Article: Kashrus Q: What is the upshot of steam?
Halachah considers Zeiah (steam or vapor) generated by high temperatures to fall under the same category as the food that emits it, whether what’s cooking is solid or liquid: A Fleishig (meat) dish produces Fleishig steam, a Milchig (dairy) dish produces Milchig steam, and one that has become Treif (non-kosher) will produce Treif steam. The steam that rises from an uncovered dish affects whatever is placed above it, for hot steam transfers taste through B’liah (absorption).
How Hot is Hot?
Only steam that is Yad Soledes Bo transfers its status through B’liah. Therefore, a Pareve (neutral, i.e., not meat or dairy) food or pot that rests above an uncovered (or partially covered) Fleishig pot emitting steam that is Yad Soledes Bo will likewise become Fleishig; if a Milchig pot is steaming below a Fleishig pot (or vice versa) the food in the pot above becomes Basar B’Chalav (forbidden mixture of meat with milk), and therefore Treif (non-kosher). If either the top or bottom pot was covered or the food was wrapped, it may be eaten. But we are generally careful not to place food to be heated in this manner L’Chatchillah (initially).
If the steam in the pot below is not Yad Soledes Bo, it may still potentially affect what is on top of it: If the pot above is Yad Soledes Bo, the cooler steam from below will be absorbed. However, if neither the steam from below nor what rests above it are Yad Soledes Bo there is no absorption, and the food (or utensils) need only be rinsed.
Not All Good in the Hood
In general, we should avoid cooking Milchigs and Fleishigs in close proximity, as spills and condensation can transmit steam from one pot to the other. However, even if the pots touch each other, if they remain dry on the outside, they are both kosher B’dieved (ex post facto).*
A range hood that covers an area where both Milchigs and Fleishigs were cooked simultaneously or in succession (within twenty-four hours of one another) absorbs the steam from each pot and may render the hood treif. The hot treif steam is absorbed in turn by the pots below, making them treif, as well. If it is determined that the steam rising from both pots cooled to the point that it was not Yad Soledes Bo when it reached the hood, the hood is unaffected.
(It’s advisable to consult a Rav before assuming that food or utensils have become treif, as in many matters of kashrus. Disposing of suspect “Treifed up” food or utensils without confirmation may violate the Issur (prohibition) of Bal Tashchis (wastefulness)).
*For more information on dairy and meat pots—Shtei Kedeiros—in proximity, see Halachic Article #352.
On the subject of stove grates and Shtei Kedeiros, see Halachah #425.
From Halacha2Go Archives
#706
