| 摘要 |
A method of making dry edible non-toxic color lakes approved for food and drug use and of submicron particle size, comprising the steps of dissolving sodium bicarbonate in water at a temperature not higher than 13.degree.C., stirring aluminum chloride slowly into the cold sodium bicarbonate solution for about two hours, precipitating alumina hydrate, stirring the precipitated alumina hydrate for an additional half hour to insure the completion of the reaction, dissolving a dye in water, stirring the dye solution into the alumina hydrate slurry, adding a thin stream of aluminum chloride to the alumina hydrate slurry with stirring until the pH of the slurry reaches between about 4.1 to 4.3 to effect laking, continuing the slow stirring until the water-soluble dye has been completely absorbed onto the alumina hydrate, filtering the slurry in a filter press to form a filter cake, washing the filter cake with water to reduce the sodium chloride content thereof, drying the filter cake at 50.degree.C. to produce a dry cake of agglomerated lake particles, and grinding the cake of agglomerated lake particles into lake particles of average size of 1 micron, with the majority of particles being submicron in size. |
