Beauty may not be skin deep, but when it comes to fruits and vegetables, skin is good. There lies a medicine chest of antioxidants, vitamins, fibre, phytonutrients and minerals.
An apple's bright exterior may attract the eye and protect the flesh inside, but it's more than just packaging. It contains quercetin, a fabulous flavonoid that's great for the heart and hard on allergies and that douses the fire of inflammation.
Okay, the health rhetoric is a bit overheated these days, and it's hard to know what's hype and what's not. But from all I've heard, it's foolish to peel and discard the skin of produce unless there's a reason. Pesticide residue would be one, unless you buy organic or grow your own. I admit that I peel apples when making a pie, for a nicer texture, but with baked apples, I owe it to my body to eat them skin and all.
Fruit skins vary in their appeal. Plum skin can be bitter, but the ripe flesh makes up for that. Kumquats are tart inside, but their thin, tender skin is sugar-sweet. Citrus peels are cooked and made into a sweetened marmalade, or turned into thin strips with a zester to season a variety of dishes: lemon zest in a creamy pasta sauce, for example, or orange zest in a daube (a beefy French stew). After eating an orange for dessert, I often nibble the rind, dipped in turbinado sugar.
Supposedly, the peel of a black, overripe banana is edible and nutritious, and I'd eat one if forced. Apparently, it contains an antidepressant, so maybe that would cheer me up.
Most vegetable skin is fine if scrubbed clean with a stiff brush. There's no reason to discard potato skins except that they won't go through the holes in a ricer, and even then you can add them back in. Why throw out a food item that is sold by itself as a side dish, topped with bacon, sour cream and cheese?
Parsnips and carrots need peeling only if unusually grimy or scarred. Turnips and rutabagas need no peeling if they're young. Beets I do peel if used raw. But cooking softens the skin, so it can usually be left on, though it tends to slip off of its own accord.
We take for granted that snap beans and edible-pod peas are eaten skin and all, though the pods of both are discarded after the seeds fully mature. Beans at the in-between stage, when the seeds are formed but not yet hard, vary as to type. Italian Romano beans have pods that often can be cooked to a wonderful tenderness. An heirloom variety named Garden of Eden can be eaten whole even when a foot long. Many cucumber varieties can be eaten unpeeled, too.
The skin of chile peppers is sometimes bitter, which may be why they're often roasted over coals and placed in a paper bag to steam, for easy skin removal. People sometimes slit corn kernels and press out the creamy pulp to avoid eating the presumably indigestible skin. But I'm for fibre, and the skin is often where the best fibre lies. Eggplant? It has delicious skin, and I would relish its chewiness even if it weren't a source of the antioxidant nasunin. And until I go for a Ph.D in vegetable chemistry, that's reason enough for me.