OPINIONS: The Gemara says that even the Rabanan -- who maintain that dough kneaded with Mei Peros (fruit juice) does not become actual Chametz -- agree that the dough is considered Chametz Nuksheh. What exactly is the case that the Gemara is discussing?

(a) RASHI in Pesachim (36a, DH Ein Lashin) explains that the Gemara refers to flour that was kneaded solely with Mei Peros, without the addition of water. The Rabanan maintain that the dough cannot become Chametz Gamur, but it nevertheless becomes Chametz Nuksheh. This is why the Mishnah says that flour that was kneaded with the extract of an apple of Terumah is forbidden as Terumah because the juice causes it to rise.

It is for this reason that one may not knead flour with Mei Peros during Pesach. Although Mei Peros does not cause dough to become Chametz Gamur, it does cause it to become Chametz Nuksheh, if the dough was not watched ("Shemirah") to ensure that it does not become Chametz. Moreover, Rashi says that flour kneaded with Mei Peros becomes Chametz Nuksheh even faster than it becomes Chametz when kneaded with water, and therefore Shemirah will not help.

(b) RABEINU TAM, cited by TOSFOS (DH Ein Machmitzin), argues with Rashi and says that Mei Peros does not cause dough to rise at all. According to Rabeinu Tam, flour that is kneaded with Mei Peros and is left (without being baked) for a whole day does not become Chametz Nuksheh.

According to Rabeinu Tam, the Gemara is not discussing a dough made from flour and Mei Peros alone, since such a dough would not even be Chametz Nuksheh. Rather, the Gemara is discussing a dough that was made from flour and water, to which Mei Peros was added before it became Chametz. In this case, the leavening is caused by the Mei Peros together with the water, and thus it becomes only Chametz Nuksheh and not Chametz Gamur. When the Mishnah discusses the extract of an apple of Terumah, it refers to dough that was kneaded with water as well as with the apple extract. Since the apple extract causes the dough to rise, it gives the dough a status of Terumah.

The ME'IRI in Pesachim points out that the words of Rabeinu Tam are consistent with the Mishnah and Beraisa cited by the Gemara here. The Beraisa says, "Ein Machmitzin b'Tapuchim" (we do not make dough rise with apple extract). If the Beraisa refers to dough that was kneaded only with Mei Peros and not with water, then it should say, "Ein Lashin b'Tapuchim" (we do not knead with apple extract). The wording of the Beraisa implies that the dough was already formed before the apple extract was added. Similarly, the Mishnah regarding Terumah discusses an apple that is crushed and "put into dough," implying that the dough was already made (with flour and water) when the apple was added to it.

(c) The RAMBAM (Hilchos Chametz u'Matzah 5:2) writes that flour kneaded with Mei Peros, with no water, will never become Chametz, "because Mei Peros does not cause bread to rise, but rather it causes bread to rot." The Rambam adds that this is true only when no water is ever added. If even a minute amount of water is added, then the dough will become Chametz.

The Rambam clearly rules like Rabeinu Tam's understanding of the Rabanan when he writes that flour kneaded with Mei Peros does not become Chametz at all. However, the Rambam also writes that if any amount of water is added, then the dough will become Chametz Gamur, and not merely Chametz Nuksheh. This ruling is consistent neither with the opinion of the Rabanan according to Rabeinu Tam, nor with the Gemara. How does the Rambam understand the Gemara here that says that dough kneaded with Mei Peros becomes Chametz Nuksheh according to the Rabanan?

1. The BRISKER RAV writes that the Rambam explains the Gemara differently from the other Rishonim. The Gemara questioned the view of the Rabanan from the Mishnah (Terumos 10:2) that says that a dough that was leavened with an apple of Terumah acquires the status of Terumah. If Mei Peros cannot cause a dough to leaven, then the apple of Terumah in the dough should be Batel and not cause the dough to become Terumah (since only if it causes the dough to rise is it recognizable and not Batel). The Gemara answers that although the Mei Peros does not cause the dough to become Chametz Gamur, it nevertheless has a recognizable affect on the dough. According to the Rambam, this recognizable affect is not that it makes the dough become Chametz Nuksheh, but rather it is some other action that the Mei Peros does to the dough that makes it recognizable (and thus not Batel).

Accordingly, the Rambam learns that the Gemara is discussing dough kneaded with Mei Peros without any water, and it is called Nuksheh only with regard to the laws of Terumah but not with regard to the laws of Chametz on Pesach.

2. Another way to understand the Rambam is as follows. The Rambam rules that Mei Peros together with even a drop of water causes dough to become Chametz Gamur. The water helps the Mei Peros act upon the dough. However, in the case of the Gemara here, the water does not mix with the Mei Peros. As the Me'iri writes, the simple reading of both the Beraisa and the Mishnah quoted by the Gemara here is that a dough was already formed that was kneaded with water, and now Mei Peros is being added to that dough. In this case, the water cannot help the Mei Peros cause the dough to become Chametz, since the Mei Peros is being added after the dough was already kneaded with water. However, the Gemara teaches that, in such a case, the water does help the Mei Peros cause the dough to become Chametz Nuksheh. Consequently, if the Mei Peros is Terumah, then it will cause the dough to have the status of Terumah.

According to this explanation, the Rambam learns that the Gemara here refers to adding Mei Peros to a dough that was formed by mixing flour and water. The Gemara rules that the Mei Peros causes the dough to become Chametz Nuksheh, and not Chametz Gamur. The Rambam's words do not contradict this. When dough is made by mixing flour with only Mei Peros, the dough will not become Chametz at all, even Chametz Nuksheh. If water is mixed with the Mei Peros, though, then the Mei Peros will cause the dough to become Chametz Gamur. (Mordechai Zvi Dicker)

QUESTION: The Gemara conclusively refutes the opinion that maintains "Yesh Dichuy b'Isurim" from the Mishnah in Taharos (3:4). The Mishnah states that if a k'Beitzah of food, a k'Zayis of Tum'as Mes or Neveilah, or a lentil's size of a Sheretz was left in the sun and shriveled to less than a Shi'ur, it loses its ability to be Metamei. Similarly, if a k'Zayis of Chelev shriveled to less than a Shi'ur and one eats it, he is not liable for eating Pigul, Nosar, or Chelev. However, if it was left in the rain and returned to its original size, then it becomes able to be Metamei again and one is liable for eating it. This Mishnah clearly shows that "Ein Dichuy b'Isurim."

The KESEF MISHNEH (Hilchos She'ar Avos ha'Tum'ah 4:13) quotes the MAHARI KURKUS who questions the Gemara in Shabbos (91a) based on the Gemara here. The Gemara in Shabbos discusses a case in which a person picked up a fig in Reshus ha'Rabim, and the fig then became smaller, but before he put it down (Hanachah) in Reshus ha'Rabim it returned to its original size. The Gemara asks whether there is "Dichuy" for Isurim; perhaps the person is not Chayav for carrying it in Reshus ha'Rabim, since the fig lost its Shi'ur in the midst of the Melachah of Hotza'ah. The Gemara leaves its question unanswered.

Why does the Gemara there not answer its question of whether there is "Dichuy" for Isurim from the Mishnah quoted by the Gemara here? Just as the Gemara here proves from the Mishnah in Taharos that "Ein Dichuy b'Isurim," the Gemara in Shabbos should also prove from there that "Ein Dichuy b'Isurim"!

(a) The VILNA GA'ON (Bi'ur ha'Gra OC 486) suggests that when the Gemara here proves that "Ein Dichuy b'Isurim," it actually means that the topic of Dichuy is not relevant at all with regard to questions about the Shi'ur of an item of Isur or Tum'ah. This is because an Isur depends on the size of the object at the present time. The fact the object had a smaller size in the past is of no relevance. The only situation in which Dichuy is relevant is in cases of Mitzvos or Kedushah, where there is a question whether an object that became Pasul for a Mitzvah can become fit again for the Mitzvah. In such a case, perhaps the Pesul remains even after the object becomes fit again for the Mitzvah. In contrast, an object of Isur or of Tum'ah does not need to become "fit" for something. All that matters is that the object is large enough right now to be Asur or to be Metamei.

The Vilna Ga'on adds that according to this explanation of the Gemara, an object that was smaller than the Shi'ur of Isur or Tum'ah but swelled up to the proper Shi'ur is also considered an object of Isur or Tum'ah, because what is relevant is only what the size of the object is now, and it does not matter that the object was not Asur before it reached this size. (See also CHIDUSHEI HA'GRIZ.)

Based on this approach, the Vilna Ga'on answers the question of the Mahari Kurkus. In the case of the Gemara in Shabbos, the topic of Dichuy is relevant. There, the person's act began with an object large enough to make him liable for Hotza'ah, but in the middle of his act the size of the object decreased. Although the object later returned to its original, full size, perhaps the person is not liable since the Melachah was "pushed off" from being a Melachah for which one is liable, and the person's act no longer can be considered a Melachah.

However, all of the Rishonim seem to learn differently. The Vilna Ga'on himself quotes the Rambam (ibid. 4:14) who rules that if the object of Tum'ah originally had less than a Shi'ur of a k'Beitzah, and then its size increased to a k'Beitzah, it is Metamei only mid'Rabanan, as the Gemara here (54a) says. According to the Vilna Ga'on, the Gemara's conclusion is that the previous Shi'ur of the object is not relevant when it comes to Isur and Tum'ah; as long as the object presently has a Shi'ur, it is Asur or Metamei. The Vilna Ga'on quotes other Rishonim who seem to learn differently, and he concludes that he is not in a position to rule leniently, in opposition to those Rishonim.

(b) The KEREN ORAH offers a different explanation. He agrees that the Gemara's conclusion that "Ein Dichuy b'Isurim" means that Dichuy is not relevant for Isurim. He also agrees that the question of Dichuy applies only with regard to an object that needs to be fit for a Mitzvah or for Kedushah. However, he asserts that with regard to Isur and Tum'ah, it is not enough to take into account the object's present size. If the object was originally small and it increased in size due to the absorption of moisture, mid'Oraisa the increased size is considered artificial, and the actual Isur is still the smaller size. However, mid'Rabanan the new size is taken into account, and the object will be Metamei mid'Rabanan (as the Gemara on 54a says). This is consistent with the ruling of the Rambam that if the object of Tum'ah originally had less than a Shi'ur of a k'Beitzah, and then its size increased to a k'Beitzah, it is Metamei only mid'Rabanan.

The Gemara here concludes that "Ein Dichuy b'Isurim," and thus an object that was large, became smaller, and then returned to its original size is still Asur or Metamei as it was originally. The present growth is considered to be real and, mid'Oraisa, it is Metamei. In contrast, in the case of the Gemara in Shabbos, the Melachah must be fit to make the person liable, and, as the Vilna Ga'on explains, since at one point during the Melachah the object did not have a Shi'ur, perhaps "Yesh Dichuy" and the person is not liable.

(It is clear from the Keren Orah's explanation that he would not agree with the ruling of RAV MOSHE FEINSTEIN zt'l, who rules (Igros Moshe OC 1:71) that if one eats an object of Isur that grew from the size of a single k'Zayis to the size of two k'Zeisim, he will be Chayav mid'Oraisa for eating each k'Zayis. Rav Moshe explains that this is because the food never lost its status of Isur, since it always was at least the size of a k'Zayis. Rav Moshe learns that the difference between whether the object originally had a Shi'ur or it did not have a Shi'ur is whether or not it had the status of an Isur. If the object originally was the size of a k'Zayis, then the Isur took effect. The Keren Orah, however, learns that the difference is whether the increased size of the object was due to an artificial expansion (such as due to the absorption of water), or the object itself actually grew. It does not matter how large the object was originally. If only a k'Zayis is eaten, one will be Chayav only mid'Rabanan and not mid'Oraisa, as the Gemara says on 54a.) (Mordechai Zvi Dicker)