Question: Is there a prohibition of Bishul Akum if an akum heats up food in a microwave oven?

Short Answer: There is no prohibition of Bishul Akum when an akum reheats previously cooked food in a microwave. There is a dispute amongst the contemporary poskim whether there is a prohibition of Bishul Akum when an akum cooks uncooked food in a microwave; but many are lenient, especially in a b’dieved situation.


I. Reheating

As an initial matter, there is no “bishul achar bishul” by bishul akum. See, e.g., P’ri Chadash (Yoreh Dei’ah 113:7). Accordingly, it is clear that there is no prohibition of Bishul Akum where an akum heats up a frozen but cooked food in a microwave.

The entire discussion herein refers to foods that are not yet cooked and are being cooked for the first time in a microwave oven (such as a potato or oatmeal). If an akum places the foods in the microwave and presses the buttons of the microwave to cook these foods, is there a prohibition of Bishul Akum?

II. Smoked and Salted

The Tur (Yoreh Dei’ah 113:13) rules that there is only a prohibition of Bishul Akum where the akum cooks food by using “fire.” Even though salting and pickling are considered a type of cooking for other aspects of halachah, there is no Bishul Akum prohibition if an akum salts or pickles a dish.

The Beis Yosef (ibid) cites a few sources for the ruling of the Tur. First, the Rashba rules this way, as the Mishnah employs the language of “shlakos” (boiled vegetables) when referring to bishul akum, and shlakos is food cooked with fire. Indeed, the Gemara has an entire discussion explaining that water has no prohibition because it is not changed by the fire, implying that the entire prohibition is connected to cooking by fire.

Moreover, the Beis Yosef notes that the Gemara (Avodah Zarah 38a) rules that there is no bishul akum by salted fish. Additionally, the Yerushalmi rules that there is no bishul akum by smoked foods.

Based on this, the Shulchan Aruch (Yoreh Dei’ah 113:13) likewise rules that there is no bishul akum prohibition if an akum salts or smokes foods. The Rama adds that there is also no prohibition if the akum pickles a food, as bishul akum only applies where the akum uses fire to cook the food.

Accordingly, one would assume that there is no bishul akum if an akum cooks a food in the microwave, as the microwave does not use fire to cook, but instead heats and cooks food by exposing it to electromagnetic radiation.

III. Solar-Cooked

The Gemara (Shabbos 39a) rules that one who cooks by using the heat of the sun (i.e., solar cooking) has not violated the prohibition of cooking on Shabbos. Rashi and the Ran explain the reason for such leniency: because “ein derech bishul b’kach” – this is not the normal way to cook.

The Igros Moshe (Orach Chayim 3:52) extrapolates from this Rashi and Ran that alternate forms of cooking are prohibited on Shabbos, as long as they are normal methods of cooking. Rav Moshe suggests that a microwave is a normal method of cooking and thus would fall under the prohibition of cooking on Shabbos. Indeed, he suggests (in this 1971 t’shuvah) that microwave cooking will be more common when microwaves become more common.

However, because Rav Moshe is only talking about microwaves and the prohibition of cooking on Shabbos, it is unclear what Rav Moshe holds with respect to microwaves and bishul akum, as will be discussed further herein.

IV. Strict Opinions

The Sh’vus Yitzchak (Vol. 6, p. 60), cited in Kovetz Beis Yitzchak (Rav Almog Levi, Vol. 20, p. 67), rules stringently in the name of Rav Yosef Shalom Elyashiv. Indeed, the Sh’vus Yitzchak holds that even the Rashba, who required cooking by fire in order to violate Bishul Akum, would agree. Fire is simply a way of referring to normal cooking methods. Since cooking via microwave is a normal method of cooking nowadays, there is a prohibition of Bishul Akum.

The Sheivet HaLevi (8:185) likewise rules stringently that there is Bishul Akum by a microwave. Since both reasons for Bishul Akum – intermarriage and non-kosher food, see Article #1 – apply, as well, in microwave cooking, there is no reason why the prohibition should not apply. In fact, the Sheivet HaLevi is clear that the only exceptions to Bishul Akum are those listed in the Gemara and Rishonim: smoking, salting, and pickling. Microwave cooking, a normal way to cook nowadays, was never excluded. Rav Noach Isaac Oelbaum shlita (Minchas Chein 4:13), while agreeing that there is room to be lenient, cites the Sheivet HaLevi approvingly and rules that one should be strict l’chatchilah. See also Ohel Yaakov (p. 187).

The T’shuvos V’Hanhagos (5:249:2) also rules stringently, as microwave cooking is an accepted and normal practice nowadays.

Indeed, the Chelkas Binyamin (n. 320) understands that Rav Moshe Feinstein, by ruling that microwave cooking violates cooking on Shabbos, would similarly rule that there is a Bishul Akum prohibition by microwaves. However, the Chelkas Binyamin personally rules “tzarich iyun” whether microwave cooking violates Bishul Akum.

The sefer Reishis Darko (p. 63) cites the sefer Otzar Hilchos Bishulei Akum who cites the following poskim zt”l, who ruled stringently: Rav Shlomo Zalman Auerbach, Rav Y.Y. Fischer, Rav Ezriel Auerbach, and Rav Dovid Feinstein. [The sefer Reishis Darko, however, queries whether this question is even relevant, as many foods that are cooked in a microwave would not be served on a king’s table and are thus exempt from Bishul Akum, see Article #6].

V. Lenient Opinions

On the other hand, many poskim rule leniently on this issue. For example, the article in Kovetz Beis Yitzchak disagrees with the abovementioned Sh’vus Yitzchak. He argues that even nowadays, microwaves are not really used for first-time cooking of foods but merely to reheat frozen foods. As such, there is no bishul akum. And Rav Moshe Feinstein, who forbade cooking in microwaves on Shabbos, never discussed bishul akum and would not necessarily apply such a stringency for bishul akum.

The Riv’vos Efraim (8:511) similarly limits Rav Moshe’s stringency to cooking on Shabbos and concludes that there is likely no Bishul Akum prohibition on all non-fire cooking, including a microwave. However, the Riv’vos Ephraim does state that he personally refrains from eating foods cooked by an akum in a microwave.

The article in Kovetz Beis Yitzchak also cites Rav Asher Weiss shlita as ruling that there is no Bishul Akum through a microwave, as this is not fire, and anyway, this is not a normal way of cooking, even nowadays. Interestingly, the article also cites Rav C. P. Sheinberg, who suggested a leniency based on an understanding that microwave cooking is only g’rama – indirect cooking.

The L’horos Nasan (7:64) also rules leniently, as the Gemara in Shabbos (cited as the basis for Rav Moshe’s stringency by cooking on Shabbos) actually proves the opposite. We are not going to be stricter for bishul akum, a Rabbinic prohibition, than solar cooking, regardless of how “normal” this cooking is nowadays. See also Mishneh Halachos (19:105).

VI. Practically Speaking

The OU, in an article on its website, advises that “[s]ince microwave cooking is a new innovation, it is treated as unconventional, and bishul akum would not apply. Other contemporary poskim argue that, today, microwaves have become a standard mode of cooking, and therefore bishul akum is a concern. We therefore recommend that you consult your local rabbi or community kashrus agency.” See 

The Star-K rules that “[b]ishul akum does not apply to microwaved food. The rabbinical prohibition of Bishul Akum applies only to conventional cooking methods through fire (e.g., cooking, frying, roasting). Food prepared through microwaving is not included in the prohibition.” See 

My poskim, Rav Mordechai Willig shlita and Rav Hershel Schachter shlita are cited as being lenient, as well. See  and  


Next Week’s Topic: If an akum uses your pot to cook himself (kosher) food, must you kasher the pot?

Rabbi Ephraim Glatt, Esq. is Assistant to the Rabbi at the Young Israel of Kew Gardens Hills and a practicing litigation attorney. Questions? Comments? Email: This email address is being protected from spambots. You need JavaScript enabled to view it..