It seems I got me thinking ...
When boiling potatoes in water or a steamer, what, if any, is the effect of peeling the potatoes before vs. after the cooking process?
Does it matter at all whether they are peeled before or after?
I almost never peel potatoes. I like the flavor and texture of the skins, even in mashed potatoes, and unpeeled potatoes are less prone to becoming waterlogged.
According to Tablespoon.com, the Idaho Potato Commission recommends that you leave potatoes unpeeled for boiling for reasons of flavor and texture, even if you intend to peel the potatoes after boiling.
I like both, but they do taste differently, and "ash" quality pretty much fits what I feel on the tongue. Also, maybe it's my imagination, but I think unpeeled ones are bit more acidic, I prefer unpeeled for red meat and dishes with strong taste, and peeled to go with chicken, sweet meats etc. But here your mileage may vary. Some people can't tell difference, some can always tell, and some - only sometimes.
According to these datasheets:
Per 100g serving potatoes boiled with skin provide 22% of vitamin c, and without - only 12%. Given it's water soluble, I think it's safe to assume that even if you discard peel, you still get more C if you boil with skin. Other differences are small. Largest are fluoride and ash. Even if the nutritional meaning of ash is a bit different, it really fits to what I taste. And vitamin C is acid - again, fits with how I can describe taste differences. Maybe that's just a coincidence, maybe not, can't really tell.
Yes, there is a difference in taste. I can't tell you what causes it, possibly the skin preventing the water from properly penetrating the potatoes. But when I eat a peeled boiled potato, I can always tell if it has been boiled skin on or off.
My personal preference is very much for boiled-skin-off. Boiled-skin-on potatoes have their own specific taste even after peeling, which is slightly bitter and has a slight physical reaction on the tongue - not exactly hot, not exactly astringent, but somewhat reminiscent of both.
This is a taste I get when eating the potatoes as they are. Mashed, or swimming in some dip, the difference is too slight to notice.
When cooking potatoes with the skins on, the startch stays inside the potatoes instead of dissolving into the water. Makes the potatoes taste different (better in my opinion) and more beneficial for you. Tip: After they are cooked, it's easier and quicker to peel the skins of, just run them under cold water while peeling so you don't burn yourself!
Leaving the skin on can make them more difficult to mash or whip later without over working the potato. Over mixing it whipping too vigoursly will result in a glue like consistency. I still mash both peeled and unpeeled depending on the dish it is being accompanied with. When using a ricer the skins often get caught in the mesh and do not make it through. You can just scrape them off the bottom and chop them by hand but it will take more time. It is generally faster to peel them first (even though it won't seem like it) if you need them on the fly.
