Chapter VII 

 Defects of Cheese 



FROM the scientific point of view, the defects of cheese must be 

 classified according to their origin. They may be due to milk of 

 abnormal composition, faulty treatment in the manufacture (including 

 production and treatment of the curd, pressing, salting, and treat- 

 merit during ripening) or to bacterial action. Only the last- 

 mentioned cause comes within the scope of this work. In practice, 

 however, the various causes are so interdependent that it is 

 difficult to make any hard and fast distinction. By judicious 

 treatment of the milk and the cheese, it will generally be possible 

 to avoid the development of harmful organisms, whereas with 

 careless treatment, even when starting with good milk, their 

 development may easily be encouraged. 



To take an instance, if the milk has curdled badly (a fault 

 which might have been corrected by raising its temperature or 

 adding a little calcium chloride), owing to the presence of raw 

 milk or milk from cows which are getting towards the end of their 

 lactation period, the curd will not dry readily and the cheese will 

 tend to become spongy, even though the milk used could be described 

 as good from the bacteriological point of view. Sponginess may 

 thus be due, not merely to the presence of large numbers of gas- 

 producing organisms, but to an excess of lactose in the curd. 

 As has been mentioned, gas-producing organisms may come from 

 the udder (Aerogenes mastitis), though in the great majority of 

 cases they owe their presence to diarrhoea among the cows and 

 unclean milking ; the acuter the digestive trouble, the richer 

 will the manure be in gas-producing bacteria and the greater 

 will be the difficulty in keeping the milk free from infection through 

 the manure. The gases which are formed consist chiefly of 

 hydrogen and carbon dioxide, the former being the more objection- 

 able, for the water in the cheese will absorb large amounts of 

 carbon dioxide before the slightest tendency towards sponginess 

 becomes apparent. At 15 C. and at atmospheric pressure water 

 will absorb its own volume of carbon dioxide, at two atmospheres 

 pressure twice, and at three atmospheres three times its volume, 



