THE RIPENING OF CHEESE. 239 



genous body similar to caseo-glutin, of which more is not known, there is 

 found a body which stands in its properties between albuminoids and 

 peptones ; further, leucin, combined with amido acids in comparatively large 

 quantity, as well as tyrosin and phenol-amido proprionic acids the last 

 two in smaller amounts and, finally, ammonia, but in very small quan- 

 tities, are all developed. Of ammonium magnesium phosphate, lactic acid, 

 butyric acid, and peptones, ripening cheeses contain only small quantities. 

 Only Facherin and Bellelay cheeses have been found comparatively rich in 

 peptones. The loss of their substance which the ripening cheeses suffer is 

 only very slight. That the older the cheeses become the greater are the 

 amounts of the albumin decomposition products, was shown by the advance 

 made in the ripening processes with the lapse of time. Milk-sugar is not 

 present in ripe cheeses, nor are xanthin bodies found in them. A separa- 

 tion of fat only takes place in very small quantities, and the increase of the 

 percentage of tri-glycerides in the cheese is not noticeable. Whether free 

 non-volatile fatty acids are present in cheeses could not be decided. It is 

 not impossible that the different caseo-glutins, which do not perfectly 

 agree with one another in their physical behaviour, are present in the 

 different ripe cheeses, and it appears very probable, from this fact, that 

 nuclein is gradually decomposed in the ripening process. In ripe Emmen- 

 thaler cheeses, on an average, about 80 per cent of the entire amount of 

 nitrogen belong to bodies of an albuminoid nature, and 20 per cent to 

 products of the decomposition of albumin. In skim-milk cheese, prepared 

 after the manner of Emmenthaler cheese, the changes taking place in the 

 material of the cheese in the ripening process are not exactly the same as 

 those taking place in the fat cheese. The watery extract is richer in 

 albumin, and poorer in albumin decomposition products. The latter also 

 shows a higher percentage of nitrogen than the fat cheeses. The extract 

 of skim-milk cheeses leaves behind, when strained, a very unpleasant- 

 smelling residue. 



The above-mentioned researches chiefly concern themselves with 

 the chemistry of ripening. On the other hand, the researches of 

 Cohn, Benecke, and Duclaux deal chiefly with the study of the 

 ferments concerned in the ripening of the cheese, and are bacterio- 

 logical in their nature. Duclaux describes a number of enzymes 

 which are separated by bacteria, and which co-operate with them in 

 the ripening of cheese. The bacteriological experiments which have 

 been carried out on the ripening of cheese have partaken of the 

 character of preliminary experiments only. They have merely 

 dealt with the surface of the subject, and have not been at all 

 exhaustive. Nevertheless, they have been very serviceable in 



