Boiling potatoes in their skins

A recipe from cooking-ez.com

Times:

Preparation	Cooking	Start to finish
20 min.	10 min.	30 min.

Step by step recipe

1	4 potatoes, of 2 different varieties (roseval and bintje here), will be used for a thorough test.
2	One of each kind is peeled.
3	All 4 are washed and dried, then weighed precisely and the weights noted.
4	The potatoes are all boiled in water.
5	When cooked, the potatoes are removed from the water, dried and weighed again. Result: no change in weight. Conclusion "You should not peel potatoes before boiling": false, peeled or not they behave the same.
6	Next the potatoes are left to cool in their cooking water until cold, then dried and weighed again. Result: the weight of the peeled potatoes has increased by 4 grammes each. Conclusion "You should not leave potatoes to cool in the cooking water": it's true if they are peeled, otherwise they will absorb some of the water.

Remarks

Both true and false: It's not necessary to leave the skins on potatoes for boiling, peeled or unpeeled they do not absorb water during cooking.
But you should not leave peeled potatoes to cool in the cooking water, because they will absorb water (about 7% in these tests). On the other hand, this "sponge" property of peeled potatoes might be an advantage when cooking them in something other than water, milk or cream for example, as they will absorb some of the good flavour.

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