Tosefta zu Bamidbar 18:12

One who brings ears of grain inside his house in order to rub off the chaff (=מלילות, see Maasr. 4:5), behold, he [may] take terumah [of the ears of grain in that state]. A Levite for whom ears of grain were designated, to in the future make a threshing floor with them, [or] grapes to in the future make them into wine, [or] olives to in the future make them into oil -- just as the first terumah (Num. 18:12) is taken from the threshing floor and from the vat, so too the terumah of tithes is taken from the threshing floor and from the vat.