CARMINE COLOUR (Cochineal)
Carmine or E120, is a pigment of a bright-redcolor obtained from the aluminium salt of carminic acid, which is produced by some scale insects, such as the cochineal scale and the Polish cochineal, and is used as a general term for a particularly deep-red color of the same name. Carmine is used in the manufacture of artificial flowers, paints, crimson ink, rouge, and other cosmetics, and is routinely added to food products such as yogurt and certain brands of juice, the most notable ones being those of the ruby-red variety.
To prepare carmine, the powdered scale insect bodies are boiled in ammonia or a sodium carbonate solution, the insoluble matter is removed by filtering, and alum is added to the clear salt solution of carminic acid to precipitate the red aluminium salt, called "carmine lake" or "crimson lake." Purity of color is ensured by the absence of iron. Stannous chloride, citric acid, borax, or gelatin may be added to regulate the formation of the precipitate. For shades of purple, lime is added to the alum; thus, the traditional crimson color is guaranteed not only by carminic acid but also by choice of its chelating metal salt ion.