R Michael Broyde / 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).

Meat and Dairy In One Oven

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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:

  1. Passover food may not be cooked with chametz;
  2. Spicy food that is not kosher may not be cooked with kosher food;
  3. Even if the oven is well ventilated, the foods may not be cooked together;
  4. 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.[1]

  1. 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.
  2. 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).
  3. 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[2] 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).

III. Conclusion

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.
[1] 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.
[2] 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.

About Michael Broyde

28 comments

  1. Question: Liquids that become solids, and are unlikely to produce “significant” steam, e.g. eggs, a milchig custards made with eggs (e.g. quiche), cakes (e.g. cheese cake); would these need to be cooked covered in an oven according to Rav Feinstein?

  2. Meir says.
    Kashering an oven however hot you make it is really today impossible. Most are made with ‘cast iron’ which you can even use a blow lamp and never get red or white hot. That is the translation of ‘libun’. There are two ways to get rid of an ‘issur bolua’. Either take it out or burn it out. Kbolo kach polto is only on taking it out, not burning it out. If it doesnt get red or white hot the issur stays in.

  3. R. Broyde-
    “How one kashers an oven is a famous dispute between Rabbi Soloveitchik and Rabbi Feinstein.”

    since the oven is “hetera bala”- this machloket would seem to not be relevant and all would agree that libun kal should be sufficient?

  4. I also have a question on the logic of steam vs. aroma:

    Of the two, in practice aromatic particulates that arise from cooked food, are more likely to transfer “tam” than steam (which by definition is gaseous water). So it is hard to understand why we would be more lenient on aroma over steam?

  5. Interesting is how the mtziut of ovens and condensation and odors(past or present) is either regarded or disregarded under the various theories. Reminds me of R’HS’s statement that all the rabbis should get together and change the application of the rules of absorptions for stainless steel based on it’s physical difference from old steel used for utensils years ago.
    KT

  6. 1. Regarding aroma, R. Broyde neglects to mention that the entire issue is only when the meat and dairy are being cooked without the separation of the walls of a pot/pan. Whenever each is cooked in its own utensil (even uncovered), there is no issue of reicha (108:2).

    2. Regarding steam, R. Aharon Kotler is known to have held that there is no problem of steam in our ventilated ovens. R. Yitzchok Koslowitz, rosh chabura in BMG makes the case that steam is only an issue in areas such as a מחבת (the case the Rema mentions in 108:1), and that our ovens are not an issue at all. R. Yitzchak Abadi told me so as well. A sefer that was recently published in Lakewood that has haskamos from various ‘big names’ rules this way as well, although R. Belsky, in his haskama, says that he disagrees with the ruling – not for halachic reasons, but because “you can’t discount the well-established minhag the women have to kasher between meat and milk” (paraphrased). OTOH R. Koslowitz said over that R. Shlomo Miller said he never heard of such a minhag. I forget the name of the sefer, I can post it later.

  7. Meir says
    The sefer zer hashulchan similar to the badai hashulchan says if you cook an egg in a milky or meaty pot you wont be able to tell the difference.
    Therefore all these dinim shouldnt apply today.

  8. This post reminds me that when we were learning some issues of Yoreh Deah one summer in teh Morasha Kollel, R. Willig disussed the outlier view of the Ra’ah that the gemara’s statement of gazru eino ben yomo atu ben yomo only applies to issurah, not to hetterah, and acc. one only needs to have one set of dishes and cooking utensils, so long as you are careful to make sure the utensil is an eino ben yomo. The Ra’ah was noheigh this way, to the great consternation of his talmid the Ritva. R. Willing commented, “Ms. Ra’ah must have been a great balabusteh! (i.e. to be able to keep straight which item was ben yomo and which not.)

    This entire discussion presumes that there is no be’ein in the oven. Given the number of spills that routinely occur in cooking, this is not always an easy thing to guarantee. While strictly speaking having two ovens is not a halakhic requirement, on a practical level it makes life much easier, and avoids problems caused by a be’ein. <Hehchaham einav be rosho.

  9. R’ Tal,
    there’s a huge difference between making life easier and kids coming home being taught that the practice of their grandmothers’ from time immemorial is problematic. Any indication that there was any time in Jewish history that 2 ovens (or perhaps 3 or more ) were standard?(I don’t know the answer)
    KT

  10. I wonder why Rabbi Broyde put the view of the Aruch Hashulchan in the footnotes and not in the text? Otherwise, excellent article.

  11. Larry Lennhoff

    We use the self clean cycle to kasher the oven between milk and meat. I may show my wife this article and suggest we only do that when there are spills in the oven, and otherwise adopt RMF’s position. I think there are plenty of Jews who cannot afford two full ovens (either cost or space), and who may not want to use an oven for meat and a toaster oven for dairy.

  12. meir says
    One should not ‘kasher’ from milk to meat or vice versa but make it treifa first.

  13. there’s a huge difference between making life easier and kids coming home being taught that the practice of their grandmothers’ from time immemorial is problematic.

    JR, yes and no. If by problematic you mean, halachicaly suspect, you have a point. But if by problematic you mean, likely to create problems, then yes our grandmother’s practice (as to which poverty and other circumstances left them no choice) was problematic. I once read that years ago, where kitchens were much smaller and more cramped, there were many more spills and shaylos about accidental mixing of milk and meat than today.

    And, of course, you have to take both sides. Our grandmothers may have had only one oven and smaller kitchen space, but they were home all day and had the time and focus to be on top of what was happening in the kitchen, not to mention the yiras shomayim to ask a shayloh when needed.

    By having one oven, you are putting the user (generally the housewife) to the burden of always making sure that the oven is clean when using. If that is all you have, so be it. But given that women today have many more demands on their time, there is an argument to be made for erring on the side of safety. Practicality has as much to do with halakha le maaseh as the theoretical halakhah.

  14. R’TB,
    The former
    KT

  15. “there’s a huge difference between making life easier and kids coming home being taught that the practice of their grandmothers’ from time immemorial is problematic. Any indication that there was any time in Jewish history that 2 ovens (or perhaps 3 or more ) were standard?(I don’t know the answer)”

    my grandmother only cooked meat in the oven and double-wrapped milchig.

  16. Despite the MINHAG not to kasher from meat to dairy, R. Ovadya Yosef and many others have no problem in this case. I believe that in the article published by R. Jachter this is addressed- although the simple answer is either that the oven is not the keli in this scenario (rather the box in which something is being cooked)- or that kashering the oven if a chumra- as the halacha is really like the Arukh Ha-Shulchan- as one who opens an oven today will quickly realize that there is no zeah going to the ceiling and then raining back down on the food.

  17. Larry Lennhoff

    Meir:

    Is an oven a utensil in the same sense that a knife or fork is? Particularly built in ovens as are common nowadays?

  18. Tal Benschar

    Actually, I question whether the Minhag cited by Meir applies here at all. Self cleaning was not created to help us kasher ovens — it was created as a convenient way to clean out the oven. If someone uses this feature, then it is simply a convenient result that the oven is now kashered halakhically as well as clean. No reason the person should not be able to treat it as kashered.

    This is similar to kashering utensils for Pesach, which the Magen Avraham says you can do and then switch from meat to milk. IOW, as long as you are doing it for another purpose, then if it happens to be kashered, then the minhag does not apply.

    (Anyone know of poskim who discuss this?)

  19. The sefer I mentioned above is called מאור החיים, written by a ר’ חיים שטייער in 2009. The relevant portion is on page פז which reads:

    לאפות בשר וחלב זה אחר זה כששניהם מגולים, תלוי במחלוקת גדולי הפוסקים, ולמעשה יש להקל לאפות באופן זה בלבד שידקדק ליתן התבנית* ע”ג מקום נקי לגמרי

    He cites R. Felder, one of the BMG poskim. As you can see even though he is hesitant to issue a blanket heter he is confident that the ikkar hadin is that there is no problem using the same oven for meat and dairy.

    *pan

  20. Our grandmothers may have had only one oven and smaller kitchen space, but they were home all day and had the time and focus to be on top of what was happening in the kitchen, not to mention the yiras shomayim to ask a shayloh when needed.

    They had the ignorance to not know if a shayloh was needed, and who knows if their generation actually had more yiras shomayim than ours?

  21. B’mchilas kvod torascha, There are many halachic issues that seem to be unexplored here – including:
    1. Although the gemara paskens reicha lav milsa bdieved, the Rema (y”d 108) further qualifies that ruling that Reicha lav milsa only bmakom hefsed meruba, a psak that is echoed by the Shach and Pri Megadim.
    2. it is unclear that “our large ovens with ventilation” would be excluded from this issue as the pri megadim (sd 17) rules that one may only be lenient bmakom hefsed meruba if the oven is vented, unless it is “entirely open”.
    3. As the Rosh himself is mesupak, many poskim are choshesh for “reverse zaya” and therefore even if the steam hits hot walls it still may assur – see minchas yaakov 56, 26 and r’ akiva eiger Y”D 92, seif 8, and O.c. 451, mg”a 44. [although the abovementioned aruch hashulchan does not hold like this]
    4. although rav moshe ruled like the pri megadim and pischei teshuva by completely dry items, most of our food that we place in still create zaya as they are not true solids – ex. even a solid cake batter starts out in a liquid form – see Teshuvos v’hanhagos vol.1 ,430.
    5. the diyuk from the aruch hashulchan is not exact as he does not necessarily refer to our ovens, rather cases where zaya “goes out to the side in a completely open space”, not necessarily where it can circulate in an enclosed space.
    6. ovens, as opposed to other dishes, are considered to be dirty unless one is certain they are clean – see Taz end Y”D 95, and PMG there who rule like Tosafos.
    7. the vast majority of contemporary authorities are choshesh for zaya in ovens and are not too keen on allowing one to cook one right after the other without at least a proper cleaning and at least some sort of heating up to burn out potential mammashos and zaya.

    feel free to contact me on topic, as it seems that there is much unexplored territory here.

  22. Ybs –

    It’s a bit difficult to say that the vast majority of poskim rule lechumra when some of the most maistream Lakewood poskim rule lekula. Moreover, I would posit that many poskim who do rule lechumra do so as a matter of chumra and not ikkar hadin.

    As for our ovens not being open enough, it was R. Aharon’s and others’ opinion that the ventilation in contemporary ovens renders them completely open.

    Also btw most rishonim learn that the final halacha is that reicha lav milsa even lechatchila. See the BY.

  23. Fotheringay-Phipps

    ovens: “since the oven is “hetera bala”- this machloket would seem to not be relevant and all would agree that libun kal should be sufficient?”

    RMF’s position was not based on kibol’o kach polto, but on the notion that the coating of the ovens is cheres.

    There is an oral tradition (possibly told by R’ Tuvia Goldstein, although I could be remembering wrong) that RMF retracted his position later in life.

    Larry Lennhoff: “We use the self clean cycle to kasher the oven between milk and meat.”

    At least one appliance repair guy told my wife that self-cleaning too often ruins the oven.

    Dov: “He cites R. Felder, one of the BMG poskim. As you can see even though he is hesitant to issue a blanket heter he is confident that the ikkar hadin is that there is no problem using the same oven for meat and dairy.”

    FWIW, R’ Felder’s position is similar to what various commenters have said here – “open an oven and you won’t see any steam”.

  24. Larry Lennhoff

    FP: “At least one appliance repair guy told my wife that self-cleaning too often ruins the oven. ”

    I’ve heard the same thing, but I’ve been self cleaning my present oven approximately once every 2 weeks for 8 years and we haven’t had any problems yet.

  25. What about the situation where you have double oven, one on top of the other, so to speak, in one unit.
    It seems to me there might be an issue despite the fact that they are separate ovens when the two share a common ventilating outlet from behind?

    Thoughts?

  26. To Anonymous –
    I can’t answer up for whichever lakewood poskim you are referring to,
    yet, the opinions of the gedolei hador including Rav Moshe Feinstein (Ig”m Y”D 1, 40), The Minchas Yitzchak (vol. 5, 20:8), The Chelkas Yaakov (vol 2, 36), the Shevet halevi (kovetz mbais levi vol. 3, pg. 21), r Moshe Sternbuch (teshuvos vhanhagos vol 1 , 430) and R Bentzion Abba Shaul (ohr ltzion vol 3, pg 115 -116) in my opinion should not be treated lightly. – not to say that theres is not what to rely upon bdieved, [the maharsham vol 3 208,& yaavetz vol 1, 93 are maykel bdieved either way] but to be meykel lchatchila? even R’ Ovadia -(yabea omer vol. 5 yd 7) who is the most meikel on this topic that i have seen – concludes not to put one after the other if they are not both completely dry food items!
    don’t take my word for it – go through the teshuvos yourself!

    #2 i didnt make case in the rishonim – obviously its a machlokes (and even in the sugya). i simply pointed out that the rema,[ also shach and pri megadim] – who ashkenazi psak follows – does not hold that way and in this exact case rules that only bmakonm hefsed meruba ! i do not see how that came to be psak lmaaseh lchatchilah!

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