166 CERTIFIED MILK. 



grade known as " Inspected " milk, it should not contain more 

 than 100,000 bacteria per cc. in summer and 60,000 bacteria 

 per cc. in winter. It is unfortunate and confusing to have 

 milk commissions recognize two grades of milk. The technic 

 of the bacteriological examination of the milk is described in 

 Chap. VIII. 



Reporting on samples and keeping records of results is facili- 

 tated by the use of a 3 by 5-inch card printed for the reception 

 of data as follows : 



REPORT OF NUMERICAL DETERMINATION OF BACTERIA IN MILK. 



Dair)'. Reported- .- - _ 



Collected at ...- Date Hour 



Milk drawn at...__ (a. m.) (p.m.). Plated at (a. m.) (p. m.) 



Max. possible age hrs. Temperature when plated___ C. 



Colonies percc.-- - Condition of package 



Chemical examinations . Chemical examinations are generally 

 made monthly. A committee of the American Association of 

 Medical Milk Commissions has made a report on chemical 

 standards, which is very briefly abstracted here (3). Milk rated 

 at 4% fat should range from 3.5% to 4.5%, and 5% milk from 

 4.5'/:' to 5.5% . The Babcock test is recommended, but in case 

 of condemnation for low fat control by the ether-extraction 

 method is desirable. 



Protein estimations are not recommended as a routine. 



It is suggested that regular tests be made for formaldehyde 

 with the sulphuric acid-ferric chloride test, and if the test is 

 positive, that the specimen be distilled and the distillate tested. 

 Borax and boric acid may be looked for by the turmeric test. 

 Tests for salicylic acid, benzoic acid and benzoates may be 

 made four times a year at unexpected intervals. 



It is recommended that tests for heated milk be regularly 

 carried out as a check against the use of undesirable high pas- 

 teurization temperatures, which alone can be detected by test. 



Acidity tests of certified milk are of little importance. lyike- 

 wise, a specific gravity standard need not be set for certified 



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