Cooking Meat and Dairy in the Same Oven: The Halachic Issues
Guest post by Rabbi Michael Broyde*
Michael Broyde is a law professor at Emory University, was the founding rabbi of the Young Israel in Atlanta and is a dayan in the Beth Din of America.
One of the most frequently asked kashrut questions deals with the procedure for cooking meat and milk in a single oven. This short article will address the halachic issues involved, explain the different opinions found in halacha, and recommend a practice to follow.
I. Aroma and Steam
The Talmud (Pesachim 76b) recounts a dispute between Rav and Levi as to whether aroma (in Hebrew, rei’ach) emitted from food is halachically significant or not — whether kosher food cooked in the same oven at the same time as non-kosher food becomes non-kosher because of the aroma. Rav states that such aroma is significant and thus the food is not kosher, and Levi rules aroma not to be problematic and the food kosher. While there are a smattering of rishonim who follow the ruling of Rav (see Tosafot s.v. orsa), most accept that the halacha is like the approach of Levi and that aroma is not significant and that such food is kosher; see Rambam, Maachalot Asurot 15:33; Rif, Chulin 32a and Rashi, Pesachim 76b s.v. amar lecha. However, they accept that aroma is only not significant post facto (bedi’eved), and that even Levi accepts that one may not deliberately cook kosher and non-kosher food in the same oven at the same time. The Shulchan Aruch (Yoreh Deah 108:1) accepts this approach, and permits aroma post facto, but prohibits this conduct initially (lechatchila).
Rama adds that the rules governing kosher and non-kosher foods cooked together in the oven are identical to those governing dairy and meat items cooked together in the oven. In addition, he states that the practice is to be strict in each of the following circumstances:
- Passover food may not be cooked with chametz;
- Spicy food that is not kosher may not be cooked with kosher food;
- Even if the oven is well ventilated, the foods may not be cooked together;
- Ideally, one should not even cook a parve item with meat in the oven when one’s intent is to eat the parve item with dairy.
However, so far we have only discussed the issue of aroma. The Shulchan Aruch (Yoreh Deah 92:8) adds, based on a responsum of the Rosh (20:26), that when two items are cooked in the same oven, there is another problem — steam. Steam (in Hebrew, zei’ah) rising from one item to the other is a halachic problem, and that “if one places a pan of milk below a pot of meat, the steam [from the milk] rises into the meat and renders it non-kosher.” Unlike aroma, which is permitted post fact (bedi’eved), the Shulchan Aruch rules that dairy steam actually makes a meat item completely non-kosher.
II. Meat and Milk in the Same Oven
The crucial question is why the Shulchan Aruch rules that “steam” arising from milk is of such significant halachic concern that it actually renders the meat above non-kosher, but aroma — at least post facto — is permitted. This question is not some abstract talmudic question, as the answers to it provide the various opinions as to when one may cook meat and milk in the same oven.
Three famous answers are provided.
- The Aruch Hashulchan (YD 92:55) argues that steam is only of halachic concern when one cooks in a very small oven that is poorly ventilated; in our modern ovens, only aroma is a significant halachic problem and only when the meat and the milk are in the oven at the same time. Thus, according to Aruch Hashulchan, one may cook meat right after milk in our modern large ventilated ovens, so long as the oven is clean (as a clean oven eliminates the problem of aroma from one food to another). This was a widespread custom in Eastern Europe a century ago, and Rabbi Hershel Schachter of Yeshiva University tells people that it is completely proper to follow this approach in their own house.
- Rabbi Moshe Feinstein (Iggrot Moshe YD 40), following the suggestion of the Pri Megadim, argues that steam is always halachically significant when it emerges from liquid foods. However, it may be assumed that solid foods do not produce significant steam (unless one clearly observes to the contrary). Combined with Rama’s assertion (YD 92:8) that steam is not a problem when the pot producing the steam is covered, Rabbi Feinstein counsels that one may cook meat immediately after milk once the oven cools down, if neither are liquid foods or one of them is covered. Rabbi Aharon Lichtenstein of Yeshivat Har Etzion encourages people to follow this practice (or to wait 24 hours between meat and milk use of the oven).
- Rabbi Yitzchak Yaakov Weiss (Minchat Yitzchak 2:50) maintains that the distinction between aroma and steam is hard to discern and whenever possible a person should have two ovens, one used exclusively for meat and one used exclusively for milk. Rabbi Weiss rules that there is a genuine halachic concern that steam is left in the oven from a meat item which is absorbed by a dairy item, rendering the second food categorically non-kosher or that steam enters the walls of the oven which have absorbed both meat and milk flavor, thus rendering the oven and any food cooked in it non-kosher. Absent two ovens, one must kasher the oven between use or double wrap either the meat or the dairy items. Rabbi Feivel Cohen, the author of the Badei Hashulchan (in YD 92:180), adopts this approach and also requires separate grates for the oven (a requirement which Rabbi Feinstein explicitly, and the Aruch Hashulchan implicitly, rejects).
My own practice is to try to follow the approach of Rabbi Feinstein whenever possible, although the generally permissive approach of the Aruch Hashulchan is acceptable. It is not necessary even to strive to accept the approach of Rabbi Weiss and have two ovens.
In practice, the approach of Rabbi Feinstein means that one must decide whether one’s oven is meat or dairy. If one decides that one’s oven is a meat oven, all meat items may be cooked in it without hesitation. Dairy items, however, may only be cooked in the oven if they are solid foods (such as kugels, casseroles, and, perhaps, even pizzas) or, if they are covered liquids.
As an alternative, if one does not want to cover the dairy liquid when it is cooked in the meat oven, one may either kasher the oven by setting it to its highest temperature for an hour or wait 24 hours from the last time the oven was used for meat, and then cook the dairy item uncovered.
* This article was first written in 1994 or 1995 and shared with the Young Israel members at that time and was now slightly revised. The original article reads in the thank you section “My thanks to Rabbi Howard Jachter, whose forthcoming article on this topic inspired this research and a debt is owed to an excellent article on this topic by Rav Shmuel David in Alon Shvut 130.” Rabbi Jachter’s excellent article was published in the Journal of Halacha and Contemporary Society, Fall 1996, and like all of his work, really is stellar, even with the passage of time.
 Three other approaches are worth mentioning. Mishkenot Yaakov (YD 34) solves this problem by positing that the discussion of steam found in the Rosh and Shulchan Aruch is mistaken, and steam is of no halachic concern. His approach is a very minority approach and should not be followed. Chavat Da’at (Biurim 92:26) rules that the problems of steam is limited to cases where one item is on top of the other; in cases where the two items are side to side, there is no problem of steam. While a number of authorities do accept this approach (see Badei Hashulchan 92:166), and the result of this approach would be that one could cook meat after milk in the same oven, just on a lower rack, the common custom is not to follow this approach. Aruch Hashulchan (92:55) accepts the assertion of the Rosh that the discussion of steam is limited to cases where one of the two pots is cold.
 How one kashers an oven is a famous dispute between Rabbi Soloveitchik and Rabbi Feinstein. Rabbi Soloveitchik ruled that one need only turn an oven to its own highest temperature for an hour or two in order to kasher it, whereas Rabbi Feinstein maintains that in order to kasher an oven one had to raise the temperature of the oven to 900F by using either a blow torch or charcoals. The approach of Rabbi Soloveitchik is well defended by Rabbi Mordechai Willig, in the OU’s Kashrut journal Mesorah 4:83-96, and that is the approach accepted by this writer.