CONTROL OF FOODS 235 



tuberculosis. The magnitude of the task of testing all of 

 the milch-cows each year, the expense connected therewith, 

 and the imperfection of the protection have led to the 

 abandonment of the di-iimnd for the tuberculin testing of 

 all cattle. The presence of dangerous cases of udder inflam- 

 mation may never be recognized until the epidemic of septic 

 sore throat is well under way. 



Under the most ideal system of inspection, the safety of 

 large supplies of milk can not be assured. The pasteur- 

 ization of the milk offers an effective solution of this prob- 

 lem of healthfulness of market milk. The process is almost 

 a necessity under modern conditions as a preservative meas- 

 ure. Without it the provisioning of our great cities would 

 be most difficult, and in some cases impossible. For all of 

 these reasons the introduction of the pasteurization process 

 has been rapid, until more than 90 per cent, of the milk 

 sold in large cities is now pasteurized. 



As previously mentioned, heating causes certain changes 

 in milk. In the treatment of market milk it is desirable 

 to use as low temperatures as will suffice to destroy the 

 disease-producing bacteria. It is fortunate that tempera- 

 tures that will insure this result have little effect on the 

 milk. The State of New York requires that the milk shall 

 be subjected to a temperature of from 142 to 145 F. for 

 not less than thirty minutes, and immediately cooled. The 

 acid-forming bacteria are not completely destroyed, and 

 the pasteurized milk as a rule will undergo the same type 

 of fermentation as raw milk. It is, however, deemed essen- 

 tial that all pasteurized milk be sold as such; that it be 

 delivered to the consumer within twenty-four hours after 

 pasteurization ; and that no milk be pasteurized a second 

 time. 



The continuous pasteurizing machines have the disadvan- 

 tage that a small portion of the milk passes through so 



