DAIRY PRODUCTS BUTTER. 37 



stirring. Gather the curd, when possible, into one mass by the stirring rod, and 

 pour off the whey. If the curd breaks up into small flecks, separate from the whey 

 by straining through a sieve or colander. Press the curd free from adhering liquid, 

 transfer to a small flask, and macerate for several hours (preferably over night) in 

 about 50 cc of ether, the flask being tightly corked and shaken at intervals. 



(1) Detection of annatto (in the etfier extract). 



Decant the ether extract into an evaporating dish, place on the water bath, and 

 evaporate off the ether. Make the fatty residue alkaline with sodium hydroxid, and 

 pour upon a very small wet filter while still warm. After the solution has passed 

 through, wash off the fat from the filter with a stream of water and dry the paper. 

 If, after drying, the paper is colored orange, the presence of annatto is indicated, 

 confirmed by applying a drop of stannous chlorid solution, which, in presence of 

 annatto, produces a characteristic pink on the orange-colored paper. 



(2) Detection of aniline orange (in the curd) . 



The curd of an uncolored milk should be perfectly white after complete extraction 

 with ether, as would also that of a rnilk colored with annatto. 



If the extracted fat-free curd is distinctly dyed an orange or yellowish color, 

 aniline 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 aniline 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 (b), with strong hydrochloric acid in a test tube and heat 

 gently. The acid solution of the caramel-colored curd will gradually turn a deep 

 blue, as would also the white, fat-free curd of an uncolored milk, while the curd 

 itself does not change color. a 



(b) LYTHGOE'S TEST FOR ANILINE ORANGE.** 



Treat about 10 cc of the milk with an equal volume of hydrochloric acid (sp. 

 gr. 1 . 20) in a porcelain casserole, and give the dish a slight rotary motion. Ir aniline 

 orange is present in appreciable amount a pink color will at once be imparted to the 

 curd particles as they separate out. 



(B) BUTTER. 

 1. GENERAL DISCUSSION. 



The most common adulteration of butter is the substitution of fat other than butter 

 fat. This is effected either by oleomargarine or by mixtures of oleomargarine and 

 butter. Within the last few years a new product, called process or renovate* 1 butter, 

 has been sold extensively as butter. The process of its manufacture is, briefly, as 

 follows: 



Poor and rancid butter is melted, the curd and brine are allowed to settle, the froth 

 and scum skimmed off, after which the clear fat is drawn off and completely aerated 

 so as to remove any unpleasant odors. Next, pure skimmed or whole milk is added 

 and the mixture is thoroughly stirred so as to form a complete emulsion, ami is 



It should be noted that it is only when this blue coloration of the acid occurs in connection with a 

 hroii'n-c(ifr<'(t curd, which itself does not change color, that caramel is to be suspected, a distin- 

 guished from the pink coloration produced at once under similar conditions by aniline on in, ire. It 

 is to be regretted that there are no such delinile confirmatory tesls for caramel as there are for 

 annatto and aniline orange. See I'.Mli An. Rep. Mass. Stute Board of Health (l.ssTi. p. l,s;i. 



'Jour. Am. Chem. Soc., I'.lOO, _'_', 81o. 



