The melacha of grinding includes all milling and grinding related activities. Generally speaking, one is not permitted to break down an object or substance to form smaller particles that will take on a new function.

One may therefore not grind coffee, pepper or rock salt. One must also refrain from crushing substances in a mortar. The rules apply to non-food substances, like in the case of making wood or metal shavings, as well as food.

With food, the rule applies to food items that originate from the ground as well as items that do not originate from the ground, but must be ground to be eaten. An example of this would be making baby food.

The toldot includes chopping raw vegetable into small pieces

The prohibition does not extend to substances that have already been crushed such as crumbling bread or chocolate. Likewise one may cut pieces of food, into pieced larger than is customary, right before the meal.

Additionally if one changes the manner of the ‘grinding’ in two dramatic ways it may be permitted.

When it comes to mashing substances like bananas, a potato or avocado, authorities are split. One should check with their rabbinic authority.

In the cases of medicine, one may not crush medicine unless it is needed to save a life as this would take precedence over the melacha.

_{(Issue March 2008)}