Dear Rabbi Kornfeld:
This issue came up during a study discussion here in Houston: Whereas the Mechaber says it's OK to squeeze out lemon juice (into a liquid---since it's understood that squeezing onto solids is not problematical) on Shabbat, later authorities say not to do this. They suggest squeezing it first onto a sugar cube, or not squeezing it at all (put a slice into the drink). If you say---it's because we squeeze lemons routinely now for their juice, so the rules are as for berries and pomegranates---is this really correct? Because lemon juice is still unique in that you can't/don't ever drink it straight, which is not true of juices in general. So please explain in as much detail as you have time for, how we came to be worried about squeezing lemons onto sugar cubes or into liquids. Also please explain the seemingly more lenient approach of the Aruch haShulchan in this matter. Thanks! Sincerely, Bob Miller
When the SHULCHAN ARUCH (OC 320:6) permits squeezing lemon-juice out of lemons, he permits squeezing the juice by itself (in order to drink it) without squeezing it into another liquid. This is because the normal manner was not to squeeze lemons for their juice, and thus doing so on Shabbos is permitted because it is not considered to be removing a liquid (the juice) from a solid (the fruit), since the juice is normally not used by itself as a liquid. This is the ruling of the majority of Rishonim, as cited by the BI'UR HALACHAH (320:1).
However, today it is the normal manner to squeeze just about all types of fruit for their juices (see Shemiras Shabbos k'Hilchasah, ch. 5, fn. 2), regardless of whether the juice is consumed straight (such as that of oranges) or whether the juice is consumed by adding water or sugar (such as that of lemons). The point is that the juice of the fruit is considered a significant entity in an of itself, apart from the rest of the fruit. Therefore, regarding the point you raise about the juice of lemons, since lemon-juice is very common today, even to drink as a beverage (with the additional of water and sugar), a lemon may not be squeezed on Shabbos, except onto a food.
The ARUCH HA'SHULCHAN writes regarding lemons that since it is not the normal manner to drink the juice, but only to use the juice to give taste to a food or to water, the juice is therefore not considered a separate entity from the fruit and it is permitted to squeeze it (even into a cup by itself). This is not the case today, when it is common to drink lemon-juice. It should be noted, also, that there is a difference between squeezing lemons into water in order to give taste to the water, in which case the water is the primary liquid and the lemon-juice is merely the taste-enhancer, and squeezing lemons to drink the juice with the addition of water, where the lemon-juice is the primary liquid and the water is added merely to dilute the lemon-juice. When the Aruch ha'Shulchan wrote that it is common to squeeze lemons into water, he was referring to the first case -- giving taste to water with the juice of a lemon. Today, however, it is even common to squeeze lemons in order to drink the juice, and even though the juice is normally diluted with water and sweetened with sugar, the primary liquid is the lemon-juice, and thus it is prohibited to squeeze lemons on Shabbos.
Y. Shaw