FOOD THAT LOST THE STATUS OF FOOD [food: Bitul]
(Mishnah): If a cow drank Mei Chatas (water mixed with ashes of the Parah Adumah, and it was still in its stomach after Shechitah), the meat is Tamei;
R. Yehudah says, the Mei Chatas is Batel in its stomach.
The Mei Chatas is Batel only regarding severe Tum'ah, but it retains light Tum'ah.
Question: This implies that the first Tana says that it retains severe Tum'ah. The Mishnah says that he is Metamei [only] the meat!
45a (Mishnah): If dough is in cracks in a kneading trough:
If there is a k'Zayis in one place, he must destroy it;
If not, it is Batel because it is so small.
Similarly, if one is Makpid about it (intends to remove it), it is a Chatzitzah regarding Tum'ah. If he wants it to stay there, it is like part of the trough.
45b (Beraisa): One must destroy moldy bread, for one can grind it up and use it to ferment other dough.
R. Shimon ben Elazar says, this is if it is being kept [for fermenting, which is] for the sake of eating. Kofes Se'or (a block of heavily leavened dough) that was designated to sit on it is Batel.
Inference: Only R. Shimon says that it is Batel. The first Tana holds that even 'Bitul' (designation for sitting) does not help for a k'Zayis.
Version #1 (Rav Nachman citing Rav): The Halachah follows R. Shimon.
Question: Rav Yitzchak bar Ashi said in the name of Rav that if one plastered Paneha (the faces of) Kofes Se'or with mud [to sit on it], it is Batel!
Answer: Amora'im argue about the opinion of Rav.
Version #2 (Rav Nachman citing Rav): The Halachah does not follow R. Shimon, for Rav Yitzchak bar Ashi said in the name of Rav that if one smeared Paneha with mud, it is Batel.
Chulin 73b: Even though a dangling limb will be [after Shechitah] Ever Min ha'Chai, which has a severe Tum'ah, meat that separates from it needs Hechsher.
129a - Question (Rabah bar Rav Chanan): Why is Hechsher needed for meat that separated from Ever Min ha'Chai? The meat already had severe Tum'ah through the limb it was on!
Answer (Rava): That was merely Shimush Ma'ase Etz. (It was not considered a food.)
(Rav Masnah): If one made a roof from vegetation, the vegetation (becomes Tahor and - some texts delete this) is considered like a roof;
If the house gets Tzara'as, the roof is Tamei. This Tum'ah is mid'Rabanan, for food is never an Av ha'Tum'ah.
Rejection: (It can be mid'Oraisa.) After making a roof from it, it is merely Shimush Ma'ase Etz.
Rambam (Hilchos Chametz 1:2): The Isurim of Chametz and Se'or (sourdough, which is used to ferment dough) are the same.
Ra'avad: They are the same only regarding the Shi'ur. If Chametz was ruined so much that a dog would not eat it, one need not do Bi'ur. One must do Bi'ur on such Se'or, for it can be ground and used to ferment many doughs, unless he designated it to sit on it and plastered its faces with mud. The Tosefta (brought on 45b) obligates Bi'ur on moldy bread because one can grind it up and use it to ferment other dough. It refers to bread of Se'or. One would not need this reason to obligate Bi'ur of moldy Chametz!
Magid Mishneh: The Rambam does not distinguish Se'or from Chametz. This is primary. The Gemara rules unlike R. Shimon ben Elazar, unless he plastered the faces with mud. A Beraisa teaches that if it is not proper for people to eat, but it is proper for dogs, it has Tum'as Ohel and it is burned with Tamei on Erev Pesach. Ge'onim exempt from Bi'ur what is not proper for dogs. The Beraisa of moldy bread must discuss when a dog can eat it. R. Shimon says 'this refers to what is destined to be eaten, but Kofes Se'or...' This shows that the first Tana discusses Chametz, and not Se'or. Also, Stam bread is proper bread, and not Chametz. Also the Ro'oh holds like the Rambam.
Rambam (2:15): If one designated Kipas Se'or to sit on it, if he plastered its faces with mud, it is Batel, and one may keep it.
Rosh (2:1): If Chametz was charred before the time (that Chametz becomes Asur on Erev Pesach), one may benefit from it. Some permit even eating it, for it is like mere earth. This is unreasonable. Even though Batlah Daito Etzel Kol Adam (he is unlike normal people), since he eats it, it is forbidden. Also Ri Bartzeloni says so.
Rosh (3:2): Rav taught that if one plastered dough in his house, he must do Bi'ur. R. Shimon ben Elazar says that Kofes Se'or designated to sit on is Batel, i.e. when it is repulsive.
Rashi (129a DH keshe'Shimesh): Tum'as Ever Min ha'Chai is not because the meat is a food. It requires a bone, sinews and meat. The meat is considered a food only after it separated.
Tosfos (18a DH Ha): The Mishnah says that the first Tana is Metamei [only] the meat, i.e. but not people and Kelim. The water is not an Av ha'Tum'ah, because it was disqualified through diverting his mind from it [when the cow drank it].
Question: If so, it should not have even light Tum'ah [for it requires Hechsher]! Meat that separates from Ever Min ha'Chai needs Hechsher, even though is was destined to have severe Tum'ah, since it cannot have the severe Tum'ah after it separates!
Answer (Tosfos): There is different, for it is mere Shimush Ma'ase Etz. We say so in Chulin 129a. Therefore, it needs Hechsher after it separates. Mei Chatas must be initially proper to drink, so its severe Tum'ah is not Ma'ase Etz. Therefore, even after it is disqualified, it retains Tum'as Mashkim.
Tosfos (45b DH Kofes): Even if the Kofes Se'or is proper to eat, since he designated it to sit on, and he does not keep it to eat it, it is Batel, just like regarding Tum'ah. If one made a roof from vegetation, the vegetation becomes Tahor. Its Tum'ah [if the house gets Tzara'as] is mid'Rabanan, for food is never an Av ha'Tum'ah. We reject this, for it is merely Shimush Ma'ase Etz. This connotes that it is proper to eat. Chachamim hold that Kelim lose their Tum'ah when they are changed even through a constructive action. R. Yehudah holds that only a destructive action is Metaher (Shabbos 52b). The Ri says that they argue similarly about Chametz.
Shulchan Aruch (OC 442:9): If one designated Chametz to sit on it and plastered it with mud, one may keep it during Pesach.
Beis Yosef (DH u'Mah she'Chasav Oh): The Tur rules like Rav Yitzchak bar Ashi, for according to Version #2, no one argues with him. According to Version #1, even though Rav Nachman argues with him, Rav Yitzchak is more stringent. Also the Rambam rules like this.
Beis Yosef (DH u'Mah she'Chasav v'Yesh): If Chametz was charred before the time (that it becomes Asur on Erev Pesach), the Ran permits eating it. The Rosh and Ri Bartzeloni forbid. The Tur holds that they argue similarly about Chametz that became moldy or was designated to sit on it.
Taz (8): One may not eat it. Even though it is not proper to eat, he (one who eats it) considers it proper. The Rosh says so. It seems that he agrees that mid'Oraisa he is exempt, for one who eats on Yom Kipur something improper to eat is exempt.
Kaf ha'Chayim (99): One is exempt only for Chametz that became moldy or was charred. It is no longer considered food. If it was destined to sit on and plastered with mud, one is liable for eating it, since it is intact. It is exempt only from Bi'ur, for he was Mevatel it through designation and plastering.
Mishnah Berurah (42): Plastering helps even if it is not ruined from eating. This is because it lost the status of a food. The Mechaber connotes that one must plaster it from every side. The Gemara says "he plastered Paneha." Perhaps he explains this to refer to the faces of the Kofes Se'or from every side.
Mishnah Berurah (43): Likewise, one may benefit from it. Mid'Rabanan one may not eat it until after Pesach. This is only if he wants to eat it, for he shows that he considers it a food. If Chametz that became improper for a dog fell into a food, even if the food is a mere majority (i.e. the spoiled Chametz is a large minority), one may eat the food, for the spoiled Chametz is like earth.
Kaf ha'Chayim (96): Rashi connotes that one must designate and plaster it. However, the Bach and Olas Shabbos hold that designation is not enough, but plastering alone suffices. It becomes repulsive, and is Batel automatically.