Squeezing Out Lemon Juice into a Salad
It is permitted to squeeze out lemon juice into a salad in order to improve the taste of the vegetables*. One must squeeze the lemon directly on the vegetables (i.e., it is not permitted to squeeze out the lemon juice into a cup and then add it to the salad).
Squeezing out lemon juice into a salad is permitted even if the lemon juice will not be absorbed into the vegetables of the salad.
- Note: If lemon seeds will fall into the salad, one is not allowed to extract them (due to the prohibition of borer). As such, one is advised to squeeze the lemon in a way that the seeds will not come out (e.g., slowly, keeping the sliced part of the lemon tilted upwards).
The Mishna in masechet Shabbos (ch. 22 Mishna 1) states, “We don’t squeeze fruits (on Shabbos) to extract the juice from them”. Rashi explains that the extraction of juice involves the tolda of mefarek, a derivative of an av melacha (a principle action prohibited on Shabbos) of dosh. The melacha of dosh in the construction of the Mishkan was one of the steps in the preparation of bread (for the Lechem HaPonim), whereby the wheat stalks were trampled on in order to extract the kernels from their shells.
The removal of an edible part of food from an inedible part falls under the av melacha of Dosh. It’s tolda – Mefarek – is extracting a liquid from a solid. Thus, it is prohibited to squeeze fruit to extract its juice on Shabbos*.
The Gemora, (Shabbos 144b) however, makes the following statement: “One is allowed to squeeze a cluster of grapes into a pot (with food)”. There, the reason is given as follows: A liquid which is being extracted for the sake of a solid food (i.e. to improve the taste of the food – see Rashi ibid.) does not maintain the status of “liquid” (even at the time of extraction), but rather, it attains the status of “solid.” The halacha follows this ruling of Gemora (O.C 320:4). It thus permitted to squeeze lemon juice into a salad.
* Gemora, Rishonim and later poskim discuss at length which fruits fall under this prohibition. One is not allowed to squeeze certain fruits for their juice due to a Torah prohibition, for other fruits the prohibition is only Rabbinic, while others don’t fall under this prohibition at all and it is permitted to squeeze them on Shabbos to extract their juice. (To learn about the details of these distinctions, see the Shulchan Aruch O.C. 320:1, the Ram”a, and the Mishna Berura ibid.)