In German, potatoes boiled in their jackets are called Pellkartoffeln whereas potatoes that are first peeled and then boiled in well-salted water are called Salzkartoffeln.
From Wikipedia (translation from German entry): “Pellkartoffeln are boiled or steamed potatoes that have not been peeled. ...
When potatoes are cooked in their skin, fewer vitamins and minerals are lost and more flavor is retained.
Pellkartoffeln are considered to be the simplest way to make this food staple and are also symbolic for a frugal (modest and down-to-earth) meal.”
“Normally, small or medium-size waxy or firm potatoes are used. They are cooked for 20 to 30 minutes (depending on size) or 10 minutes in a pressure cooker and then served hot. The potatoes are usually peeled directly on the plates after serving. To do this, you insert a fork into the potato so that you can hold it this way while peeling. It works best to use special forks that have three thin prongs in the shape of a triangle as the potato will fall apart easily if you use a normal fork. If you are using new potatoes or freshly harvested potatoes, you can also eat the peel. ... ”
“Pellkartoffeln can be used as the basis for other dishes such as potato salad, rösti, mashed potatoes, potato dumplings, and fried potatoes.
In Germany, Pellkartoffeln are usually served as a side dish. New potatoes are sometimes peeled first and then served immediately with asparagus and hollandaise sauce. Pellkartoffeln taste great dipped in quark, curry sauce, or simply in hot butter.”
“Alkaloids such as solanine and chaconine protect potatoes from predators. Potatoes that are damaged, sprouted, or have green spots contain higher levels of alkaloids and can be harmful to our health. Potatoes that have several green spots should not even be eaten after they are peeled.
Possible adverse health effects range from stomach and intestinal problems and sore throat to damage to the liver and central nervous system in severe cases. Since small children have a low body weight, they should not eat the peel.
Alkaloids form at very low or high temperatures. The optimal storage temperature is between four and six degrees Celsius in a dark place, for example, in a dark basement.
When potatoes are cooked in their jackets, the alkaloids are released into the cooking water. For this reason, you should not use the cooking water as an ingredient for another dish, but should instead simply throw it away.
According to the Federal Office of Consumer Protection and Food Safety (2005), one kilogram of potatoes contains between 20 to 30 mg of solanine and chaconine. An adult can safely consume 1 mg of alkaloids per kg of body weight. This means that 100 mg per kilogram of potatoes does not pose any risk to adults. Is is best to eat properly stored potatoes that arenʼt damaged or sprouted and that donʼt have any green spots and have been cooked in the peel.
The amount of alkaloids contained in potatoes is dependent on the season and type of potato. Of the potatoes tested, German potatoes had lower values than imported potatoes and fall potatoes had lower values than spring potatoes. The values have decreased over the last few decades.”