Rabbi Yishmael and Rabbi Yehoshua were traveling together. They were hungry and there was little to eat except for cheese manufactured by non-Jews. “Why can’t we eat the cheese?” asked Rabbi Yishmael. “Because we can’t,” answered Rabbi Yehoshua.
The Talmud explains that whenever the rabbis enacted a seyag, preventative legislation, to safeguard against the violation of Torah laws (such as intermarriage), they did not divulge the reason for the legislation for a period of twelve months and sometimes not at all. They were concerned that if they were to do so, people would argue that the stated reason no longer applies and would ignore the legislation. The rabbis’ decrees would then become like the flavor of the month, applicable today and discarded tomorrow.
Notwithstanding Rabbi Yehoshua’s refusal to divulge the reason, the Talmud offers a variety of explanations for the prohibition against eating cheese manufactured by non-Jews.
According to Rabbi Yehoshua Ben Levi and following him Rabbeinu Tam and the Ramban, the reason for the prohibition is a health concern. Idolaters used to leave milk uncovered in snake-infested areas and it was feared that snakes might inject poison into the uncovered milk.
According to Rabbi Chanina, and following him Rashi, the Ra’avad, the Ramban, and the Rashbah, non-Jewish cheese is prohibited because there is a concern that the milk of a non-kosher animal may have been mixed into the manufacturing process.
According to Rabbi Ada Bar Ahava, it is because cheese manufactured by idolaters is coated with lard. Even though the lard may be of insufficient quantity to impart a meaty taste to the milk and therefore not prohibited under the general rules of kashrut, nevertheless the prohibition against the consumption of food eaten by idolaters applies even in de-minimis proportions.
According to Shmuel and following him the Rambam, the Rif, and the Shulchan Aruch, the prohibition derives from the fact that idolaters used to make cheese by pouring the milk into the flask-shaped stomach of non-kosher animals, which exudes the rennet enzyme that solidifies milk into cheese. Generally, the presence of a cold non-kosher ingredient mixed into cold kosher milk does not render the mixture prohibited if it is batel beshishim – if it contains sixty times more of the kosher ingredient than the non-kosher ingredient, or if the mixture does not taste of the non-kosher ingredient. In this case however, the non-kosher rennet, which is a davar hama’amid, an ingredient with the capacity to turn milk into cheese, is so instrumental in manufacturing the end product that it cannot be ignored even in the minutest quantity.
Today, many arguments can be made as to why each of the above stated reasons does not apply. Non-Jewish milk is not left uncovered and so Rabbi Yehoshua Ben Levi’s concern is no longer applicable. Only the milk of kosher animals can be used in the cheese manufacturing process because the milk of non-kosher animals does not curdle and is therefore not a suitable ingredient. Today, lard is rarely, if at all, used in the manufacture of cheese. And today, cheese is rarely manufactured with the rennet of a non-kosher animal. Rather, vegetable or synthetic rennet is mostly used.
Yet, notwithstanding all of these arguments, cheese manufactured by non-Jews remains prohibited today by the halacha. Why?
First of all, it is important to note that not all the Rishonim prohibit the consumption of cheese manufactured by non-Jews. Rabbeinu Tam concludes that the only reason for the prohibition was the concern that if left uncovered, snakes would poison the milk. The prohibition was not universal. It only applied to communities residing in snake-infested lands and was not intended to apply beyond such areas.
Most other Rishonim disagree. They maintain that even though the reasons for the prohibition may not be applicable today, once the sages of the Mishnah or the Talmud got together and enacted a seyag, the prohibition does not automatically terminate unless repealed by another bet din. Now, in order to repeal the decree of an earlier bet din, the rule is ein bet din yachol levatel divrei bet din chavero ad sheyihe’yeh gadol mimenu mechachmah ubeminyan, which means the repealing bet din must be comprised of rabbis greater in wisdom and prestige than the rabbis who originally enacted the prohibition. Accordingly, since there are no sages today greater in wisdom and prestige than the sages who enacted that decree, the prohibition against eating non-Jewish cheese can never be repealed.
According to other Rishonim, once the stated reason for the prohibition no longer applies, a court of lesser wisdom and prestige can repeal the prohibition but the decree does not die automatically.
In view of the split between the Rishonim on this matter, the halacha is decided by the custom of each community. Communities that consistently followed the customs of Rabbeinu Tam may continue to do so, and for them non-kosher cheese is permitted.
As for us, the Rema rules that it is our custom to follow the opinion of the Rishonim that prohibit non-kosher cheese. Cheese manufactured by a non-Jew is permitted only if an observant Jew supervises the entire manufacturing process, including the milking process.
The prohibition against milk manufactured by a non-Jew is due to the concern that the non-Jew might have mingled the milk of a kosher animal with that of a non-kosher animal. Accordingly, milk manufactured by non-Jews in situations where there is a concern that milk from non-kosher animals may be mixed in is prohibited unless a Jew supervises the milking process.
Rabbi Moshe Feinstein rules that people in the United States who drink milk manufactured by non-Jews that has not been supervised by Jews should not be criticized. This is because U.S. food laws prohibit the mixing of the milk of kosher animals with that of non-kosher animals. Since this prohibition is enforced by penalties, including the threat of license revocation, one may rely on the probability that no manufacturer would risk it. Accordingly, while Rabbi Feinstein considers it praiseworthy to only drink milk supervised by a Jew, he finds grounds to permit the consumption of milk not so supervised.
Rabbi Feinstein also discusses whether the use of cottage cheese manufactured by non-Jews which, being soft, does not require the use of rennet as a solidifying agent, is permitted without Jewish supervision.