Maaseros 2:3-4

Maasros 2:3

If a person transports untithed produce from the Galilee to sell in Judea, or if he brings it with him to Jerusalem, he may snack on it until he reaches his destination; he may do likewise on his return journey. Rabbi Meir says he may eat from the produce until he reaches the place where he will spend Shabbos. Traveling salesmen who move from town to town may eat from such produce until they reach the place where they will spend the night. Rabbi Yehuda says that the first house a salesman reaches obligates him in tithes.

Maasros 2:4

If a person separated terumah before completing the work that obligates the produce in tithes, Rabbi Eliezer does not allow him to snack from it until he has taken the tithes; the Sages permit it except in the case of a large basket of figs (which in their opinion is exactly the thing that obligates it in tithes). If he separated terumah from a large basket of figs, Rabbi Shimon permits one to snack from it and the Sages prohibit it.