Blue raspberry flavor is a common flavoring for candy, snack foods, laffy taffy, sweet syrups and soft drinks. It is more commonly used in the United States, as a sweet flavoring. The flavor originates from Rubus leucodermis

Rubus leucodermis

Rubus leucodermis is a species of Rubus native to western North America, from British Columbia, Canada south to California, New Mexico and Mexico...

, more commonly known as the "Whitebark Raspberry" or "Blue Raspberry" for the blue-black color of its fruit.

Food products labeled as Blue Raspberry flavor often contain a bright blue food coloring, the most common being Brilliant Blue FCF

Brilliant Blue FCF

Brilliant Blue FCF , also known under commercial names, is a colorant for foods and other substances to induce a color change. It is denoted by E number E133 and has a color index of 42090. It has the appearance of a reddish-blue powder...

(although this coloring is not accurate to the real-life color of the fruit).