Related על תרומות 3:4

A worker who separates terumah from the threshing floor [without explicit permission], his terumah is not [valid] terumah, but if the landowner said to him, "gather together [the produce] of my threshing floor," his terumah is [valid] terumah, as [the produce on] the threshing floor may not be gathered together unless terumah has [first] been separated.

From what time may they (i.e., the chaverim workers specifically designated to tithe the winepress, see Ter. 3:4 and Bartenura there) take terumah from the winepress [on behalf of the am ha'aretz owners]? After they tread on the [grapes in the vat both] vertically and horizontally. From what time do [the am ha'aretz owners enter and] render the winepress impure? Beit Shammai say, "After first tithe is removed [by the workers]." Beit Hillel say, "After second tithe is removed." Said Rabbi Yehudah, the halacha is according to the words of Beit Shammai; however, the multitudes have become accustomed to act according to the words of Beit Hillel. And the Sages say, [the workers] take out terumah and tithes and [the owners] immediately [enter and] render the winepress impure.