1. רוטב which is not congealed (re: combining for tumah vs. Yom Kippur)

The Mishnah on Daf 117b taught that רוטב – gravy combines with meat to transmit food tumah. Rava identifies רוטב as שומנא – fat, but Abaye objects that since fat is fully edible, it should be metamei on its own, without combining with meat!? Abaye therefore defines רוטב as חלב דקריש – congealed [liquid which exudes from the meat], which is not eaten on its own, but is eaten with the meat. The Gemara objects that even uncongealed fat combine with meat, because Reish Lakish said that liquid sap from greens combines with the greens for the shiur of ככותבת הגסה – the size of a large date on Yom Kippur!? The Gemara answers: התם משום יתובי דעתא הוא – there, the prohibition of eating on Yom Kippur is based on easing one’s mind from the affliction of fasting, and any kind of food, even liquid sap, can contribute to that relief. For tumah, however, “food” and “drinks” cannot combine (since they have different shiurim). Therefore, only congealed רוטב, which is classified as food, can be combined with the meat.

1. Liquified foods regarding cheilev, חמץ, etc.

A Mishnah teaches that one who dissolves cheilev and drinks it is liable. Although the prohibition is phrased as “eating,” and drinking liquified cheilev is not ordinarily considered “eating,” Reish Lakish explains that the passuk says "נפש" (which also connotes satisfaction or desire), לרבות את השותה – to include one who drinks liquified cheilev. A Baraisa teaches that one is liable for consuming liquified חמץ on Pesach, whereas one who consumes liquified מצה is not יוצא the מצוה, because liquified מצה does not qualify as "לחם עוני". Liability for consuming liquified חמץ, despite its prohibition being expressed as "אכילה", is likewise derived from the word "נפש" written there. A similar derashah teaches that one who consumes the liquified neveilah of a kosher bird becomes tamei, and another teaches that the juices from שרצים are forbidden like their meat. The Gemara explains why all these derashos are necessary, and discusses this principle regarding several other halachos.

1. Machlokes regarding the fruit juices of terumah

Rebbe Yose darshens that grapes which were pressed into wine are valid as בכורים, and a היקש extends this halachah to terumah. A Mishnah teaches that if a non-Kohen accidentally consumes terumah of date honey, apple cider, or vinegar of winter grapes, Rebbe Eliezer requires him to pay קרן וחומש – the principal plus a fifth (like any זר who mistakenly eats terumah), because he considers the juices of terumah like fruit. Rebbe Yehoshua exempts him from paying קרן וחומש for consuming these liquids.

Rebbe Eliezer holds דון מינה ומינה – derive the law from [the source] and derive the parameters from it. Just as with bikkurim, משקין היוצא מהן כמותן – the liquids which issue from them are like them, the same applies to terumah. And, just as bikkurim applies to other types of fruit (besides grapes and olives, since בכורים are brought from the שבעת המינים), so too the liquid terumah of other terumah fruits, such as dates and apples, is like the fruit itself (Rashi notes that such terumah is only מדרבנן). Rebbe Yehoshua holds דון מינה ואוקי באתרה – derive the law from it, but establish its parameters according to its own place. Since only wine and oil can be initially designated as terumah as liquids, only those liquids have the full status of terumah.