Q. Why must cheese be certified kosher for Pesach?
A. Shulchan Aruch (Orach Chaim 442:5) writes that cheese that was made with wheat vinegar must be destroyed before Pesach. Mishnah Berurah explains that this is true, even if the vinegar is less than one part in sixty and does not give any taste to the cheese. Since the vinegar helps form the cheese (maamid), the regular halachos of bitul (nullification) do not apply. The same holds true for the bacterial cultures that are used to form the cheese. If the cultures were grown on glucose derived from chametz, the cheese may not be eaten on Pesach. Kosher l’Pesach cheese is made from kosher l’Pesach cultures.
This column comes from OU Kosher’s Halacha Yomis dedicated in memory of Rav Chaim Yisroel ben Reb Dov HaLevy Belsky, zt’l, Senior OU Kosher Halachic Consultant (1987-2016). Subscribers can also ask their own questions on Kashrus issues and send them to firstname.lastname@example.org. These questions and their answers may be selected to become one of the Q and A’s on OU Kosher Halacha Yomis.