FOOD-COLOEIISrG SUBSTANCES. 5 



Candies, sirups, and other sugar products may be taken up directly 

 with hot water. 



Wines, liquoi-s, and other alcoholic beverages may be fii"st 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 reduc^^ 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. 



Sohd materials, such as fruits, flesh foods, etc., may be extracted 

 first with 80 per c^nt alcohol, containing a very httle acetic acid, to 

 remove basic dyes, cochineal, etc., sensitive to alkahes. 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 c[uite general in its applica- 

 bihty. However, with products colored with metaUic 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 sohd 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. 



"\^Tieat and rye products off(>r some difficult}- in the extraction with 

 dilute alcohol because of the solubility of th(^ plant prot(nns, gliadin 

 and hordein. In the case of macaroni, spaghetti, etc., boil the 

 anmTKMiiacal alcoholic extract containing the coloring matter until 

 most but not (juite all (jf the alcohol is removed. If th(^ 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- 

 clJoric acid and is poured into a hxrgo. scparato7-y funnel. Amyl alco- 

 hol ('(jUiil to about two-thij"ds of 1 lie original volume of the solution is 

 uddf-d and sufficient salt solution lo make the mixture s(!parate well. 



