CONTENTS XIX 



DIVISION IV. MICROBIOLOGY OF MILK AND MILK PRODUCTS 



CHAPTER I. THE RELATION OF MICROORGANISMS TO MILK. (Stocking.) (The Acid- 

 forming Bacteria, by Hastings.) 428 



Character of milk. Absorbed taints and odors. Changes due to microorganisms. 

 Microbial content of milk, Common milk, special milks, certified milk. 

 Sources of microorganisms in milk, Interior of cow's udder (healthy udders, 

 diseased udders), exterior of cow's body, atmosphere of stable and milk house, the 

 milker, utensils, water supply. Methods of preventing contamination of milk, 

 Individual cows, care of the cow's body, avoid dust in atmosphere, dairy utensils, 

 the milker. Groups or types of microorganisms found in milk, and their sources, 

 General significance of acid-forming bacteria, groups of acid-forming bacteria (char- 

 acteristics of the Bad. lactis acidi group, characteristics of the B. coli-aerogenes 

 group, characteristics of the Bact. bulgaricus group, characteristics of the coccus 

 group) (Hastings), bacteria having no perceptible effect upon milk, the casein-di- 

 gesting or peptonizing bacteria, pathogenic organisms. Factors influencing the 

 developing of microorganisms in milk, Initial contamination, straining, aera- 

 tion, centrifugal separation, temperature, pasteurization, the use of chemicals. 

 The normal development of microorganisms in milk, Germicidal period, period 

 from end of germicidal action to time of curdling, period from time of curdling until 

 acidity is neutralized, final decomposition changes. Abnormal fermentations in 

 milk, Gassy fermentation, sweet curdling fermentation, ropy or slimy fermenta- 

 tion, bitter fermentation, alcoholic fermentation, other fermentations. The com- 

 mercial significance of microorganisms in milk, -Relation of dirt contamination to 

 germ content. Milk as a carrier of disease-producing organisms, (acid forms, 

 neutral forms, injurious organisms, epidemic diseases, non-epidemic diseases). 

 Bacteriological analysis of milk. Bacteriological milk standards. The value of 

 bacteriological milk standards and analyses. 



CHAPTER II. THE RELATIONS OF MICROORGANISMS TO BUTTER (Hastings) 47 



Types of butter, Sweet cream butter, sour cream butter. The flavor of butter, 

 Control of butter flavor, kinds and numbers of bacteria in cream, spontaneous ripen- 

 ing of cream, use of cultures in butter making, commercial cultures, use of pure cul- 

 tures in raw cream, use of pure cultures in pasteurized cream, pure cultures in oleo- 

 margarine and renovated butter, abnormal flavors of butter. Decomposition 

 processes in butter. Pathogenic bacteria in butter. 



CHAPTER III. RELATION OF MICROORGANISMS TO CHEESE (Hastings) 486 



General. Types of cheese, Acid-curd cheeses, rennet-curd cheeses. Conditions af- 

 fecting the making of cheese, Quality of milk, tests for the quality of milk, ripening 

 of milk, curdling of milk, manipulation of the curd, ripening of cheese (theories of 

 cheese ripening, present knowledge of causal factors, causes of proteolysis, preven- 

 tion of putrefaction, other groups of bacteria in cheese, flavor production in cheese). 

 Abnormal cheeses, Gassy cheese, miscellaneous abnormalities of cheese (bitter 

 cheese, colored cheese, putrid cheese, moldy cheese). Specific kinds of cheese, 

 Cheddar cheese, Emmenthaler cheese, Roquefort cheese, Gorgonzola cheese, Stilton 

 cheese, Camembert cheese. 



CHAPTER IV. RELATION OF MICROORGANISMS TO SOME SPECIAL DAIRY PRODUCTS 



(Stocking) 504 



General. Condensed milk, Sweetened condensed milk, unsweetened condensed 

 or evaporated milk, concentrated milk, powdered milk. Canned butter, and 

 cheese. Special milk drinks made by the action of microorganisms, Kumyss, 

 kefir, leben, yoghurt, artificial buttermilk. Ice cream. 



