552 



MANUAL OF MILK PRODUCTS 



"ropy or stringy" milk. These conditions 

 are the result of changes brought about by 

 the growth of different species of bacteria. 

 The occurrence of the bitter fermenta- 

 tion is more common in the case of market 

 cream than in milk. This group of bacteria 

 gain entrance to the milk at the time of 

 production and are able to grow at the ordi- 

 nary low temperatures at which cream is 

 held. Cleanliness at the seat of produc- 

 tion, and thorough sterilizing of all utensils, 

 will usually get rid of this trouble. 



The occurrence of ropy or stringy milk 

 sometimes causes serious trouble for the 

 milk-dealer. It is caused by the growth of 

 certain kinds of bacteria which produce a 

 slimy, viscid condition in the milk so that 

 it may be drawn out in fine strings or 

 threads. While ropy milk is not, so far as known, injurious to 

 health, its occurrence in market milk may result in serious 

 financial loss, because cus- 

 tomers do not like its ap- 

 pearance. Outbreaks of 

 this trouble usually occur 

 during cool weather, because 

 the bacteria of this group 

 grow best at low tempera- 

 tures. It is supposed that 

 their normal habitat is water, 

 and that they get into milk 

 through the water used for 

 rinsing the utensils, or by 

 the cows wading in a stream infected with this organism, the 

 bacteria then falling into the milk from the cow's body at 



Fig. 89. — Ropy or 

 stringy milk. 



Fig. 90. — Cheese made from gasy 

 milk, showing the gas holes. 



