it is mixed with milk. But עור הקיבה of a trief animal renders the milk nonkosher even when there is 60 times. Others differ [see Pischei Teshuva 87/21].
In our case we may permit the cheese because it is זה וזה גורם - there are two factors in the forming of the cheese, kosher and nonkosher, and we rule that זה וזה גורם is permitted. One might argue that זה וזה גורם is only permitted בדיעבד, here the amount is so minute that it is only a חצי שיעור and this חצי שיעור is no longer fitting to be eaten by a dog so it loses it's status as nonkosher material even if the animal is treif [according to those who argue with the Noda Bi-yehuda].
To summarize - we have a זה וזה גורם with a חצי שיעור that has dried out and lost its original form.
KOSHERRRR!!!!
[I saw on a kashrus website that such cheese is nonkosher. I guess Rav Frank didn't see the psak of the website...:-)]
