444 MICROBIOLOGY OF MILK AND MILK PRODUCTS 



DAIRY UTENSILS. All utensils which are to be used in connection 

 with milk should be so constructed that there are no cracks or crevices 

 in which the milk can accumulate and from which it is not easily 

 washed. A milk pail with an open seam may be the cause of serious 

 trouble in the dairy. The dairy utensils should be simple in construc- 

 tion, and so made that they can be thoroughly cleansed with ease 

 and made of such material that they can be thoroughly sterilized 

 either with water which is actually boiling or in steam. They should 

 then be thoroughly dried and kept so till again needed for use. When 

 moisture is left in cans and other utensils bacteria can grow rapidly 

 and be the means of serious contamination when fresh milk is poured 

 into them. 



THE MILKER. No food material requires greater care and cleanli- 

 ness on the part of those handling it than does milk. All persons having 

 to do with the handling of this delicate food product should constantly 

 keep in mind that clean hands and clothing and extreme cleanliness in 

 every operation is very necessary if milk of good quality is to be ob- 

 tained. 



GROUPS OR TYPES or MICROORGANISMS FOUND IN MILK AND THEIR 



SOURCES 



In studying the types of bacteria found in milk, it is convenient 

 to arrange them in groups based upon their action on the milk and 

 their effect upon persons consuming it. There are certain types of 

 organisms which are very troublesome to the milk dealer but which are 

 not injurious to the consumer. Other species which may be of little or 

 no significance from their action on the milk are of greatest significance 

 from the standpoint of the consumer since most of the disease organisms 

 which may be carried by milk have no appreciable action upon it. Still 

 other forms are of but little importance to either the dealer or the con- 

 sumer and others are troublesome to both. 



GENERAL SIGNIFICANCE OF ACID-FORMING BACTERIA. Of all the 

 bacteria that find their way into milk, those that are able to ferment the 

 milk sugar, producing from it different kinds and amounts of acids, find 

 more favorable conditions for growth at ordinary temperatures, 15 to 

 45, than do those belonging to other groups. Because of their greater 

 rapidity of growth and because of the inhibiting effect of their by-prod- 



