The Laws of Nitzok and Steam

The Law of Steam Rising from a Cooked Dish

It is common that while cooking, one pours oil from a bottle or spices from a jar into a pot of food standing on the fire. Usually, because the food is boiling, steam rises from it. One must therefore discuss a case in which the pot contains prohibited food: do the oil or spices become prohibited because of the steam?

There are two issues to discuss here:

1. — the law of nitzok.

2. — the law of ze’ah, steam.

The Rema writes (Yoreh De’ah, siman 105, se’if 3): “It is forbidden to pour from a vessel containing kosher fat into a burning lamp that contains forbidden fat or chelev; but after the fact, there is no concern.”

The Taz there, se’if katan 6, explains the reason: “because the lower item prevails and connects it through nitzok.” The Shach there (se’if katan 11) writes that it is because of the vapor rising from the lamp. The Pri Megadim (Mishbetzot Zahav, siman 105, se’if katan 6) explains: “It is forbidden initially because of nitzok, meaning that through nitzok the vapor rises upward, etc.; the explanation of the Taz and the Shach is one and the same,” see there. It is thus clear from the Rema that one should not pour from a vessel containing kosher food into a vessel containing hot forbidden food, because of the law of nitzok.

This law applies only initially. However, after the fact, if one did so, nitzok does not prohibit. The Gra explains the reason: only regarding wine used for idolatrous libation and ritual impurity does nitzok prohibit after the fact, since the matter depends merely on contact; but regarding prohibition and permission this is not so, since the taste of the prohibition does not pass through nitzok.

It is clear from the Rema that when pouring cold kosher fat into a vessel containing hot forbidden fat, it does not become prohibited because of nitzok.

However, we must explain why the kosher fat does not become prohibited because of the rising steam. For the Responsa of the Rosh (klal 20, siman 26) states: “From all of these sources we learn that steam emerging from something is considered like that thing itself. It follows that the steam of a dairy pot is like milk, and it is like a drop of milk that fell on the outside of a pot, which prohibits the pot.”

From his words — and so it is ruled in the Shulchan Aruch (Yoreh De’ah, siman 92, se’if 8) — it is clear that steam (ze’ah) of food is considered like the food itself. If so, the words of the Rema require analysis: why, after the fact, is the upper food not prohibited because of nitzok, and why should it not be prohibited because of the rising steam?

One may answer that in a lamp containing chelev there is only a small amount of vapor, unlike a boiling dish, from which a large quantity of steam rises.

One may also say that the case is one in which the heat of the steam is not yad soledet bo — hot enough that a hand recoils from it — and it is explained (in siman 92, se’if 8) that steam prohibits only if it is hot to the degree of yad soledet bo.

Another possible answer is that the Rema is speaking of a case in which one pours from the side into the pot; steam prohibits only when it rises upward, but when it spreads to the sides it does not prohibit, as explained in the new Responsa of the Bach (part 2, siman 24) and in the Responsa of Maharsham (part 4, simanim 85 and 119).

We have learned from the words of the Rema that initially one should not pour from a bottle of oil or a jar of spices into a pot in which prohibited food is cooking, because of the law of nitzok. But after the fact, if one poured, it does not become prohibited; and the steam does not prohibit if it is not hot to the degree of yad soledet bo, such as when one pours from high above or from the side.

Separate Oil Bottles and Spices for Meat and Dairy

According to the above words of the Rema, one must discuss whether a home requires two bottles of oil — one for dairy and one for meat — and likewise whether separate spice jars must be designated for meat and dairy. After all, the Rema writes that initially one should not pour from them into a prohibited item; if so, the same might apply to meat and dairy, both because of nitzok and because of the steam. Regarding nitzok, however, one can distinguish: the Rema’s words prohibiting this initially because of nitzok apply only when one pours into prohibited food or drink; but if one pours into something permitted, it would seem that we do not find a law of nitzok in such a case (though see siman 95, the Taz and Pri Megadim there).

Nevertheless, the matter still requires discussion with regard to steam: when one pours from an oil bottle or from spice containers into a boiling pot of meat or milk, and steam rises from it, do the oil or spices become meaty or dairy?

Indeed, as explained above, steam does not prohibit if it is not hot to the degree of yad soledet bo, such as when one pours from high above or when one pours from the side.

We have therefore learned that, according to the basic law, we have not found that two bottles of oil — one for meat and one for dairy — are required when pouring directly from them into the pot; and the same applies to two spice containers. This is because generally one pours from the side, or even if one pours above the pot, the steam does not have heat of the degree of yad soledet bo.

A Separate Kettle for Meat and Dairy

Above, it was explained from the words of the Rema (Yoreh De’ah, siman 105, se’if 3) that because of the law of nitzok, one should not pour cold kosher food into hot non-kosher food. The source of this law is a Mishnah in Machshirin, chapter 5, mishnah 10: one who pours cold ritually pure liquid into hot ritually impure liquid — the upper liquid becomes impure. The Sages were stringent initially to apply this law also to prohibitions; however, after the fact it prohibits only with respect to wine used for idolatrous libation and ritual impurity, as stated above.

But there is room for doubt in the reverse case: if the upper liquid is hot and the lower food is cold. This is common when one pours from a kettle into a cup of milk or over frozen meat to thaw it: does the kettle become dairy or meaty?

It is explained in the Shulchan Aruch HaRav (siman 451, se’if 59), and likewise in Chok Yaakov (siman 451, se’if katan 57), that even when pouring hot into cold, one should initially be stringent regarding the law of nitzok; but this is not the place to elaborate.

According to this, it would seemingly be forbidden initially to pour directly from a kettle into a cup of milk or over frozen meat.

However, as stated, one may argue that wherever we find the law of nitzok, it is only with regard to a prohibited item and not with regard to a permitted item. Therefore, it is permissible to pour from a hot kettle into a cup of milk that is not hot, or over frozen meat. As for the steam, there is no concern, since the kettle is boiling, as explained below.

Pouring from a Hot Kettle into a Pot of Cholent Standing on the Fire

Above, it was explained from the words of the Rema (Yoreh De’ah, siman 105, se’if 3) that because of the law of nitzok, one should not pour cold kosher food into hot non-kosher food.

One must consider a case in which both the upper and the lower items are hot: is there a law of nitzok in such a case?

The Chochmat Adam and the Yad Yehudah disagree about this. In Chochmat Adam (klal 59, se’if 5), he rules that only from cold into hot should one not pour initially; but from hot into hot it is permitted to pour initially. According to his words, it would be permitted initially to pour hot water from a kettle into a boiling meat pot, and the kettle would not become meaty. However, the Yad Yehudah (siman 105, ot 31) maintains that even from hot into hot one should be careful initially, and the Pri Megadim (siman 105, Mishbetzot Zahav, se’if katan 6) is uncertain about this.

In practice, we rule like the Chochmat Adam that from hot into hot it is permitted to pour initially even into a prohibited item, and all the more so when pouring into a permitted item, where there is room to argue that the law of nitzok does not apply at all; and even according to those who prohibit, this case is permitted.

However, clarification is needed: why do the vapors rising from the pot not prohibit the kettle by the law of ze’ah, steam (Yoreh De’ah, siman 92, se’if 8)?

One cannot say that we are speaking of steam that is not yad soledet bo, for the Terumat HaDeshen (part 2, siman 103), cited by the Pri Megadim and Rabbi Akiva Eiger (there), writes that if the vessel into which the steam is absorbed is boiling, it becomes prohibited even if the steam itself is not hot to the degree of yad soledet bo. However, the Rosh wrote (Responsa of the Rosh, klal 20, siman 26): “Indeed, one must know whether a boiling pot absorbs steam, for perhaps the heat of its boiling prevents it from absorbing the steam.” Here too, since the kettle is boiling, it does not absorb the steam rising toward it from the pot.

Indeed, in the above-cited Terumat HaDeshen the opposite is implied: if the vessel receiving the steam is boiling, it becomes prohibited even if the steam is not hot to the degree of yad soledet bo; and this requires further analysis.

In practice, it appears that the words of the Rosh should be followed, as explained by the Maharsham (Responsa, part 4, siman 85), who writes: “But if the upper pot was boiling, one may combine the reasoning of the Responsa of the Rosh, cited in the gloss of Maharlach on the Tur Yoreh De’ah, see there; especially since it has already been written in the new Responsa of the Bach, siman 24, that the entire prohibition of steam is only a stringency, and in every case of doubt one should be lenient, etc.” See further there. See also Responsa Mishkenot Yaakov, Yoreh De’ah, siman 34; Yad Yehudah, long commentary, siman 92, ot 55; and Magen Avraham 451, se’if katan 54.

The Novel Ruling of the Bach Regarding Steam that Rises Gently and Does Not Prohibit

It is explained in the new Responsa of the Bach (part 2, siman 24) that there was room to say that everything stated in the Responsa of the Rosh, klal 20, and ruled in Yoreh De’ah, siman 92, se’if 8 — that steam prohibits — applies only when the steam arrives with strong pressure, and in a narrow, confined place where the steam cannot spread to the sides.

But in an ordinary case, where the steam rises gently and has room to spread to the sides, it does not prohibit.

However, the Bach writes there that although this is how the halachah appeared to him, nevertheless, from Terumat HaDeshen, part 2, siman 103, cited in the above Rema in Yoreh De’ah, it implies that even where the steam spreads to the sides, it prohibits. Therefore he wrote that if it is certain that the steam is hot to the degree of yad soledet bo, one should be stringent. But if there is doubt whether it is yad soledet bo, it is permitted.

However, everything we have said — that steam prohibits even when it rises gently — applies only with respect to food located above the steam. But if it is to the side, even if the steam reaches it, it does not become prohibited, as explained in the Responsa of Maharsham (part 4, siman 119, and he inferred this from the words of the above Bach). The Maharsham also wrote there in siman 85: “Especially since it has already been written in the new Responsa of the Bach that the entire prohibition of steam is only a stringency, and in every case of doubt one should be lenient; for this reason, if the steam comes from the side, it should be permitted, see there.”