Commentary for Terumot 11:2

סתויונת – grapes that do not ripen until the days of he autumn, and regularly made from them vinegar.

[A non-priest drank] honey of dates, wine of apples, vinegar from winter grapes, and all other kinds of fruit juice of terumah: Rabbi Eliezer makes him liable to repay their value and the fifth; But Rabbi Joshua exempts from the fifth.
Rabbi Eliezer declares [these] susceptible to uncleanness as liquids.
Rabbi Joshua says: the sages have not enumerated seven liquids as those that count spices, but rather they stated: seven liquids make things susceptible to uncleaness, whereas all other liquids do not make susceptible.
This mishnah deals with the halakhic status of various types of fruit juices made from terumah.
Section one: One should not use terumah to make these liquids, because these are not the usual way these fruits are eaten, and therefore it diminishes their importance. This is different from making wine from grapes or oil from olives, for that is what is usually done with grapes and olives, and in no way diminishes their value.
Rabbi Eliezer says that if a non-priest drinks one of these liquids, he is liable to pay back the value and the added fifth, as one always is when one eats terumah.
Rabbi Joshua exempts the non-priest from paying the added fifth because these liquids do not have the same rule that governs the fruits from which they came. Nevertheless, he has to pay back the value because he ate something that didn’t actually belong to him.
Section two: The mishnah now brings a related debate concerning fruit juices, namely whether they can make another food item susceptible to receiving uncleanness. Food cannot become impure unless it has come into contact with a liquid. The question is whether fruit juice counts as a liquid. As we saw in section one, Rabbi Eliezer treats fruit juice the same way he would treat wine or oil a non-priest who drinks them is liable to repay the value and the added fifth. So too here, food that comes into contact with one of these is susceptible to impurity.
Rabbi Joshua disagrees and holds that only the seven liquids listed by the rabbis, (dew, water, wine, oil, blood, milk, and bee honey) make foods susceptible to impurity. When the rabbis listed these liquids in Mishnah Makshirim (which we’ll get to eventually) they weren’t listing things in the way a spice makers list things, which was not accurate. Rather, their list was accurate and since fruit juice is not on the list, it can’t be put there.

ושאר כל מי פירות – except for wine and [olive] oil.

מחייב קרן וחומש – for a foreigner (non-Kohen) who inadvertently eats them, for it is considered to them as actual liquid heave-offering/Terumah.

ורבי יהודה פוטר – from the added fifth, but he is liable for the principle, and ab initio, it is forbidden to foreigners (i.e., non-Kohanim).

מטמא משום משקה – impure, and they defile, and make the seeds fit for Levitical uncleanness, like other liquids, as it is written (Leviticus 11:34): “[As to any food that may be eaten,] it shall become impure if it came in contact with water; as to any liquid that may be drunk, [it shall become impure if it was inside any vessel].”

כמוני פטמין (like those who count spices) – like this spice has eight bags of his spices that are not exact and he returns and adds to them, but the Sages, exactly counted seven liquids that these alone are impure and make impure and make it fit to receive Levitical uncleanness, and we don’t add to them. And the seven liquids that the Sages counted (see Tractate Makhshirin , Chapter 6, Mishnah 4) are: water, dew, wine, oil, bee’s honey, milk and blood. And the Halakha is according to Rabbi Yehoshua.