METHOD OF PREPARING BLACK COLORANT OF NATURAL ORIGIN Russian patent published in 2000 - IPC

FIELD: food and pharmaceutical industries. SUBSTANCE: green walnut or peel thereof is finely divided to particle size of not greater than 0.2 mm. The resulting compound is pressed to produce juice and the latter is dried to residual moisture content of 3-5 wt, dry oil cake is ground in vortex mill to powder with particle size of greater than 60 mcm. Powder is mixed with the resulting juice of walnut at ratio of not greater than 3.5:1, heated and maintained at 100-120 C till gel-like compound is formed, and the latter is cooled to room temperature, mixed with alcohol at ratio of not greater than 3.5:1, heated and maintained at 100-120 C till gel- like compound is formed, and the latter is cooled to room temperature, mixed with alcohol at ratio of at least 10: 1, mixture is maintained for at least 60 minutes and is subjected to filtration on electric filter. Compound deposited on electric filter is collected and centrifuged at rate of 5000 rpm for at least 30 minutes. Deposit from centrifuge is first heat treated at 150 C for 10-15 minutes and thereafter is thermally treated in muffle furnace at temperature of not higher than 350 C for 5-10 minutes. The resulting product is mixed with alcohol at ratio of not more than 10:1 maintained for 20-30 minutes and filtered to produce deposit on filter and which is final colorant concentrate. Method makes it possible to prepare ecologically pure black colorant from natural vegetable material having higher coloring properties. EFFECT: more efficient preparation method. 2 ex, 1 tbl