Rabbi Mendel Agranovich
Hello, dear readers!
Before we begin discussing the rules for reheating food on Shabbat, we must introduce and discuss a few more concepts. Specifically: when cooking begins and ends, at what temperature and at what stage.
Let us introduce the following concepts:
1) undercooked food;
2) food cooked on Shabbat in an amount smaller than a dried date;
3) food cooked to the stage of “the food of ben Derusai”;
4) partial participation in the cooking process;
5) speeding up the cooking process.
1. Undercooked food. Whether food is cooked or uncooked is measured by the time needed to bring it from a state in which it is unfit to eat to one in which it is fit for consumption.
This time is counted from the moment when the entire system (the water, the pot, the piece of meat or the raw vegetable) reaches the temperature at which “the hand recoils.”
A reasonable question arises: if someone simply places a pot of food on the fire and immediately removes it (or removes it before cooking is complete), what has that person violated—a Torah prohibition or a rabbinic enactment? In other words, has someone who cooks meat halfway violated Shabbat? After all, that meat is unfit to eat.
It is written in the Talmud (tractate Beitzah, 34a): “The one who brings the fire, the one who brings the firewood, the one who places the pot on the fire, the one who pours in the water, the one who adds the seasoning, the one who stirs while it is on the fire—all are obligated [to bring a sin offering—chatat—for inadvertently violating Shabbat].” Yet in another source we find: “Our Sages taught that all are exempt (from that same offering); only the last person is obligated to bring it.”
There is an apparent contradiction: who is obligated to bring an offering—everyone, or only one person? The contradiction is resolved simply: the first statement concerns a situation in which the fire was lit at the beginning, while the second concerns a situation in which it was lit at the end. Based on the Talmudic passages quoted above, someone who performs an intermediate step in preparing food does not always violate a Torah prohibition.
To better understand this passage, we need to know the following laws:
– anyone who violates Shabbat inadvertently (someone who did not intend to violate it knowingly, or did not know the full severity of the law) must bring an offering;
– the action must be significant in both qualitative and quantitative terms.
Quantitatively, our Sages received a tradition from Moshe Rabbeinu that the food must have a volume no smaller than a dried date and must be regarded as food.
Qualitatively, the food must be cooked halfway (according to some opinions, one-third of the way). This measure is commonly called “the food [the degree of doneness of food] of ben Derusai” (after the bandit ben Derusai, who ate food that was not fully cooked).
An important note. Why should the conditions under which some bandit ate, and his eating habits, serve as an important criterion in defining cooking? Answer: anyone who constantly faces extreme circumstances becomes accustomed to eating such food. But this is a criterion for the minimum doneness of food as perceived by a normal person, even one facing extreme circumstances, rather than a standard of behavior. Ben Derusai is merely an example, nothing more.
It is also important to note that this allows us to classify cooking, as a process of treating materials with heat, rather than only as a process of preparing food that depends on timing and housewives' customary practices.
Thus, food has a clear criterion for doneness —the material is considered raw until it has been cooked to the stage of “the food of ben Derusai,” and cooked after that stage. But even if the food had not reached the stage of “the food of ben Derusai” and was smaller than a dried date, Shabbat was still violated: according to some opinions, a Torah commandment was violated; according to others, a rabbinic prohibition was violated.
Conclusion. If each participant performed a qualitatively significant action that could produce the result (as in the example where the fire was lit at the beginning of cooking), then all committed a violation, since they were part of an overall process that already constituted cooking in the full sense. But if the fire was not burning and was brought only at the end, then those who did anything before the fire was lit violated the rabbinic prohibition against engaging on Shabbat in processes closely related to cooking, but did not violate the Torah prohibition.
Thus, we see that both the process (the fire is already burning) and the result (material equal in volume to a dried date must be cooked to the stage of “the food of ben Derusai”) matter in determining that the prohibition against cooking is being violated. As we have already said, anyone who cooks without meeting these criteria violates, at the very least, a rabbinic prohibition (this is evident from our Talmudic passage, which states that if the action is performed, the person is exempt from bringing an offering; we know that there is a rule in the Talmud that when it says “exempt,” it means exempt from punishment or an offering, but the action may not be performed in the first place).
There is another important question: cooking beyond the stage of “the food of ben Derusai.” In other words, if a dish is half-cooked and someone cooks it until it is fully done, what is the law in such a case: is a Torah law or a rabbinic enactment being violated? Or is such an action permitted?
The Mishnah Berurah's ruling on this subject directs us to another very interesting question: if someone cooks foods that are fit to eat, without an obvious cooking process, what is the law in that case? Baked apples can serve as an example. On the one hand, they can be eaten without any heat treatment, but on the other hand, the clear aim is to obtain a different flavor. And the result is evident: baked apples are a new dish, fundamentally different from the raw food. This was precisely the Chafetz Chaim's view, and he recorded it in his code, the Mishnah Berurah, based on the opinion of the great Rabbi Akiva Eiger, one of the most outstanding halachic authorities of recent generations. Cooking food from the stage of “the food of ben Derusai” to full doneness can likewise be understood, in our perception, as producing a significant flavor or a fundamentally new flavor, and is therefore also prohibited by the Torah. But since there are other opinions, the Mishnah Berurah rules as follows: one may not do this in the first place, since it is prohibited by the Torah, but if someone made a mistake and cooked it, everyone may eat it on Shabbat, including the person who made the mistake.
Another important question concerns speeding up cooking and improving its quality by stirring or moving the food closer to the fire. If the pot is on the fire, this is prohibited by the Torah, while the related rabbinic laws require a separate discussion.
And the final theoretical question: may someone place raw food somewhere it could cook if the original intention is only to bring it to room temperature, rather than to cook it? There is a clear rabbinic ruling on this: if the location is such that food left there could cook through, it may not be placed there even for a short time. If, however, there is no such possibility and it will never reach a temperature of 42-45 degrees Celsius, then it is permitted.
Overall conclusion. There are two different ways of viewing Shabbat prohibitions, and the cooking process in particular:
1. A process of treating materials. Based on our definition of “the food of ben Derusai,” we can say that cooking:
A) is an objective process of treating materials (this definition allows us to view cooking in the same way as, for example, the processing of hides);
B) has a clear boundary between the raw state and the cooked state—when the food is half-cooked, or one-third cooked (according to some Sages).
2. A process that depends on human perception. If someone cooks foods that are edible raw, that person also violates the prohibition against cooking. Baked apples or apple compote are examples.
Let us say a little about the temperature at which cooking begins, namely 45 degrees Celsius.
As we know, the Talmud has no Celsius or Fahrenheit scale. It has only the concepts of “the hand recoils” and “a baby's tummy is burned.” Why is this specifically the criterion? We venture to suggest that a burn indicates that the material is being cooked.
The rabbis of recent generations, particularly Rav Shlomo Zalman Auerbach, faced the question of how to express these concepts as a specific, measurable temperature, and where exactly the threshold lies. This is one of the clearest examples of how Rav Shlomo Zalman's precise, clear thinking, vast Torah knowledge, and remarkable practicality enabled him to clarify this subject for the entire Jewish people.
So Rav Shlomo Zalman used:
1. The proof presented by the author of Darchei Teshuvah, stating that freshly drawn milk (immediately after milking) has a temperature of 40 degrees Celsius and is considered “cold,” as written in Halachot Gedolot.
2. A duck's temperature at the time of its shechitah cannot be below 45 degrees (as established experimentally). It is also written about it in the Talmud (tractate Chullin, 8b) that even the neck and blood of a sick (treifah) duck during shechitah are considered “cold” (this matters in establishing that the knife remains kosher after shechitah). Even according to the Sages who hold that the site of shechitah “boils,” its temperature does not reach the point at which “the hand recoils” (Ritva).
It follows that food is considered cold up to 45 degrees.
3. The upper limit is based on Rav Moshe Feinstein's opinion. It is 80 degrees Celsius. In other words, cooking begins at a temperature of 45 degrees Celsius.
Three important practical points:
1. Wet clothing may not be dried if the water could reach a temperature of 45 degrees Celsius, whether someone is wearing it or it is hanging up;
2. Challah from the freezer may not be warmed if there is ice on it that could heat up to 45 degrees Celsius (even if it later evaporates—we still want that outcome, and it is forbidden);
3. Challah may be heated on top of a kettle if it has first absorbed liquid outside the freezer (note that the ice must not be removed from it, to avoid violating the prohibition of sorting).