Challah 2:5-6

Challah 2:5

If a person separates challah from flour (rather than dough), what he has separated does not count as challah and would actually be considered like stolen property when in the possession of the kohein (who did not receive it properly). The dough is still obligated in challah, as is the flour he gave the kohein if it is of a sufficient quantity. A non-kohein is not permitted to eat that flour because, even though the owner inappropriately designated it as challah, observers might mistakenly think that the non-kohein is eating actual challah. This is the opinion of Rabbi Yehoshua, but the Sages related an incident in which a learned non-kohein ate such flour. Rabbi Yehoshua acknowledged the incident but he said that the scholar in question was punished for his actions, though he benefited others who follow his example (in that they are acting in a state of ignorance by relying on him).

Challah 2:6

A kav and a quarter of flour (a little more than a half-gallon) is obligated in challah. The five grains, the leaven that ferments their dough, their fine bran and their coarse bran all combine so that a kav and a quarter total is obligated in challah. If the flour was sifted and the removal of the coarse bran causes the volume to drop below a kav and a quarter, then the coarse bran is added back in, restoring the original volume, the flour remains exempt from challah. (This is because it’s not usual for people to reintroduce coarse bran into sifted flour.)