One who puts aside produce to separate terumah and tithes with them, [or] money to separate the second tithe with them, may separate with them on the assumption that they are still in existence. If they were lost, he must be cautious regarding a period of twenty-four hours —- [these are] the words of R' Elazar ben Shamua.  R' Yehudah says: At three points in time the wine must be examined: at the time of the east wind [which is] after the Festival, with the emergence of the budding berries, and at the time that liquid enters the unripe grapes.