The keyword for this is "chromaphore", if you want to dig deeper. This will take you to molecular orbital theory, that is the description of the energetic states of electrons in molecules.

I would add an interesting chemistry tidbit that has to do with colors.

Different chemical bonds will absorb different wavelengths of electromagnetic energy depending on how stable they are. In organic chemistry, a lot of times that has to do with how much electrons are delocalized (or “have the freedom to move to different bond sites”) over large numbers of double bonds. If you look up the structure for carotene (the chemical that makes carrots orange), you’ll notice a ton of these alternating single and double bonds. The electronics are delocalized over that whole stretch. That pushes the absorbance to higher wavelength. A lot of molecules of colors have a high degree of stabilizing electron resonance like that. Tomatoes have even more conjugation so they absorb higher up into the red wavelength region. In general, all those are high wavelengths for chemical bonds to be absorbing, which is why it takes so much conjugation. More typical bonds with less conjugation will absorb down in the UV spectra or lower wavelengths.

Here’s a source that talks about some colors in food and their chemical structure. Oh it has blueberries too! That molecule looks super cool. :)

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