Most of the time when I purchase blue potatoes they have blue flesh. However, once in a while I get some that have a creamy golden flesh. Looking at them I had no idea they would be different.
I know there are many varieties but usually in the grocery store we are not provided that information. I've tried asking the produce clerks but essentially they are stockers with very little knowledge about produce.
Is there a way you can tell without opening a bag or damaging a potato to get a look?
It's almost impossible to tell without studying all the different types of blue/purple potatoes and memorizing slight differences in size and hue. One trick is that the potatoes with the deepest, darkest blue skin typically have purple flesh. And the lighter ones are more likely to have flesh that's yellow or even white.
Sometimes, the potato will have a sign with the exact name of their variety:
Examples:
(I suggest doing a Google Image search on these varieties to learn the difference)
One interesting fact: the Andirondack Blue Potato is a hybrid developed by Cornell University, which is how it got its purple flesh. I'm not sure if purple-fleshed potatoes exist in nature.
