Spoiled And Rotten?
‘A Loaf Went Moldy’
The Gemara cites two baraisos that state that one is obligated to dispose of moldy bread before Pesach. The first baraisa explains that moldy bread must be discarded because it’s capable of leavening other breads (and therefore has significance).
The second baraisa states that it must be discarded because it’s still fit for animal consumption. If, however, it has spoiled to the extent that even a dog won’t eat it, it’s considered insignificant and may be kept in one’s house over Pesach.
Some Redeeming Value
The Ran (ad loc.) cites R. Shimon (Avoda Zara 67b), who derives from a pasuk that forbidden foods unfit for human consumption are not forbidden by the Torah. In light of this rule, the Ran asks why the baraisa requires one to discard spoiled bread that’s unfit for human consumption.
He answers that moldy bread is more significant than other rotting food because it can be used as a leavening agent for other bread (as the first baraisa states). The Ran supports this answer by noting that the Gemara (Betzah 7b) seems to say the Torah forbids eating sourdough on Pesach despite being inedible because it’s used as a leavening agent.
A Leavening Agent?
The Rabad (to Rambam, Hilchos Chametz U’Matzah 1:2) proposes a different answer. He says the baraisa is not referring to an ordinary loaf of bread but rather to a block of sourdough, which has significance as a leavening agent despite being unfit for human and even animal consumption. (The Tosefta [first chapter of Tractate Betzah] states: When is it called sourdough? When it’s unfit for consumption by a dog.) The Rabad evidently does not consider ordinary bread to be a leavening agent, as does the Ran.
The Minchas Baruch (siman 35) comments that the Rabad seemingly doesn’t rule in accordance with R. Shimon for he prohibits moldy chametz that’s unfit for human consumption (even though it’s not a leavening agent). Apparently, he holds that all forbidden foods remain prohibited even if they are rotting and unfit for human consumption.
Alternatively, the gaon Rav Chaim Ozer Grodzinski (Achiezer vol. 3, 5:2) explains that the Rabad accepts R. Shimon’s ruling and normally permits forbidden foods that have spoiled and are unfit for human consumption. However, the issur of owning chametz – bal yera’eh – is an exception to this rule and applies even to spoiled food unfit for human consumption because the prohibition of chametz goes beyond consuming forbidden foods.