302 DETECTION OF ADUI/TERANTS AND PRESERVATIVES 



2. "DETECTION OF ANILIN ORANGE (IN THE CURD) 



"The curd of an uncolored milk is perfectly white after com- 

 plete extraction with ether, as is also that of a milk colored with 

 annatto. 



"If the extracted fat-free curd is distinctly dyed an orange or 

 yellowish color, anilin orange is indicated. To confirm the presence 

 of this color, treat a lump of the fat-free curd in a test tube with 

 a little strong hydrochloric acid. If the curd immediately turns pink, 

 the presence of anilin orange is assured. 



3. "DETECTION OF CARAMEL (IN THE CURD) 



"If the fat-free curd is colored a dull brown, caramel is to be 

 suspected. Shake a lump of the curd, as in (2), with strong hydro- 

 chloric acid in a test tube and heat gently. In the presence of cara- 

 mel the acid solution will gradually turn a deep blue, as will also 

 the white, fat-free curd of an uncolored milk, while the curd itself 

 does not change color- It is only when this blue coloration of the 

 acid occurs in connection with a brown colored curd, which itself 

 does not change color, that caramel is to be suspected, as distin- 

 guished from the pink coloration produced at once under similar 

 conditions by anilin orange." 



4. "LYTHGOE'S TEST FOR ANILIN ORANGE 



"Treat about 10 c.c. of the milk with an equal volume of hydro- 

 chloric acid (sp. gr. 1.20) in a porcelain casserole and give the dish 

 a slight rotary-motion. If an appreciable amount of anilin orange 

 is present, a pink color will at once be imparted to the curd particles 

 as they separate." 



Detection of Sucrose in Milk to Which Sucrate of Lime 1 (Visco- 

 gen) Has Been Added 



25 c.c. of milk or cream are shaken in a small Erlenmeyer flask 

 with 10 c.c. of a 5 per cent solution of uranium acetate, allowed to 

 stand for five minutes and filtered through a folded filter. If the 

 filtrate is not clear, pour through filter again until clear. To 10 c.c. 

 of the filtrate 2 c.c- of a cold saturated solution of ammonium 

 molybdate and 8 c.c. of hydrochloric acid (one part of 25 per cent 

 acid to seven parts of water) are added. The mixture is shaken 



1 Barthel, Milk and Dairy Products. 



