182 Defects of Milk. 



At the same time it appears as though the spoiling of milk, 

 for instance by souring, is less influenced by the temperature, 

 which of course may be of importance, than by the atmospheric 

 pressure. It could hardly be attributed to an accident that, ex- 

 cept at harvest time when the milking is sometimes hurriedly done, 

 the number of samples spoiled by souring were almost in recipro- 

 cal relation to the measured average value of the atmospheric! 

 pressure for the month. 



Likewise in several months a certain parallel exists between 

 the occurrence of dirty milk and souring, so that the dirt is present 

 in largest amounts during August, September, October and 

 November. 



Months in which milk contains a great deal of dirt appear 

 also to favor the requirements for the development of a putrid 

 taste. (Height in June, August and October, harvest time.) Dur- 

 ing this period the milk is not aired and cooled, so it " suffocates." 

 The cans are not cleaned, and all dairy work is slighted. 



Direct contamination with cow manure appears to be of less importance in the 

 development of an animal flavor, than pollution with bacteria from the skin of the 

 cow, which may contaminate the animal while in pasture. These views are strongly 

 supported by the experiments of Wolf and Weigmann, who proved the identity of the 

 bacterial flora of the defective milk with the bacteria which were cultivated from the 

 pasture plants, and by the experiments in which the authors succeeded in reproducing 

 artificially these defects by using special bacteria. 



This view is also supported by the observations of the author. A milk dealer 

 complained about the bad taste of milk in a certain delivery. It was noticed that only 

 the evening milk of the farm, and not the morning milk possessed the defect. Before 

 the evening milking the animals were kept in a pasture during the day. It was remarked 

 from the beginning that the morning milk did not have the taste, which was the more 

 suprising since the animals by standing in the stable during the night must have affected 

 the purity of the stable air. Nevertheless the evening milk which was obtained in the 

 stable after a sufficient airing and cleaning, possessed the objectionable taste. Of course 

 the time could have played a part since both the morning and evening milk were delivered 

 at the same time, the evening milk being allowed to stand all nisrht at a temperature of 

 12 deg. C. The milk was kept in a milk room next to the stable. 



The conditions, however, were not changed by removing the milk immediately after 

 milking, to a well-ventilated room, cooled by ice. 



The passing of the odoriferous substances into the milk directly from the food 

 could be excluded since the substances could then have been demonstrated in the morning 

 milk as well, and therefore the only explanation which remained was that while lying 

 down the abdomens of the animals became contaminated with the bacteria of pasture 

 plants (meadow grass and clover). These bacteria contaminated the evening milk during 

 milking in the stable, whereas the morning milk was principally contaminated with 

 bacteria from the bedding. All other factors could be given about equal consideration. 

 That the age of the milk did not play a part was proven by the fact that the morning milk 

 in spite of longer keeping during both cold and warm weather in exposed or covered 

 vessels, had never been affected by the disagreeable taste. 



It is almost impossible at the present time to establish definite 

 relations between defects in milk and contamination of milk with 

 bacteria, since the propagation of the bacteria causing the defects 

 may be influenced by the most varied factors. 



It should be especially emphasized that bacteria of one and 

 the same species may under certain conditions produce different 

 defects in milk, depending on the accompanying conditions, as for 

 instance whether they are associated with one or several othei' 

 species of bacteria. 



