Beit Midrash

  • Pesach
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Chapter Two-Part Two

The Definition of Leavening Dough


Rabbi Eliezer Melamed


4.The Definition of Leavening Dough

As we have learned, the difference between bread and matza is that the dough used for making bread has undergone a leavening process resulting from the fermentation of ingredients within the flour that have come into contact with water. In order to augment the leavening process, bakers customarily mix se’or into the dough, causing the dough to ferment more thoroughly and quickly. However, even without the leavening agent, if dough were left without kneading, it would ferment and rise. Therefore, when preparing matzot one must work quickly to ensure that the leavening process within the dough does not begin.
As long as the dough is in motion, being kneaded, it does not become ĥametz. Even if the kneading were to continue an entire day, the dough would not become ĥametz, since kneading inhibits the leavening process. However, if the dough sat motionless for eighteen minutes, the leavening process has begun and all the prohibitions concerning ĥametz apply to it. This applies to normal conditions, but where it is hotter, the leavening process is accelerated, and the dough becomes ĥametz in even less than eighteen minutes.
Cracks appearing in the dough are a physical indication that the dough has become ĥametz. Even if eighteen minutes without kneading had not yet passed, since there are cracks in the dough, it has certainly become ĥametz; apparently conditions were warm and so it took less time to become ĥametz. Moreover, the kneading may have been inadequate, so that certain parts of the dough were neglected, causing those areas to become ĥametz. Even if there are only a few cracks, and they appeared only in part of the dough, the entire dough is ĥametz. If no cracks appeared but the dough blanched, it is ĥametz nuksheh (hardened ĥametz; see next section), which is rabbinically forbidden (SA 459:2). 3
5.Ĥametz Nuksheh (Hardened Ĥametz)
The ĥametz that the Torah forbade is ĥametz gamur (absolute ĥametz), meaning that the leavening process has been completed, and the food has become edible. But if fermentation had begun but not concluded, and from the outset the food was barely edible, then it is called "ĥametz nuksheh." According to most poskim, ĥametz nuksheh is not forbidden by Torah law, but the Sages prohibited it so that people would not err and come to eat or keep real ĥametz.
An example of ĥametz nuksheh is the glue that scribes used to prepare from flour and water for gluing paper. Since its leavening process was never completed, and it is barely edible, it is ĥametz nuksheh, and the Sages forbade eating it or keeping it on Pesaĥ (MB 442:2). If its form was changed, as when the glue is used to stick papers together, then one is allowed to keep it. Others are more stringent and maintain that if the glue protrudes from between the pages, then it is considered as if it has maintained its same form, and it is forbidden to keep it on Pesaĥ (SA and Rema 242:3).
Similarly, dough that began to ferment to the point that its surface blanched, but the surface was not cracked as with true leavening, is considered ĥametz nuksheh, and it is forbidden by rabbinic law to eat or keep it on Pesaĥ (SA 459:2). 4
6. Ĥametz So Spoiled That a Dog Would Not Eat It
Ĥametz that was originally fit for eating, but that became moldy or spoiled to the point that it is not fit for human consumption, is still considered ĥametz gamur, since it can still be used as a leavening agent. In other words, even though, in general, all forbidden foods become no longer forbidden once they are no longer fit for human consumption, ĥametz is different. Since it can still help in the preparation of food, it is like se’or, which serves as a leavening agent and is therefore considered ĥametz. However, if it became so spoiled that it is not fit for consumption by a dog, then it is not considered food at all. Therefore, the law of ĥametz does not apply to it and it is permissible to keep it during Pesaĥ and to gain benefit from it (SA 442:2; MB ad loc. 10). By rabbinic decree, however, it is still forbidden to eat it on its own, for one who eats it – even though he is doing something very unusual – demonstrates that he still considers this ĥametz to be food (MB 442, 43).
The yardstick of being fit for a dog’s consumption is relevant only for measuring the spoilage of ĥametz or se’or. But if se’or was not spoiled, but only became so sour that it is not fit even for a dog, since it is good se’or (that functions as a leavening agent and is usable like regular yeast), all the laws of ĥametz apply to it, and one is required by Torah law to destroy it (BHL 442:9).
This law – that one does not have to burn ĥametz that was spoiled to the point of not being fit for a dog’s consumption – applies only if it became spoiled before the time that ĥametz becomes prohibited. But if it was fit to be eaten by a dog when the prohibition of ĥametz began, then even if it became spoiled later, to the point of not being fit for a dog’s consumption, one must burn it. Once the mitzva of eliminating the ĥametz is in effect, one does not discharge his obligation until he has destroyed the ĥametz completely (MB 442:9; see below, ch. 5, n. 5). 5
Note that all of these laws are conditional on the ĥametz having initially been fit for human consumption, or for preparing food for humans as se’or. If, however, it was not fit for human consumption at all from the beginning, then even if it was fit to be eaten by a dog, no prohibition applies to it. If from the beginning it was not intended for consumption, but it was in fact barely fit for human consumption, then it is ĥametz nuksheh, as described above.
7.Ways in Which There Is No Leavening
As noted, there are five types of grain that can become ĥametz after touching water. However, if they are roasted in fire, they can no longer become ĥametz, and in principle they may be mixed with water. Nevertheless, the Sages were concerned lest the roasting not be thorough, and thus the grain would become ĥametz when coming into contact with water. Therefore, one must treat them just as one treats regular cereal grains. If they became wet and eighteen minutes passed, we suspect they may have become ĥametz, and it is forbidden to gain any benefit from them, and one must destroy them (SA 463:3; MB ad loc 7).
The above concerns kernels of grain that were roasted in fire, but if it was flour that was roasted, there are Rishonim who are lenient, maintaining that one need not suspect that the flour was not roasted well. Thus, it is permissible to mix such flour with water or in a cooked food without concern for ĥametz (Rashi, Rambam). However, many Rishonim hold that in the case of flour, as well, one must be concerned that it may have not been roasted thoroughly (Rabbeinu Yeruĥam, Hagahot Sefer Mitzvot Katan, Hagahot Maimoniyot, and others). The Aĥaronim rule that one must not mix roasted flour with water or in a cooked food, lest it become ĥametz. Nevertheless, if one did make such a mixture, even though it is forbidden to eat it, it is permissible to keep it until after Pesaĥ and to eat it then (MB 463:8; Kaf Ha-ĥayim ad loc. 13).
However, concerning matza that was properly baked, it is agreed that it cannot become leavened again. Accordingly, it is permissible to soak matza and matza meal in water, and, indeed, this is what most people do. Ĥasidim, however, customarily do not eat soaked matza (see below 8:2).
Scalding the grains or the flour in boiling water also destroys the capacity for becoming ĥametz. However, the Ge’onim prohibited doing so, for today no one knows how to do this scalding, and if the boiling does not destroy the potential for becoming ĥametz, an opposite process of rapid fermentation may be generated, as heat may hasten fermentation. Therefore, scalded grains or flour are treated just like ĥametz: it is forbidden to gain any benefit from them and one must burn them (SA 454:3; MB 13).
Flour on which water dripped, drop by drop, continuously, even all day long, does not become ĥametz, since the falling of the drops disturbs the flour and shakes it, and does not allow the leavening process to develop. Immediately upon cessation of the dripping, one should knead the dough and bake it. If there is doubt that some of the dripping may not have been continuous, then this is a doubt concerning a law of Torah, and one must relate to that flour as ĥametz and burn it (Pesaĥim 39b; SA 466:6).
Another way to prevent the dough from fermenting is by soaking it in cold water (Pesaĥim 46a; SA 457:2). Preferably, one should not do so, lest the water not be cold enough, allowing the dough to ferment (Rosh, MB 454:18). 6
Flour that was kneaded with fruit juice does not become leavened at all, but if even a little water was added to the mixture, then it will become leavened (matza ashira will be explained below [8:1]).

^ 3.. The rising of the dough indicates that it has become ĥametz (Me’iri), and other symptoms, namely, cracks in the dough, a blanched appearance, and the time that has elapsed, are only relevant in a case where the dough did not begin to rise. However, there are situations in which the dough rises but this does not indicate that it has become ĥametz; rather, it has undergone what the Sages call "sirĥon" (spoilage). This applies to the case of rice, or of flour mixed with fruit juice, according to most poskim. However, when wheat flour mixes with water and begins to rise, this is in fact a sign that the mixture has become ĥametz. If the dough sat and was not kneaded for the time that it takes to walk one mil, it has become ĥametz even if there is no visible indication, as explained in the Mishna and Gemara in Pesaĥim 46a. SA 459:2 explains that this amount of time is eighteen minutes, although Rambam and R. Ovadia of Bertinoro maintain that it is twenty-four minutes. BHL ad loc. rules that these lenient positions may be relied upon to prevent a significant loss of money, and that the authorities rule according to the Shulĥan Arukh without even mentioning the more lenient opinion because of the strict nature of the prohibition of ĥametz.
According to Rashi and Me’iri, however, one must check the amount of time that the dough has been sitting only when it is unclear whether or not the leavening process has begun: if more than the time it takes to walk one mil has elapsed, the dough is ĥametz, and vice versa. If one is certain that the dough is not ĥametz, even if it has been sitting for longer than the time that it takes to walk one mil, it is not considered ĥametz. Nonetheless, according to most Rishonim in any situation where the dough has sat for longer than it takes to walk one mil, the dough is ĥametz. See, for example, MT, Laws of Ĥametz and Matza 5:13; SA 459:2. Pri Megadim’s introduction to §467 contends that such dough is complete ĥametz; eating it on Pesaĥ incurs the punishment of karet. Rashbatz writes that one must suspect that such dough has become ĥametz. In a warm place, dough becomes ĥametz in less than the time it takes to walk a mil, as written in Aguda in the name of the Ge’onim. This is the halakhic consensus, as it is also the ruling of Yerei’im, Mordechai, and Hagahot Maimoniyot. Additionally, Rosh writes that even if the dough became warm in one’s hands, the dough will become ĥametz more quickly. This is cited in SA and Rema 459:2 (see also Birur Halakha 46a). Although there is dispute as to whether or not the "sitting times" of the dough are combined, Terumat Ha-deshen rules that a full kneading of the dough cancels the previous sitting time, though merely poking the dough would not be effective. This is cited in MB 459:16.
Pesaĥim 48b states: "as long as the dough is being worked it cannot become ĥametz." The vast majority of Rishonim, including Rambam in Laws of Ĥametz and Matza 5:3 and Tur and SA 459:2, explain that as long as one keeps kneading the dough it will not become ĥametz, even if he does so for the entire day. Yet it appears that the Yerushalmi disagrees with the Bavli and says that if one kneaded the dough for the amount of time that it takes to walk four mil, the dough is considered ĥametz. Baĥ cites Ri’az that ideally we should act in accordance with the Yerushalmi. There is an even more stringent opinion – Ritva’s – according to which as long as one kneads the dough at the appropriate pace so that he will complete the kneading in less time than it would take to walk one mil, the dough does not become ĥametz. However, if the kneading goes on for longer than this time, the dough is considered ĥametz (see Birur Halakha on Pesaĥim 48b; Encyclopedia Talmudit, s.v."ĥametz," §5, pp. 74-75). Even though the vast majority of poskim disagree with Ritva, they rule that it is still preferable to be stringent and complete the kneading process within eighteen minutes, as explained in AHS 459:7.
^ 4.. The opinion of SA 447:12 is that ĥametz nuksheh is only rabbinically forbidden, and therefore, ĥametz nuksheh that existed over Pesaĥ is not forbidden after Pesaĥ. This is also the opinion of SAH 442:20-21 and MB 442:2, based on the opinion of most Rishonim. However, several Rishonim are of the opinion that ĥametz nuksheh is forbidden by Torah law. There are two related issues: the prohibition of eating ĥametz nuksheh and the prohibition of keeping ĥametz nuksheh (see Birur Halakha on Pesaĥim 48b regarding the issue of eating, and 42a regarding the issue of keeping it over Pesaĥ). See also the Encyclopedia Talmudit entry "Ĥametz Nuksheh" p. 108 (definition) and pp. 110-115 (extent of the prohibition). According to Rabbeinu Tam and many other poskim, flour that is mixed with fruit juice and a little bit of water is also considered ĥametz nuksheh. See below (8:1) regarding matza ashira.
^ 5.. MB 442:44 cites Ĥok Yaakov, which quotes Terumat Ha-deshen that if a gentile prepared ĥametz on Pesaĥ and then made it inedible even for dogs, it is prohibited for a Jew to gain any benefit from it, since it had been proper ĥametz during a time when ĥametz was forbidden. See also Igrot Moshe OĤ 3:62, which is lenient in this matter. Yeĥaveh Da’at 2:60 summarizes the opinions regarding this issue. See also Bedikat Ĥametz U-vi’uro 2:27-32, which explains this topic at length, and in n. 87 explains that according to Rambam and Rosh, ĥametz that became inedible for humans and is still edible for dogs but would not cause any other dough to become ĥametz need not be burned; Raavad disagrees. See AHS YD 103:1-5 regarding other forbidden foods that are no longer prohibited when they become unfit for human consumption.
^ 6.. Does freezing the dough halt the leavening process? Igrot Moshe OĤ 3:59 states that one may not assume that freezing halts the process, since perhaps the cold just slows down the leavening process but does not stop it completely. On the other hand, Ĥelkat Yaakov 3:166 and Devar Yehoshua 2:58 are lenient based on the fact that freezing the dough stops the leavening process completely. Nevertheless, one should not purposely prepare dough to freeze and bake on Pesaĥ, but if one prepared dough before Pesaĥ and did not have a chance to bake it before Pesaĥ, as long as the dough has not yet risen, he may freeze the dough and bake it after Pesaĥ.
All of the processes that slow the leavening process are summarized in the Encyclopedia Talmudit entry "Ĥametz" pp. 83-89. And even though we generally are not lenient when it comes to scalding the dough, there are practical applications when dealing with a dangerously sick person, where it is better to minimize the number of prohibitions involved, as explained in MB 454:13.

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