Threshing, the av melachah of dosh, is forbidden on Shabbat. In the Mishkan, dosh was performed by treading or using a flail to beat produce in order to remove the seeds. As such, the av melachah of dosh refers to threshing using a utensil designed for that purpose, or treading on the produce.1

Essentially, dosh is the removal of foods or liquids from where they are encased.2 Although this would seem to include most fruits and vegetables that we peel, like bananas and oranges, that is not the case. The threshing in the Mishkan was done while the produce was still in the field. Most of our fruits and vegetables are peeled just before they are eaten, and would in fact be rotten if peeled so far in advance. Since the manner is incomparable, it is not included in the melachah. Moreover, the peels are directly attached and can be considered part of the fruit itself. Therefore, the removal of their peels is no different than cutting the fruit, which is obviously permitted.3 One should be careful not to use a peeler on Shabbat, however, and use a knife instead.4

Dosh in the Mishkan

Flour was needed for the lechem hapanim—the showbread which was baked on a weekly basis—and for some of the sacrifices. To produce the flour, the wheat needed to be threshed after it was harvested.5 Plants were also threshed to make dyes for parts of the Mishkan.6

Toladot

Mefarek, a common toladah of dosh,7 includes:

  1. Removing peas or beans from an inedible pod.8
  2. Milking a cow. Since the milk is held in the udder, drawing the milk out is considered dosh.9
  3. Crushing grapes for juice and olives for oil. The Torah gives seven liquids special status in Jewish law. Since wine and oil are part of the seven, the juices inside grapes and olives are not considered part of the fruit, but a separate entity contained within the fruit. Squeezing them out removes them from where they are contained and is included in dosh. Juice which seeps out of grapes or olives may also not be consumed, since it may bring one to actually crush the fruit to make more juice.10
  4. Wringing liquids out of clothing or material. If the liquid is clear, then wringing out the garment is forbidden under the melachah of melaben - laundering. If the liquid is not clear, one would only be liable for mefarek if the person wanted to use the liquid he or she is squeezing out. Practically, since most people don’t care for the liquids they squeeze out of their clothes, wringing out such a garment is a rabbinic prohibition.11

Rabbinic Enactments

Squeezing fruits: The sages were concerned that if people were allowed to squeeze fruit on Shabbat, they would fail to recognize the crucial difference between squeezing grapes and olives which is forbidden, and all other fruits which are permitted. As such, they forbade squeezing any fruits or vegetables which are commonly squeezed for their juices. Moreover, if juice seeps out from a fruit one intends to squeeze, it is forbidden to drink that juice on Shabbos, since that may lead one to actually squeeze the fruits to make more juice.12

Defrosting: Crushing ice to melt it, or defrosting something into a liquid, is also forbidden on Shabbat. When the frozen item becomes a liquid, a new substance has been created, which is forbidden on Shabbat under the prohibition of molid. Additionally, turning frozen substances into liquids is comparable to squeezing fruits for their juices, which - as mentioned - is forbidden. Putting ice into a drink, however, is allowed, because the melted ice is not noticeable as a separate entity.13

Common Activities to Avoid:

  1. Squeezing the towel or napkin when wiping up a spill.
  2. Squeezing lemon into a cup of tea.
  3. Using a sponge to wash dishes.14
  4. Taking out a bottle of milk to defrost.15