Ask Extension Database, NDSU Extension Service Ask Extension for answers to commonly asked questions. This discoloration can happen in canned apples, cauliflower, pears, peaches or beets. Keep all fruits and vegetables cool after you harvest them and before you can them. For hot-pack canning, do not overcook or heat at too high a temperature. Excessive heat alters virtually all natural food pigments.
Purple cauliflower is safe to eat.
Some cauliflower varieties have a genetic propensity to having a higher concentration of red, purple, or blue pigments. This is the same harmless, water soluble pigment found in eggplant, red cabbage, berries, plums and grapes. In other types of cauliflower the colorless or white pigments will predominate. Purpling can develop in white varieties of cauliflower if the heads are exposed to light while developing. Usually, the leaves are tied over the heads.