On Yom Tob, unlike Shabbat, activities that involve "Ochel Nefesh" – food preparation – are permissible. Thus, one may cook food on Yom Tob. The question arises as to whether this applies also to squeezing fruit. On Shabbat, squeezing fruits – known as "Sehita" – is forbidden, as this constitutes a Tolada (subsidiary) of the Shabbat prohibition of "Dash" (threshing). (Squeezing gapes and olives for their juice on Shabbat constitutes a Torah violation, whereas squeezing other fruits is forbidden by force of Rabbinic enactment.) Does this apply on Yom Tob, as well? If a person wishes to prepare freshly squeezed orange juice on Yom Tob, for example, may he squeeze oranges for this purpose, just as he may cook and make other food preparations, or is this forbidden?
The Shulhan Aruch (Orah Haim 495:2) rules explicitly that squeezing fruits is forbidden on Yom Tob just as it is on Shabbat. This applies to all fruits, including apples, oranges and grapefruits. Even though squeezing fruit involves food preparation, it is forbidden on Yom Tob just like on Shabbat. This is the accepted Halacha, as ruled by the Ben Ish Hai (Rav Yosef Haim of Baghdad, 1833-1909), in Parashat Yitro, and Hacham Ovadia Yosef, in Yabia Omer (vol. 8). There are authorities who ruled leniently on this issue, such as the Be’er Moshe (Rabbi Moshe Stern of Debereczyn), who distinguished between ordinary squeezing and using a juicer. When one makes juice with a juicer, he claims, the juice is not separated from the fruit, as everything – the fruit and the juice – is crushed together and poured into the cup. Rav Shalom Mesas (Morocco-Israel, 1909-2003) also allows squeezing fruit on Yom Tob, in his work Shemesh U’magen (vol. 2, Siman 30). As mentioned, however, the accepted Halacha does not follow this view, and it is forbidden to squeeze fruits on Yom Tob, whether it is done manually or with a juicer.
Summary: Although food preparation is generally allowed on Yom Tob, it is forbidden to squeeze fruits on Yom Tob, whether by hand or with a juicer.