Answer from Dr. Art Hill, University of Guelph:
Who says there are no blue foods? Skimmed milk is blue; you can see that if put it against a white background. And, the food item in the photo attached is blue!
Answer from Dr. Farah Hosseinian, Carleton University
We don't have an automatic appetite response to blue. Pure blue is a rare pigment in nature. Most forms of blue are either a form of purple, or blue-green. The same is true with blue corn and blue potatoes. They're purple. Even blueberry is not blue!! To make pure blue food, usually artificial colours are required (e.g. bubble gum).
Answer from Dr. Apollinaire Tsopmo, Carleton University
Natural blue foods are not common. One of the reasons is their low quantity in many foods compared to other pigments. Green, red and yellow pigments are often present in large quantities. Although there are artificial blue colours permitted as food additives, they are often used in combination with yellow to give green or with other colours for brown or black appearances.« RETURN TO THE QUESTIONS