1. Soak the black rice in white vinegar. If it turns red after a few minutes (similar to the color of red wine, which is the result of anthocyanin reacting with acid), it is good rice. For artificially dyed rice, the color of the dye will appear immediately.
2. Take a small amount of black rice, breathe on it with hot breath, and then immediately smell it. High-quality black rice should have a normal, fresh aroma without any other odors. If it has an abnormal odor such as a slight strange smell, a musty smell, a sour smell, or a rotten smell, it is low-quality black rice.
3. Take a small amount of black rice, chew it slowly, or grind it and taste it. High-quality black rice has a good taste, is slightly sweet, and has no sour, bitter, or other undesirable flavors.
4. Scrape off the outer bran layer of the rice grains. If the inside of the grain is not white, it may have been artificially dyed. The black color of high-quality black rice is concentrated in the bran layer, the endosperm is still white and shiny, the grains are uniform, there are few broken grains, there are no insects, and it contains no impurities.