Sorghum red is obtained by extracting the exocarp (husk) of black-purple or red-brown sorghum seeds with hot water or acidic aqueous ethanol, or extracting with warm alkaline aqueous solution and then neutralizing, then concentrating and drying. Brown pigment. Sorghum red is stable to light and heat.
The aqueous solution of sorghum red is reddish brown, light in color when it is acidic, and dark when it is alkaline. It forms complex salts with metal ions, but as long as a small amount of sodium pyrophosphate is added, the influence of metal ions can be suppressed.