3,642. Dough From Which Challah Has Not Been Taken

Hilchos Bikkurim 7:11

Let’s say that someone takes leavening from a dough from which challah was not taken and adds it to a dough from which challah was taken. He should bring another dough that, combined with this leavening, will be of a size that requires challah to be taken. He then combines this second dough with the dough from which challah was taken. After doing so, he takes from the second dough enough challah for it and the leavening. By doing so, he is taking challah from dough in the same place. If he doesn’t have another dough, then the whole first dough is considered like tevel (untithed produce) and he must take challah for the whole thing. The reason is because when tevel gets mixed with produce of the same kind, even the smallest amount renders the mixture prohibited.

Hilchos Bikkurim 7:12

When it comes to ritual purity and impurity, dough from which challah has not been taken is like secular produce rather than like challah. As we will see IY”H in Hilchos Shaar Avos Hatumah, second-degree impurity doesn’t cause third-degree impurity in secular produce. One may therefore render secular produce ritually unclean in Israel. Therefore, if there’s a ritually unclean dough and a ritually clean dough, one may take enough dough to be challah for both of them from a dough hasn’t had challah taken and put it between them near the ritually clean dough. He then stretches an egg-sized portion from the ritually unclean dough to the ritually clean dough so that he will be able to take challah in the same place.