(Mishnah): One may not separate Terumah from oil for crushed olives, nor from wine for crushed grapes (as one is separating from something completed for something that is not). If he did, it is valid, but he must separate Terumah again.

The first Terumah prohibits when a small amount fell into Chulin (if there aren't 100 parts Chulin to negate it and if a non-Kohen would eat it), he would need to add an extra fifth to the value. These do not apply to the second Terumah.

One may separate oil for pickled olives or wine for grapes that will be made into raisins.

One who separated oil for olives that will be eaten or olives for olives that will be eaten, or wine for grapes that will be eaten or grapes for grapes that will be eaten and then decided to press them, he does not need to separate Terumah again.

One may not separate from a completed produce for an uncompleted produce or vice-versa, or from an uncompleted produce for an uncompleted produce; but if he did, it is valid.

(Gemara) Question: The end of the Mishnah taught that one may not separate from completed produce for uncompleted produce. But the beginning of the Mishnah taught that it is valid but he must separate again...?

Answer (R. Ila citing R. Yochanan): At the beginning of the Mishnah, the Rabbanan required separating again to prevent the negation of the Parah Adumah waters. (They required separating again as they were concerned that a person might always press a small amount of oil and then separate it as the Terumah of all his olives (rather than first press all of them) - thereby avoiding the need to be careful with the Taharah of the rest of his oil. This might ultimately lead to a lack of care with Taharah in general and might thereby negate the usage of the Parah Adumah.) (Note: This entry follows the explanation of the Vilna Gaon in Shnos Eliyahu, as quoted by the Ridbaz.)

Question: Which is more stringent - loss to the Kohanim or negating the Parah Adumah? (The earlier Mishnah (Mishnah 2 - Chulin 56) taught that if one separated olives for oil, Beis Hillel say that it is not valid. R. Yochanan there explained that there was a concern for loss to the Kohanim (as explained there). Here, they were concerned for negating Taharah.)

Answer (Tosefta): 'If one separates olives for olives that are for pressing or grapes for grapes that are for pressing, it is valid Terumah, but he must separate again.' Both the reasons of loss to the Kohanim and negating Parah Adumah are relevant here, but the Tosefta taught that he must separate again. This shows that the more stringent concern is negating the Parah Adumah.

Question: According to R. Yosi (who said in Halacha 2 that according to Beis Hillel, one who separates olives for oil, it is invalid Terumah, since he has caused a loss to the Kohanim), would he say the same in our Mishnah that he should also be penalized because of the Parah Adumah concern and he should separate Terumah again?

Answer (Baraisa from R. Yosi): R. Meir - One may not separate from oil for olives or from wine for grapes. If he did, it is valid, but he must separate again.

(R. Yosi): Beis Shammai permit separating in this way. Beis Hillel do not permit it. Both agree that if it was taken in this way, it is valid and Terumah need not be taken again.

There are differing opinions - R. Meir is lenient about loss to the Kohanim but is stringent about negating the Parah Adumah. R. Yosi is stringent about loss to the Kohanim but is lenient about negating the Parah Adumah.