|MadSci Network: Botany|
No, blue corn is not due to iodine because the blue is in the outer aleurone layer, not throughout the starchy interior. I assume the color is an anthocyanin. Indian corn grains come in a wide variety of colors, and anthocyanins have a wide color range depending on the pH. A common school science activity uses an extract of red or purple cabbage leaves as a pH indicator.
The blue in blue potatoes is also an anthocyanin and usually occurs mainly in the periderm, the several layers of corky cells just below the epidermis, the outer layer. Periderm and epidermis comprise what is commonly called the potato skin. Some varieties also have some anthocyanin in the cortex, which is the starchy inner tissue.
Blue Corn Production and Marketing in New Mexico
Potato Association of America Handbook - INTRODUCTION
Re: Where do fruits and vegetables get their color?
Try the links in the MadSci Library for more information on Botany.