The OU accepts whey from cold non-kosher cheese production, provided that the cheese is made with kosher rennet. However, there is a disagreement among poskim, regarding whey that was made with animal rennet. Teshuvos Chasam Sofer (Y.D. 79) assumes that the rennet acts as a ma’amid on the whey, and he therefore writes that whey that was hu’amad with non-kosher rennet is assur. However, Shevet HaLevi (4:86) argues that the rennet is not ma’amid the whey. Igeros Moshe (Y.D. III:17) points out that commercial rennet is nifsal mei’achila. Some have questioned whether the rennet is really nifsal, since although it is soaked in acid, the acid is later neutralized and final product is not necessarily nifsal. Furthermore, Rav Belsky zt”l would quote the Achiezer (Y.D. 11) that an ingredient that is inedible so long as it is omeid l’kach (this is how it is intended to be used), never considered nifsal. For example, although se’or (sour dough) is inedible it is not considered nifsal, since it is omeid l’kach.
The policy of the OU is not to accept whey that was made with animal rennet. Additionally, non-kosher lipase or cultures may not be added to the whey. Although the lipase and cultures will surely be batel b’shishim, but since they could affect the taste of the whey they would be like a davar hama’amid. Additionally, this would be bitul issur. However, the keilim used to process whey which was made with non-kosher rennet, lipase or cultures will not need kashering. Until now. we have been discussing only cold cheese whey. However hot cheese whey, in which the whey is cooked with the cheese, has many more complications that will be discussed in a later article.
Although Chazal forbade gevinas akum, because we are choshesh that it was made with non-kosher rennet, still this chashash is a special gezeira of Chazal, which is only in regards to the cheese. The whey itself is permitted, provided that we have regular supervision that they are using only kosher rennet. There is no requirement that the mashgiach must add the rennet or even watch the cheese being made, in order to permit using the whey.
Shulchan Aruch (Y.D. 112:14) writes that one is permitted to buy “kutach” from a non-Jew. Kutach is a dip that is made from, among other things, salt, whey and bread crumbs. The bread crumbs, although they are pas akum, are permitted, since they are batel b’rov. But why is the whey from chalav akum permitted? Rabbeinu Tam explains that since chalav tamei does not separate to form cheese, a non-Jew would not add chalav tamei to his milk if he is planning on making cheese. Bach (Y.D. 112:11) explains that even if the whey might contain a small amount of chalav tamei, still the kutach is permitted, since the whey is completely absorbed. The miniscule amount of chalav tamei will be batel in the kutach. Bach explains that in this respect kutach is more lenient than butter. Butter from non-Jews must be boiled, to remove any pockets of milk that might
remain inside the butter, but kutach is thick. It does not contain any pockets of liquid and is therefore permitted without cooking.
Since we explained, based on Chasam Sofer, that whey made with non-kosher rennet is not kosher, why were the poskim not concerned that the whey used to make kutach might have been separated using non-kosher rennet? Why were they only concerned about chalav akum; why were they not also concerned about the type of rennet that was used?
One possible answer is based on what was explained before from the Bach. Since in this case, the whey is completely absorbed into the kutach, it does not have its own consistency. Whatever ha’amada the rennet accomplished in the whey is lost when it is blended into the kutach. Since the whey was only assur because of the ha’amada, once that ha’amada is gone, it reverts back to being mutar.
Another example of this concept involves COW (Condensate of Whey) water. COW water is the evaporated water that is removed from whey. This water that separates, although it may be pure water, remains milchig (chalav d’rabbanan) because it was originally a component of the milk. What if the whey was made with non-kosher rennet or lipase? Would the COW water that separates from this whey remain assur as well? Rav Belsky zt”l said that if the COW water is pure enough that the davar hama’amid has no effect on the properties of the water, then the water is permitted. The rennet only makes the whey assur so long as p’ulaso ni’keres (its effect remains evident). Once the effects of the rennet are lost, the whey reverts back to being permitted.
by Rabbi Eli Gersten
Recorder of OU Pask and Policy