TYPES OF I'.ACTERIA FOUND IN MILK 



49 



was traced to a yeast which had made its way into the dairy 

 supplying the factory, and which was producing the mischief. 1 

 (Fig. 26.) This bitter yeast was found on the leaves of trees 

 under which the open cans of milk were allowed to stand. In 

 all such cases the only remedy is, to trace the trouble to its 

 source, so as to be able to prevent a recurrence of the 

 trouble, and then to clean thoroughly the udders of the cows 

 and disinfect all milking utensils cans, vats, etc. 3. The 

 third type of bitter milk 

 is of less importance to 

 the dairyman. It occurs 

 in milk which has been 

 subjected to heat for the 

 purpose of sterilizing it. 

 Such action destroys most 

 of the bacteria present, 

 but sometimes leaves alive 

 some of the spore-bearing FIG 20 \I^ RULA AMARIj PRODUCING BIT- 

 organisms. When such TER MILK AND CHEESE (HARRISON) 

 milk is kept for some days, 



although it will not sour and usually will not curdle, it does 

 undergo other changes, and frequenty becomes bitter. The 

 bitterness may increase in strength with each day, making the 

 milk very unpleasant to the taste. Inasmuch, however, as the 

 use of sterilization is not a common process in dairying, and 

 sterilized milk is rarely kept for any length of time, this type of 

 bitter milk is of very little significance. There have been in- 

 stances where factories that put up a sterile milk have experi- 

 enced considerable loss from the development of bitter or- 

 ganisms in their product. Their only remedy is found in more 

 complete sterilization, by applying higher heat, which will kill 

 all spores. 



Alcoholic Fermentation. Although some forms of sugar 



1 Harrison. Ontario Agr. Coll., 120, 1902. 



