The first is to look at the surface: authentic black beans, black beans have uneven particle size, large and small, and the color is not all black, some are dark black, and some are black with red; The dyed fake black beans are basically the same size and the color is basically black.
The second identification method: you can take a proper amount of black beans and put them in a container, pour a proper amount of white vinegar, and then stir. After stirring, the white vinegar turns red, which is true black beans, but the white vinegar basically does not react, and the fake black beans do not change color.