FOOD-COLOBING SUBSTANCES. 5 
Candies, sirups, and other sugar products may be taken up directly 
with hot water. 
Wines, liquors, and other alcoholic beverages may be first diluted 
and warmed on the water bath to remove alcohol. However, for the 
subsequent treatment with immiscible solvents it is not usually 
necessary that the alcohol be driven off as it is sufficient to dilute 
the sample to reduce the alcohol content to 10 per cent or less. This 
very often is preferable to heating the sample; but it must be borne 
in mind that the distribution of the coloring matters will be more or 
less modified by the alcohol. 
Solid materials, such as fruits, flesh foods, etc., may be extracted 
first with 80 per cent alcohol, containing a very little acetic acid, to 
remove basic dyes, cochineal, etc., sensitive to alkalies. The pulp 
separated from the acid alcohol solution may then be digested with 
dilute alcohol of from 65 to 80 per cent strength, containing from 
3 to 5 per cent of ammonia. If both extracts are colored it is easiest 
not to work them up separately, but to boil off the alcohol and am- 
monia from the second portion, and the alcohol from the first, and 
then combine them. This procedure is quite general in its applica- 
bility. However, with products colored with metallic lakes, such as 
those of the flavone and flavonol dyestuffs, the treatment with strong 
hydrochloric acid and amyl alcohol, suggested below, is perhaps more 
satisfactory. Lake pigments in many cases also can be washed off the 
surface of the food material, since they are most often used as facings. 
The washings are allowed to settle or are whirled in a centrifuge, and a 
portion of the sediment containing the lake is treated for identifica- 
tion of the color. Most lakes are decomposed , at least to a large 
extent, by hydrochloric acid and amyl alcohol. 
From many solid products such as jams and meat pulp the com- 
mon coloring matters, including the permitted dyes, can be extracted 
directly by adding concentrated hydrochloric acid and shaking 
thoroughly with amyl alcohol. The subsequent work is shortened 
and, with strongly colored materials especially, the plan is often 
quite satisfactory. 
Wheat and rye products offer some difficulty in the extraction with 
dilute alcohol because of the solubility of the plant proteins, gliadin 
and hordein. In the case of macaroni, spaghetti, etc., boil the 
ammoniacal alcoholic extract containing the coloring matter until 
most but not quite all of the alcohol is removed. If the hot residue 
is of a semisolid consistency, it is best to add a little alcohol. It is 
then treated with, about one-half of its volume of concentrated hydro- 
chloric acid and is poured into a large separatory funnel. Amyl alco- 
hol equal to about two-thirds of the original volume of the solution is 
added and sufficient salt solution to make the mixture separate well. 
