Orlah 2:9-10

Orlah 2:9

If regular leaven fell into dough and actually leavened it, then some terumah leaven or leaven of mixed species fell into the dough and it is enough to cause it to leaven, the dough is prohibited; Rabbi Shimon permits it.

Orlah 2:10

If spices from two or three of our prohibited categories (terumah, orlah and mixed species) are of the same type of produce, or if they are of three different types in the same category, they combine to render food prohibited. Rabbi Shimon says that spices of one type from two or three categories, or of two types from one category, do not combine.