Related sur Halla 3:18

Untithed produce that gets mixed up with chullin, behold, this is forbidden [to eat] in any amount. If he had a supply in another place (cf. Challah 3:8), he can take it according to his calculation [of the amount that got mixed up], and if not, he takes all the chullin in an amount equivalent to the [estimated amount of] terumah [and] tithes in the untithed produced. And similarly, with tithes from which terumah has certainly not been taken that become mixed up with chullin, behold, this is forbidden [to eat] in any amount, and if he had a supply in another p[lace, he can take it according to his calculation, and if not, he takes the chullin according to the [estimated amount of] terumah of tithes [that needed to be separated].

Untithed produce that gets mixed up with chullin, behold, it is forbidden in any amount. If he has another batch [of produce] in a different location, he may take it out according to the calculation, and if not, Rabbi Eliezer ben Arakh says, he designates the terumah of tithes that are inside [the mixture] and he lifts it up at one hundred and one [to one]. And so too with tithes taken from untithed produce that got mixed up with chullin, behold, it is forbidden in any amount. If he has a batch in a different location, he may take it out according to the calculation, and if not Rabbi Eliezer ben Arakh says, he designates the terumah of tithes that are inside [the mixture] and he lifts it up at one hundred and one [to one]. And if it was untithed produce of first tithe or second tithe, behold, it is forbidden, as they did not permit a doubt as to a forbidden mixture except as to something that has permissible factors (i.e., where it is possible that all of the resulting produce may be consumed). Rabbi Shimon says, any matter that has permissible factors, such as untithed produce and second tithe, or consecrated produce, or new produce, the Sages did not provide a fixed measurement [to nullify it]. And any matter that does not have permissible factors, such as orlah and mixed-kinds of the vineyard, the Sages game them a fixed measurement [by which the mixture could be nullified]. They said to him, and what about seventh-year produce that does not have permissible factors but the Sages did not give it a fixed measurement [to be nullified if mixed with other produce]? He said to them, seventh-year produce [mixed with other produce] is not forbidden in any amount, rather it must be removed (biur), but to eat it they did not forbid it except if it imparts taste [to other foods].