280 PRINCIPLES AND PRACTICE OF MILK HYGIENE 



the size of the curd. P 2 , increased amount of fluid, less 

 curd. P 3 , amount of fluid large in proportion to the size 

 of the curd. This type of curd is produced when a large 

 proportion of peptonizing bacteria are present in the 

 milk. When the number of bacteria is large, it is usually 

 an indication that the milk has been contaminated with 

 dust from hay, fodder or soil, or that a suppurative con- 

 dition is present in the herd. When milk is produced 

 under good conditions and is kept cool, the peptonizing 

 bacteria (udder cocci) will predominate but the total 

 number of bacteria will be small. 



3. Gaseous Curd. A white, jelly-like curd contain- 

 ing gas bubbles and, when gas has been formed in large 

 quantity, presenting a sponge-like appearance. More 

 or less fluid is present and this may also contain gas bub- 

 bles. Gi, a few gas bubbles in the cream layer or in the 

 curd. G 2 , gas bubbles numerous in the cream and curd ; 

 gas bubbles may also be present in the fluid. G 3 , curd 

 sponge-like, containing many gas bubbles ; may be split 

 and a portion driven to the top; gas bubbles in fluid. 

 The gaseous curd is produced when a large percentage 

 of gas-forming bacteria is present and is usually an in- 

 dication that the milk has been contaminated with an ex- 

 cessive amount of manure. It may also occur when pol- 

 luted water is used to wash the milk vessels and utensils. 



4. "Flaky" or Flocculent Curd. Curd in flakes or 

 flocculi, associated with a turbid fluid, which may be 

 whitish, yellowish, or otherwise discolored. Fli, curd in 

 fine flakes or partially homogeneous. F1 2 , large flakes 

 and considerable fluid. F1 3 , large flakes, torn, with white 

 or discolored fluid. This type of curd is produced when 

 saccharomyces which ferment lactose are present in large 

 numbers. The casein is permeated with fine gas bubbles 



