Food coloring blue is either a synthetic colorant, like Brilliant Blue FCF (Blue 1), a triarylmethane dye, or a natural colorant, often derived from anthocyanins in red cabbage, which can turn blue with the addition of an alkaline ingredient like baking soda. Synthetic options are typically available as water-soluble blue powders and are used in products such as ice cream, drinks, and candies, while natural versions provide an alternative for products like creams and toppings.