Cosmetic Raw Materials Curcumin CAS 458-37-7 Food Yellow Coloring Plant Extracts

An orange-yellow crystalline powder with a characteristic odor. Melting point: 179–182°C. It is insoluble in water and diethyl-ethe, but soluble in ethanol, glacial acetic acid, and propylene glycol. It turns reddish-brown under alkaline conditions and pale yellow under acidic conditions. It forms a yellow-red lake with magnesium hydroxide. It forms chelates with metal ions—particularly iron ions—resulting in discoloration; iron ion concentrations as low as approximately 5 mg/kg begin to affect the pigment, while levels exceeding 10 mg/kg cause it to turn reddish-brown and reduce its coloring power, necessitating the use of appropriate containers. It is best used in conjunction with chelating agents such as sodium hexametaphosphate or sodium acid pyrophosphate. It exhibits poor light and iron-ion stability but good heat stability. It possesses strong dyeing power (especially for proteins).