Two practical halakhot you may not have known TB Shabbat 145

A discussion, which began on yesterday’s daf TB Shabbat 144b continues on today’s daf TB Shabbat 145, has great practical halakhic implications. “Rav Yehuda said that Shmuel said: A person may squeeze a cluster of grapes on Shabbat into a pot with food in it, and it is not considered squeezing a liquid but rather adding one food to another; however, he may not squeeze the liquid into an empty bowl. Rav Ḥisda said: From the statement of our Rabbi, Shmuel, we learn that one may milk a goat into a pot of food on Shabbat, because it is not considered to be the manner of squeezing that is prohibited as a subcategory of the labor of threshing; however, one may not do so into an empty bowl. The Gemara deduces: Apparently, he holds that liquid that comes into food is not considered liquid, but rather, it is food. (משקה הבא לאוכלין-אוכל הוא)” (Sefaria.org translation) The Gemara challenges this position on our daf but all challenges are refuted.

The forbidden labor of squeezing (סחיטה) is defined by separating food from its worthless matter (פםוֹלת), for example separating wheat from the chaff. After squeezing grapes for the juice into an empty bowl, what’s left of the grapes is worthless matter. That’s the very definition of the prohibited labor of squeezing. When squeezing the grapes into food, the juice is considered to be food that is added to the dish and not considered to be a liquid! This is codified by Joseph Caro, Shulkhan Arukh, Orekh Hayyim, 320:4.

I learned something new. As I understand it, one may squeeze a lemon on a piece of fish on Shabbat, but he still can’t make lemonade.

The Mishnah on daf 145b teaches another important and practical halakha which is ein bishul akhar bishu (אין הישול אחר הישול-literally no cooking after cooking). “MISHNA: Any salted food item that was already placed in hot water, i.e., cooked, before Shabbat, one may soak it in hot water even on Shabbat. And anything that was not placed in hot water before Shabbat, one may rinse it in hot water on Shabbat but may not soak it, with the exception of old salted fish and small salted fish and the kolyas ha’ispanin fish, for which rinsing with hot water itself is completion of the prohibited labor of cooking.” (Sefaria.org translation)

This means that one is allowed to reheat food on Shabbat. Of course, the issue is much more complicated than the Mishnah states. For example, there is a major disagreement whether reheating food on Shabbat only applies to solid food or includes liquids. How you reheat also matters. If you’re interested in delving a little bit deeper into this issue follow this link to Rabbi Chaim Jachter’s article: https://www.koltorah.org/halachah/ein-bishul-achar-bishul-by-rabbi-howard-jachter