I’ve written extensively about the skin or “periderm” of the potato tuber over the years. You’ve learned how it develops, how it matures or “sets,” and the important role it plays in protecting the tuber from mechanical damage, water loss, and pathogen invasion.
In this column, I thought I’d examine its nutritional value, a completely different aspect of this important structure. To put it another way: Is the skin of the potato good for us to eat, and what does it “bring to the table?”
Having A Thin Skin
Potato skin comes in as many varieties as there are, well, potato varieties. The skin of the russet varieties favored for baking tend to be on the thick side and have a somewhat robust, chewy texture as well as a distinctive flavor.
On the other hand, many of the varieties used for boiling or in salads have much thinner skins with milder flavor and a more delicate texture. I think we all would agree that the wispy, practically nonexistent skins of new potatoes are part of their charm.
The skins of all varieties are edible, but appearance and periderm health both play an important role in whether people will want to eat them or not. As I mentioned earlier, potato periderm is a target for a number of pathogens , such as silver scurf, Rhizoctonia, and others, that can make it appear less than palatable.
Mechanical damage such as nicks, cuts, and abrasions also detract from the appearance. For growers hoping to target customers who desire to eat the potato skin, these problems are best avoided.
Whole potatoes provide excellent nutrition, with significant levels of potassium, iron, vitamins B and C, protein, and fiber. So exactly where are these nutrients located: in the skin or in the flesh of the tuber? The answer is that both contribute some level of these important nutrients, but the percentages contributed by each, as you might expect, are different depending on what nutrient you’re interested in.
Location Of Nutrients
One myth we should dispense with right off is that all of the nutrients of the potato are contained in the skin. In truth, the skin contributes more of some nutrients than the flesh does, but the reverse also is true.
Iron content is much higher in the skin than in the flesh with the skin contributing 80% or more of this nutrient. The protein content of flesh and skin is even, about 50/50. On the other hand, the skin contributes only about one-third of the fiber content while the flesh has 60% to 70% of the potassium and vitamins B and C.
You’d be right if you came to the conclusion that you’re denying yourself some important nutrients if you don’t eat the skin, but there’s even more to the story. An ensemble of biologically active compounds called “antioxidants,” which are believed to provide significant health benefits, are available from potatoes.
All of us are familiar with vitamin C, but other antioxidants include anthocyanins, carotenoids, phenols, and flavonoids. These compounds are reported to reduce cellular aging, cellular death, and could possibly even fight cancer.
Work to date on antioxidants has focused more on total tuber content and the skin/flesh ratios haven’t been well studied. All of the potato varieties examined so far contain significant amounts of these compounds, but some of those with heavily pigmented skins and/or flesh can provide very high levels of antioxidants. Research continues.
To skin or not to skin? Unless the skin has an obvious problem, there wouldn’t appear to be any reason not to eat it. This dietary and gustatory decision will obviously remain a personal choice but, as for me, I’ll be cheerfully eating the skins from here on out.