Challah 3:1-2

Challah 3:1

Before separating challah, one may snack from dough until it has been rolled (in the case of wheat) or kneaded until cohesive (in the case of barley). Once wheat dough has been rolled or barley dough has been kneaded, one who eats from it before challah has been taken is liable to a Divine death sentence. A woman should take challah as soon as she pours water on the flour unless there is a kav and a quarter of flour there (in which case challah cannot be taken until after the dough has been rolled).

Challah 3:2

If dough became meduma (forbidden to non-kohanim) before it was rolled, it is exempt from challah because meduma is exempt from challah. If it became meduma after it was rolled, the dough is still obligated in challah. If there’s a doubt about ritual uncleanliness that arose before it was rolled, the dough may be made in a state of uncleanliness. If the doubt arose after it was rolled, it must be made in a state of cleanliness.