Shiur #09: X) Bishul Achar Bishul
LAWS OF SHABBAT: COOKING
By Rav Yosef Zvi Rimon
X) Bishul Achar Bishul
May one put cold soup on a hot plate?
Is one allowed to put soup that has started to cool on a hot plate?
May one heat up a food with its sauce on Shabbat?
Is it possible to prepare tea in a way that is permissible according to all views?
Until this point, we have dealt with uncooked foods. We have seen that it is forbidden to put these items in a keli rishon (primary vessel) even after it has been removed from the fire. We have seen that generally we are stringent and avoid putting them even in a keli sheini (secondary vessel), and there are those who are stringent even about a keli shelishi (tertiary vessel), particularly when it comes to food items that are easily cookable. Is the law different for cooked foods? Is it forbidden to cook a food that has been previously cooked?
The mishna (145b) rules:
Whatever was put into hot water before Shabbat may be steeped in hot water on Shabbat.
Solid Foods There is no bishul achar bishul
Thus, any cooked item (was put into hot water) may be put in hot water on Shabbat; from here we see that the prohibition of bishul does not apply to previously cooked items. Similarly, there is another mishna (36b) that states that a pot that has been taken off the fire may be returned under certain conditions since the food has already been cooked, bishul no longer applies. This rule is known as ein bishul achar bishul.
According to this, once an item is fully cooked, one may even put it in a keli rishon. However, as we shall see in a future shiur, there is a rabbinical prohibition to put cooked items in a keli rishon while it is on the fire, so that this lenient rule applies only to a keli rishon that is off the fire, or cases in which the Sages do not forbid (see loc. cit.), such as putting the item on top of the pot and the like.
Rashi, Rabbeinu Yona: Yesh Bishul achar Bishul Be-lach
However, a number of Rishonim limit ein bishul achar bishul, and they argue that one should distinguish between liquids and solids. As we shall see in a future shiur, there is a rabbinical prohibition to insulate foods (hatmana) on Shabbat. The Gemara (34a) states the rationale:
Why was it said that one must not insulate after nightfall even with a substance that does not add heat? For fear lest he make it boil.
Rashi (ad loc.) explains:
It is a decree lest he find that it is cold when he comes to insulate and he will heat it up first, and he will end up cooking on Shabbat.
In other words, before merely insulating it he will come to heat up on the fire (so that it will be fully hot when he insulates it) and he will violate the prohibition of bishul. How is this possible if we are obviously talking about a cooked food, and we should apply the rule of ein bishul achar bishul! The Rosh (3:11) deduces that Rashis view is yesh bishul achar bishul (there is a prohibition to cook even a previously cooked food item) when it comes to a liquid that has cooled off:
Rashi says that it is a decree lest he heat up a pot that has cooled down This teaches us that [the prohibition of] cooking is applicable even to an item that has been cooked and cooled, since there is a liquid in it. That which we say, Whatever was put into hot water before Shabbat may be steeped in hot water on Shabbat, refers to a solid, like a chicken
There are Rishonim who write explicitly that yesh bishul achar bishul for a liquid. This is what Rabbeinu Yona writes (Bava Batra 19a, s.v. Tenan hatam):
It is a great obstacle for some of the people: they insulate the urn of hot water to put it in the pot on Shabbat while the food is able to be cooked further, and sometimes one is yad soledet bo (scalding) and the other is not [and one cooks the other], and it turns out that they cook on Shabbat.
The Ran (22a, Rif, s.v. Ve-harav Rabbeinu Yona) cites the words of Rabbeinu Yona and challenges them:
I do not know where he gets this from, because Whatever was put into hot water before Shabbat may be steeped in hot water on Shabbat even though it is cold. What is the basis of distinguishing between boiled water and any cooked item? This requires investigation and analysis.
To the Ran, it is clear that ein bishul achar bishul applies to liquids as well: the simple meaning of the mishna is that is does not differentiate between different types of food. However, Rabbeinu Yona apparently believes that the mishna is speaking only of solids, but concerning liquids, yesh bishul achar bishul.
The Nimukei Yosef (Bava Batra 10a, Rif) confirms the view of Rabbeinu Yona, that yesh bishul achar bishul for liquids, and Rabbeinu Yerucham (column 12, part 3, p. 69a) writes this as well.
Other Rishonim There is Never Bishul achar Bishul
In fact, almost all of the other Rishonim do not address this, implying that ein bishul achar bishul is an absolute, ironclad rule, and one may heat even cold soup. This is the view of the Rambam, Ramban, Rashba, Remakh, Ran, Maggid Mishneh, and more.
The Shulchan Arukh rules (318:4):
[The prohibition of] cooking applies to a fully-cooked food if it cools But this is only so [that we apply the prohibition of] bishul achar bishul to a food that has soup in it. However, that which has been cooked and is solid may be steeped in hot water on Shabbat.
The Shulchan Arukh rules following the Roshs explanation of Rashi (against the Rambam and most Rishonim), that only concerning a solid do we say that ein bishul achar bishul, even if it is cold, but bishul does apply to a cooled liquid.
Below we will analyze the boundaries of the law and its practical ramifications. However, before we do this, we must analyze the reasoning: why is a solid considered cooked even if it cools, while a liquid loses its cooked status once it cools?
Liquids of the Type Not Eaten Cold
We may explain that the essence of bishul is to create a food by the application of heat, and there is a distinction between dry and fluid items concerning their status as food after they cool. Dry food, once it has been prepared by bishul, continues to be ready to eat even after it cools; almost every dry food can be eaten cold. On the other hand, if a liquid cools, it loses an essential element. Most people will eat cold chicken, but not cold soup. Naturally, a dry food retains its cooked status, while a fluid that is boiled and cooled is considered to have lost the nature of its bishul; it is now uncooked once again, and its heating is considered cooking.
The problem with this is that sometimes the reality is different: there are fluid things that are eaten cold, such as fruit soup or tomato soup; on the other hand, there might be solid things that are not eaten cold (e.g., congealed gravy; as we shall see in a future shiur, it becomes clear that it is considered solid). Nevertheless, we have not found that Rishonim and halakhic authorities argue that these foods should have a different status (or that the Sages decreed that we do not differentiate).
Liquid that has Cooled is Chemically Similar to its Original State
Still, we may explain the distinction between solids and liquids differently. It may be that the definition of bishul is changing a substance by way of heat. For solids, the essential chemical change that is accomplished through the cooking process remains after the food cools, and therefore there is no prohibition to come back and cook it. In fluids, on the other hand, the central chemical change is that the molecules move further apart, and from this point of view, when the fluids cool down they return to their original status, and therefore it is prohibited to reheat them. When the fluid is mixed with more dense items, such as in soup, the cooking process creates new links between the fluid and the dense items, and these links continue to exist after the food cools down. However, it is still possible to explain that since an element of the chemical change returns to its original state (distancing the molecules) there is a prohibition to cause this change to happen anew.
According to this definition, the prohibition consists of turning raw food into cooked food (and this is the view of the certain sage cited by the Shevitat Ha-Shabbat, Mevashel, Beer Rechovot, 75), and a cooled fluid is considered raw because its chemical composition is close to what it had been originally (cf. Chazon Ish 50:9, s.v. Ve-yesh).
When Re-heating a Liquid, the Change from Cooking Is Not Noticeable
With a slightly different formulation, one may explain that we do not investigate whether the central chemical change remains as it is, but whether the change done by bishul is noticeable and evident. Generally, when it comes to a solid, this change is noticeable even when the dish cools, while in a cooled liquid, the change is less noticeable, and therefore once it has cooled it is no longer considered cooked (Tehilla Le-David 318:33).
What is considered to be cold?
Thus, a cooled liquid is no longer considered cooked. At what temperature is this true? The Shulchan Arukh does not give an exact temperature (318:4):
[The prohibition of] cooking applies to a fully-cooked food if it cools.
Shulchan Arukh: Less than Yad Soledet Bo is Considered Cold
It is clear from other places that he is referring to the temperature of yad soledet bo. This is what arises from he writes in the Beit Yosef (318, s.v. Afillu),  and this is implied by what he writes elsewhere in the Shulchan Arukh (318:6): A vessel containing a food item that is yad soledet bo may be put on top of an insulated pot on Shabbat In other words, the temperature must still be at least yad soledet bo for the prohibition of bishul not to apply to this act.
This is also what many of the Acharonim write: anything that is no longer yad soledet bo is considered col. For example, the Mishna Berura writes (318:24): 
If it cools i.e., it is not yad soledet bo, even though it may still be somewhat warm. But if it is yad soledet bo, even though it has cooled from its seething temperature, cooking is not applicable to it anymore, because this is considered to still be in the category of seething, and ein bishul achar bishul This is the view of the Shulchan Arukh.
This approach is clear and logical. In a previous shiur we saw that one who takes an uncooked fluid and heats it up until the level of yad soledet bo violates the biblical prohibition of bishul. It makes sense, if so, that if we say that a cold fluid has lost its cooked status, it is referring to the fact that it has fallen below the level of yad soledet bo.
However, the Rema (318:15) surprises us with a lenient view:
There are those who are lenient, saying that this is permissible for anything not put on the fire or stove directly, but only close to it, even if it has cooled. People are lenient about this if it has not cooled fully, as I have written above, ch. 253.
In other words, as long as it has not cooled completely there is no prohibition of bishul (as long as one avoids the problems of mechzi ke-mevashel (the appearance of bishul) by not putting the food directly on the fire). This ruling requires explanation: as we have seen, the ruling of the Shulchan Arukh, that a liquid retains its cooked status as long as it is yad soledet bo, is quite acceptable, because yad soledet bo is the measure for defining a liquid as cooked. However, the qualification of if it has not cooled fully is a new measure [or way to determine if an action violates the prohibition of bishul], and what leads the Rema to adopt this new approach?
We may explain the Remas view in a number of ways. We will analyze two of them.
1. The Eglei Tal (Ofeh, 14; 55:5) understands that the Rema essentially adopts the stringent view of the Rishonim: a liquid that cools loses its status as cooked and there is thus a biblical prohibition of bishul involved.  However, as long as the food has not fully cooled, it does not lose its cooked status:
When it comes to the biblical prohibition, we follow the view of the stringent authorities, but when the food has not cooled fully and some people will still eat it due to its warmness, we need not be concerned about the biblical prohibition, as it is no worse than a minimally-cooked solid (maakhal ben Derusai, see the first shiur in this series), that though it has not been fully cooked, there is no biblical prohibition of cooking anymore.
In his view, a cooked liquid that has not fully cooled has the same status as a solid food cooked to the level of maakhal ben Derusai; if one cooks it further, one does not violate a biblical prohibition.
Difference between Initial Cooking and Cooling Off
However, we challenged this understanding above: how can it be that a liquid that merely has some warmth is considered cooked, when we have seen that one does not violate the prohibition of bishul for a liquid unless it is raised to the temperature of yad soledet bo! The Eglei Tal answers (Ofeh, 14, in the emended section) that one should distinguish between the criterion for creating the status of bishul and the criterion for its removal: in order to define a cold liquid as cooked it needs to reach the level of yad soledet bo; however after the liquid reaches this level and has been defined as cooked, its status cannot be nullified until it cools fully (being merely a degree below yad soledet bo is not enough).
2. The Chazon Ish (37:13 and 31) takes the opposite view. According to him, the Rema is following the view of most Rishonim that the rule of ein bishul achar bishul applies even to a cooled liquid:
The Rema writes that we are lenient, following the view of the Rashba and the Ran: even for a cooled liquid, ein bishul achar bishul.
If so, why does he demand that the food needs to be a bit hot? The Chazon Ish responds:
To prevent one from being lenient about raw ones, our custom is not to be lenient about items that have cooled to an extent that their warmth is not [easily] discernible.
A Modicum of Warmth
In other words, by the letter of the law, it is permissible to heat even a cooled liquid, but there is a concern that a person may warm a totally uncooked item, and therefore we require that the food must remain somewhat warm from the previous cooking; thus, it will be recognizable that this is a cooked item, and people will not learn from it to be lenient about heating uncooked foods. On the other hand, a cooked solid may be warmed even if it has totally cooled, since no one could err and miss the fact that it has been cooked.
In any case, even those who follow the Rema would not put a fully cooled liquid on a plata (hot plate), but rather only a cooked liquid that has not fully cooled. If one were to put a fully cooled liquid dish on a plata, then according to the explanation of the Eglei Tal (and similarly according to the Shulchan Arukh), this involves a biblical prohibition, while according to the explanation of the Chazon Ish in the Rema, this would involve a rabbinical prohibition only. This distinction may be relevant in cases of doubt, and we will discuss this in the future.
May a Non-Jew Heat Soup?
An additional ramification of this argument is whether a non-Jew may reheat soup on Shabbat. If the prohibition is biblical, one may not be lenient about it. However, if it is a rabbinical prohibition, one may be lenient for the sake of the Shabbat meal, if there is no other way to heat the soup. The Mishna Berura rules stringently (259:26; Beiur Halakha, 253:5, s.v. Lehachem, end), but the Chazon Ish (37:21) and the Chayei Adam (Nishmat Adam 20:10) are lenient.
If Sefardim take soup off the hot plate and want to return it, they must be careful that it not go below the temperature of yad soledet bo (there are also other laws of hachzara, returning items to a heat source, as we shall see in a future shiur). Ashkenazim, on the other hand, may return the soup even if it has fallen below this temperature, as long as it has not cooled fully. (If it has cooled fully, it is certainly forbidden, but Acharonim argue the correct way to understand the view of Rema, whether the prohibition is biblical or rabbinical.)
Defining Fully Cooled
The Rema does not define the term fully cooled, and instead just refers us to ch. 253. There (5) he writes:
One may not tell a non-Jew to heat up a pot that has cooled, and if one does so, one is forbidden to eat it, even when it is [again] cold. However, if it has not fully cooled, and it is still fit to eat, and a non-Jew heats it, one may eat it.
Shulchan Arukh Ha-Rav
The Rema mentions and it is still fit to eat. In light of this, the Shulchan Arukh Ha-Rav writes (318:9) that the definition of not fully cooled is still warm enough to eat. However, there is some reason to doubt this, because the Rema is dealing with benefit from a non-Jews act, and it may be that a high temperature is required, so that a Jew will not have material benefit from the non-Jews actions.
According to the Chazon Ishs understanding of the view of the Rema, that the need for the food to be not fully cooled is to prevent one from erring and cooking something totally uncooked, it makes sense that the definition is that its warmth is still noticeable (even if it is not warm enough to eat at this temperature). This is what the Chazon Ish himself writes (37:13, s.v. Ve-katav).
Apparently, one may challenge the view that believes that one must be able to eat it, because one may eat cold soup as well. Rav Feinstein explains (OC, part IV, 74, bishul, 2) that the definition is that the food must be fit to eat for those want to eat hot food. Rav S.Z. Auerbach (cited in Maor Ha-Shabbat, Vol. II, p. 36) adds that we define not fully cooled here by the way most people eat the food; in other words, we require sufficient heat that most people who are interested in eating the food specifically when it is hot would still be willing to eat it.
Cooled, Then Heated
If a cooked liquid that has fully cooled is heated somewhat afterwards (e.g., pouring on it from a keli sheini), may one continue to heat it? Apparently, one should allow this, since heating a cooked liquid that is somewhat warm is allowed. However, according to both of the above-mentioned explanations, it makes sense that one would not allow this. According to the Eglei Tal, it is clear that one should not allow it, because at the time the liquid cools, the former cooking is annulled, and heating it now will not help at all. According to the Chazon Ish, it makes senses that one should not be lenient about this, because the warmth is supposed to be a sign that the food has already been cooked, while after it cools, there is no significance to the initial heating, and there is no sign of the previous bishul.
The Eglei Tal, in his responsa (Avnei Nezer, OC 129:6), is asked about people who do so, and he concedes that the questioner is correct to condemn this practice (in accordance with his previously-expressed view). This is what Rabbi Akiva Eger writes (addressing Magen Avraham, 253:41). This is also the ruling of the Chazon Ish (37:13, end).
Translated by Rav Yoseif Bloch
 The Tur (ad loc.) also writes: [The prohibition of] cooking applies if it has already cooled down, but not while it is still seething. If so, the opposite of cooled is seething, and cooled does not refer to something that is actually cold. (Indeed, they may be simply using Rashis language, as cited above.)
 This is based on the assumption that the requirement that the pot be hot is because of bishul. We will see in a later shiur that the Magen Avraham (253:36) holds that there is a requirement that the pot be hot because of issues of hachzara, returning foods to the fire, but the Beiur Halakha (ad loc. 5, s.v. U-vilvad she-lo nitztanen) disputes this.
 This is how the other Acharonim rule, including the Minchat Kohen (II, 2), Magen Avraham (253:19), Eliya Rabba (253:19), Chayei Adam (20:8) and Kaf Ha-chayim (318:53).
 However, in the Chiddushim Ha-myuchasim La-Ran (40b, s.v. Shemen) we find an approach similar to that of the Rema: Now, we have something to say to allow putting hot water into hot food on Shabbat even though it may not be so hot anymore, as long as it is not yet cold, there is no issue of cooking This means that as long as a food has not fully cooled, there is no prohibition of bishul. It may be that this is the Remas source, but the idea is still not fully understandable.
 Other approaches are mentioned by the Tehilla Le-David (318:33) and the Chayei Adam (Nishmat Adam 20:8, 10).
 This is what the Magen Avraham (253:37), Shulchan Arukh Ha-Rav (253:25, also Piskei Ha-siddur, Hilkheta Rabbeta Le-Shabbeta) and the Beit Meir (318:12). This is also implied by the Chiddushim Ha-myuchasim La-Ran cited above (n. 4), that as long as the food has not cooled, there is no issue of cooking; this implies that if it cools, there is a biblical prohibition of bishul.
 This is also what arises from the words of the Terumat Ha-deshen (ch. 66). However, according to the view of many Rishonim, there is a prohibition to take something that is minimally cooked (maakhal ben Derusai) and cook it further (see note 8 in our first shiur), and this is what the Shulchan Arukh rules (318:4); however, in the view of the Eglei Tal, this prohibition is only rabbinical, and naturally the doubt here would be of a rabbinical nature, and we may rely on the lenient views that ein bishul achar bishul applies to liquids even if they have totally cooled.
 This is indicated by Rabbi Akiva Eger (on Magen Avraham, 253:41).
 This is stated by the Minchat Kohen (II, 2, s.v. Ha-tenai ha-rishon), the Arukh Ha-shulchan (318:31), the Ketzot Ha-shulchan (ch. 124; Baddei Ha-shulchan, 103); Rav Moshe Feinstein (2, 5); Rav S.Z. Auerbach (Shemirat Shabbat Ke-hilkhata, ch. 1, n. 114); and the Shevet Ha-Levi (Vol. V. Ch. 31, 1). The view of the Mishna Berura in this case is not clear: see 318:99 and Beiur Halakha 318:4, s.v. Im nitztanen.
 The Chazon Ish goes on to write that it may be that the stringency about a liquid that totally cooled stems from the laws of hachzara, but since we are totally lenient regarding a solid it appears that he does not accept this understanding.
 Is it appropriate for Ashkenazim to be stringent and follow the Sefardic ruling? The Mishna Berura (253:84) implies that it is good for Ashkenazim to be stringent and to follow the Shulchan Arukhs view that once a liquid is no longer yad soledet bo, it is halakhically uncooked. However, in other places, the Mishna Berura indicates that Ashkenazim should be lenient, and this is what appears to be the ruling of other authorities as well.
 According to this explanation, the Rema does not speak only of a situation in which a non-Jew performs an act of bishul, but even a situation in which there is no issue of bishul (because the food is not cold). However there is still a rabbinical prohibition, one of returning a cooked food to the fire (the specifics of this prohibition will be discussed in a future shiur); regardless, one may not benefit from the non-Jews actions.
 However, the Chazon Ish does imply another interpretation. He indicates that we follow the Rishonim who believe that yesh bishul achar bishul for liquids is a stringent custom that we have accepted upon ourselves, and this implies that fundamentally there is no problem. He also indicates that one should only be stringent about a cold item on Shabbat itself, but one who takes a cooled liquid and heats it a bit before Shabbat would be allowed to continue to heat it on Shabbat, though this is an innovation not mentioned by other halakhic authorities.