Bacteria in the Cheese Industry. 



153 



Where but little acid is developed as in a sweet curd 

 cheese the texture is open and porous. The numerous 

 cavities that are to be noted arise from the fact that the 

 curd particles have not been closely matted together. 

 This matting or cementing of the curd masses is due to 

 their partial solution under the liquefying influence of 

 the acid produced by the bacteria. Where these "me- 

 chanical holes" are present, gas is almost invari- 

 ably developed, as the gas-producing bacteria that are 

 quite susceptible to acid are not inhibited under these 

 conditions. This gas finds its way into the ready-made 

 mechanical holes, greatly distending them as in fig. 33. 



FIG. 33. Showing " mechanical holes " in a sweet curd cheese and the disten- 

 tion of the same by gas. 



L shows appearance of a sweet curd cheese immediately after it is taken from 

 the press. The " mechanical holes " are produced by the failure of the curd par- 

 ticles to cement, owing to the absence of acid. 



P shows appearance of a duplicate cheese four days after removal from press. 

 The gas produced by bacterial germs fills up and distends these " mechanical 

 holes," thus causing a marked distortion in shape of cheese (huffing). 



161. Physical changes in ripening. When a green 

 cheese is taken from the press, the curd is tough, firm, 

 but elastic. It has no value as a food product for imme- 



