CHAPTER XV. 



THE ANALYSIS OF CHEESE. 



A COMPLETE analysis of cheese includes determinations of the 

 water, fat, ash, salt, proteins, primary products of ripening (as 

 albumoses and peptones), secondary products of ripening (such as 

 amino-compounds, ammonia, and nitrates), and lactic and fatty 

 acids ; also, when present, milk-sugar. Few, however, of these 

 determinations can be made with accuracy, though results which 

 are of great utility can be obtained readily. In addition to the 

 determinations mentioned, the fat may be examined as to its 

 genuineness, and the proteins as to their digestibility. 



The earlier method of cheese analysis consisted of the esti- 

 mation of water, by drying at 100 C. (212 F.) to constant 

 weight ; of fat, by extracting with ether ; of ash, by ignition ; 

 and of casein, by difference ; this method has the advantage of 

 simplicity, but gives no information as to the changes that have 

 taken place during ripening. 



The following method will give fair results, and is easy of 

 execution : 



Richmond's Method Water, Fat, and Ash. Three to five 

 grammes of cheese are weighed into a wide platinum dish and 

 dried in the water-oven till the fat begins to run away from 

 the cheese. The basin is then turned up, so that the fat collects 

 at one side, and the drying continued for an hour or so. It 

 frequently happens that no fat runs away from the cheese ; in 

 this case the turning up of the basin may be dispensed with. 

 The basin is then removed from the oven, and treated several 

 times with ether to remove the fat. The ethereal solution is 

 collected in a flask, the ether evaporated, and the fat dried and 

 weighed. The basin and its contents are replaced in the water- 

 oven, and the residue dried to constant weight. The combined 

 weight of the fat and residue subtracted from the original weight 

 gives the water. It will be found that the removal of the fat 

 facilitates drying, but it is difficult to remove the whole of the 

 fat in this manner. The residue may now be incinerated at a 

 low red heat, and the ash weighed ; in this the salt may be 

 estimated by solution in water, and titration with silver nitrate 

 solution, using potassium chromate as indicator. 



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