Peanuts are salted inside the shell by soaking them in brine, then drying them by roasting, leaving a salt residue behind on the nut in the shell. Sometimes a vacuum is used to remove air from the batch before the brine is introduced.
Peanuts are often salted inside the shell to improve their flavor. To salt peanuts while they are still inside the shell, whole peanuts are put into a sealed, pressurized tank that is filled with salt water.
The pressure in the tank forces the salty water inside the porous shells, salting the peanuts. The salted peanuts are dried and then roasted to bring their rich, nutty flavor. Roasting dramatically changes the peanut composition.
Raw peanuts are pea like in flavor until they are roasted. In fact, peanuts are not actually nuts. They are the seeds of a plant closely related to peas-hence the name, peanut.
What is peanut shell made of? The shell of a peanut is primarily cellulose. To put that in perspective, so are hay, leaves, twigs, lumber, cardboard, tree bark, sponges, the little see-through windows in recyclable envelopes. Cellulose is a great source of food energy, but that energy is very hard to release.
Eating peanut shells may provide fiber, but they can also interfere with normal digestive function. Peanut shells can accumulate in the gastrointestinal tract. Often, the buildup of foreign matter causes stomach distress and creates a mass that cannot pass through the intestines.
Content for this question contributed by Scott Takac, resident of North Olmsted, Cuyahoga County, Ohio, USA