I had to buy them. A coworker and I visited a farmer's market on our lunch break, and there they sat quietly, piled up in a basket at the far end of the table. Purple potatoes.
They were smaller than the basic red-skinned potatoes I usually buy for roasting and smashing and all other forms of tatery goodness, and they weren't cheap, but they were purple. My inner seven-year-old squealed "purple!!!!" and I forked over the money.
Well, my friends, it turns out that unlike red potatoes, whose beauty is only skin deep, the vivid purple shade of this variety goes right to the core. I don't know what species I purchased; there are several varieties of blue and purple potatoes in existence, and the sign said, unhelpfully, "purple potatoes". If I return to the market, I will ask the farmer about their lineage.
Normally, in the nutrition world, brighter and deeper colors indicate healthier food (Cheez-its and Kool-Aid notwithstanding). So, what's with the purple? do they taste purple? Are these potatoes healthier than red potatoes or Russets, and should I keep shelling out more money for them?
As far as flavor goes, my experiment with roasted garlic purple potatoes resulted in... roasted garlic potatoes. With my eyes closed, I'm confident I would not have been able to tell the difference between a red or a purple potato prepared in the same way. And these looked so incredibly cool on my plate beside the chicken!
I did a little digging, and it turns out that the purple color is from high levels of anthocyanins, which is the same antioxidant that makes blueberries a "superfood". Proof once again that sometimes "ingredients you can't pronounce" and "chemicals" can be damn good things to have in your food.* In all honesty, the jury is still out on whether the antioxidants and other compounds in blueberries and other fruits actually make as big a difference in vivo (in your body) as opposed to just in the lab, but I see no reason not to add as many colorful foods to your diet as you can. My educated guess is that these potatoes are marginally better for me than the average white-fleshed potato, but not by a whole lot and probably not enough to justify the extra cost on a regular basis.
That said, I bought more. I plan on boiling and mashing them this time, because apparently anthocyanins are water soluble, and I want to see if the purple washes out with boiling. Science!
* I still find myself getting pissed off to an absurd degree when I hear natural-foods people railing against "chemicals". If you're against pesticides, or artificial coloring, or preservatives, say so. Oxygen is a chemical, for crying out loud - don't be dissing chemistry as a whole just because you don't understand it.