For food, it is impossible for natural biological pigments to exist sapphire blue. We think blueberries are blue because there is a layer of wax on the surface of blueberries, which looks blue when superimposed with the color of fruits. In fact, the real colors of blueberries are dark blue and purple.

Even if we don't require sapphire blue to appear in human food, even if the conditions are slightly relaxed, there will be few blue foods in human food, because there are too few natural blue biochemists, and blue generally implies that it is not delicious.

Most people like bright colors. When eating, no one will eat dark gray food, so human beings will naturally have an aversion to blue in the process of evolution. Studies have shown that blue will reduce people's appetite.

Extended data? Blueberries not only have the ecological benefits of carbon fixation and soil erosion prevention, but also have some special ecological benefits. The three kinds of blueberry varieties have their own characteristics and are suitable for planting in areas with different climatic conditions.

Moreover, blueberries are suitable for growing in acidic soil. Overacid soil is usually abandoned because it is not suitable for the growth of crops and trees, and blueberries just need such soil conditions, which can make many barren areas have a green again.