Related for Kiddushin 82:19

The son, and the hired hand, and the slave, and the wife separate terumah on what they eat, but they do not separate terumah on everything, as a person does not separate terumah on a thing that is not his. [However,] the son [may separate terumah from produce] belonging to father, and the wife [may separate terumah] of her dough -- behold, these [persons are allowed to] separate terumah because they are separating terumah with permission.

A Gentile that [separates] terumah -- his terumah is valid terumah (but see Ter. 1:1). In what case does this apply? [In the case of] a threshing floor, he separated terumah and gave it to a Kohen, [or separated] first tithes and gave them to a Levite [or separated] poor person's tithes and gave them to a poor person. [If his] produce is properly tithed [but] he brings his produce into his house, his produce is [considered] spoiled. An Israelite who is suspected of having brought his produce into his house, his produce [is considered] spoiled. A Samaritan is like a Gentile, the words of Rebbi. Rabban Shimon ben Gamaliel says, a Samaritan is like an Israelite.