by Rabbi Wayne Allen
Disclaimer: The opinions expressed here are that of the writer and do not necessarily represent the views of the Union for Traditional Judaism, unless otherwise indicated.
The following responsum is reprinted from Tomeikh KaHalakhah volume 2. Tomeikh KaHalakhah is UTJ’s series of volumes of responsa (teshuvot) promulgated by the Union For Traditional Judaism’s Panel of Halakhic Inquiry.
The text below is the result of OCR. Although it has already been reviewed, if you identify any errors, kindly email office@utj.org. A scan of the original teshuvah is available here.
With the popularization of the microwave oven, snack bars and kitchenettes in schools and businesses have made them available for public use. Anyone can buy a sandwich or soup in a container and heat his or her lunch in a matter of minutes. Yet those who are concerned about kashrut must take a more cautious approach in using these ovens.
The microwave oven is not like other modes of cooking mentioned by the classical sources. The microwaves excite the food molecules causing them to move so rapidly as to produce heat. There is no flame and there is no external heat source; only the heat generated inside the food itself. According to Halakhah, heat from a source other than fire does not suffice to cause a transfer of the essence of the forbidden food stuff that may be on the walls of the oven or absorbed in the walls of the oven to the permitted foodstuff (See Maimonides, Laws of F orbidden Foods 9:6; Shulhan Arukh, Yoreh De’ ah 87:6; also Y. Levi, “Esh bailalakhah”, in Yad Re’ em, Jerusalem, 1974). With microwaves there is, therefore, no cooking in the halakhic sense. Thus, the rules prohibiting the use of Gentile cooking utensils, prohibiting contact with non-kosher elements during cooking, and requiring purg- ing before use of the same, do not apply (See Avodah Zarah 75b). There simply is no absorption or transfer by heat in a microwave oven.
Since there is no cooking per se in a microwave oven, it is placed in a category of far greater leniency than a regular oven in which, under certain circumstances, it is even permitted to cook forbidden and permitted foods or even dairy and meat foods provided that they do not mix with one another (S hulhan Arukh, Yore h De’ ah 108:1).
However, foods placed directly in a microwave oven can come in contact with actual forbidden foods or dairy and/or meat particles that have adhered to the interior. Therefore, prior to heating a sandwich in a microwave oven, the observant user must make sure that the sandwich is double sealed in plastic wrap to insulate the kosher food from contact with other possible forbidden foodstuffs. Similarly, other foods sealed in an appropriate container can also be cooked or heated in the microwave. Kosher foods prepared in this way have been served to and eaten by many pious Jews who travel aboard airplanes without any objection. (See also Hadarom, vol. 15, Nisan 5722).
Rabbi Wayne Allen for the Panel of Halakhic Inquiry.
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Born and raised in New York City and currently a resident of Toronto, Rabbi Wayne Allen has blended a career of service to the Jewish community as an ordained rabbi with his academic pursuits. Rabbi Allen is recognized as an expert both in Jewish law and in 18th century British moral philosophy. The books he has written and those he has edited are distinguished by the inclusion of philosophical analysis and historical context, adding an extra dimension to the more traditional forms of responding to questions on Jewish practice. He is a panelist for Jewish Values On-line, an Internet site devoted to providing authoritative answers to questions on Jewish life.
Rabbi Allen has traveled extensively and has led groups to Europe and Israel, lecturing beforehand on the history of the communities to be visited. He has served as a faculty member at the American Jewish University where he taught Jewish law, at California State University Long Beach where he taught the History of Modern Jewish Thought and Zionism, and at the University of Waterloo where he taught Theology After the Holocaust. He has also been invited as a guest lecturer at York University in Toronto and at the Pardes Institute in Jerusalem.
Rabbi Allen has served as a scholar-in-residence at synagogues in St. Louis and Ottawa and currently teaches at the Community Hebrew Academy of Toronto where he serves as chairman of the Rabbinics Department.
Samples of Rabbi Allen’s teaching are accessible on his website, www.rabbiwayneallen.ca.
Rabbi Allen's published books, available from the UTJ Bookstore are: