268 CITY MILK SUPPLY 



transit. The inspection of dairies was not common so that a large part 

 of the milk was unclean to start with and much of that which was not so, 

 was likely to be en the verge of souring when it reached the city. More- 

 over the large contractors were confronted with the problem of supplying 

 summer resorts with milk shipped from their city plants. Added to this 

 was the menace of communicable disease. Previous to 1881, it was not 

 generally known that milk could carry infection but thereafter epidemics 

 had with increasing frequency been traced to milk and besides it was 

 then the general opinion of physicians that dirty milk was a potent 

 cause of infant morbidity. It was apparent that the system of milk 

 supply in vogue lent itself to, rather than impeded, the spread of some 

 kinds of sickness. 



Under these conditions pasteurization, whereby the milk was heated 

 to a temperature high enough to kill most of the lactic acid bacteria and 

 all of the disease germs, appealed forcefully to the city milk dealers. It 

 is difficult to fix the date at which the commercial pasteurization of milk 

 was actually begun. Apparently it was first used in New York State 

 where certain manufacturers of condensed milk who were also in the city 

 milk business, found that the keeping powers of milk were enhanced and 

 no detectable flavor was imparted to it by heating it for a brief period to 

 167F. which temperature was later reduced to 140F. In Baltimore one 

 dealer pasteurized milk for infants as early as 1893, but it was not till 

 about 1904 that any part of the general supply was pasteurized. Pas- 

 teurizing was begun in Cincinnati in 1897, in New York in 1898, in Phila- 

 delphia in 1899, in St. Louis in 1900, in Milwaukee in 1903, in Boston and 

 in Chicago in 1908. The prime object was to prolong the power of milk 

 to keep. Within limits this is perfectly legitimate and commendable. 

 We do not hesitate to keep eggs, butter, cheese and a host of other things 

 by putting them in cold storage, nor to preserve fruits and vegetables by 

 canning them. In fact it would be a senseless waste not to thus conserve 

 our food supply. This is as true of milk as of any other food and can only 

 be rationally objected to on two grounds, namely: first, that the milk is 

 held so long that either its food value becomes impaired or that while 

 apparently usable it has in fact become injurious; and second, that the 

 process is used to defraud the consumer by making it possible to sell him 

 milk so inferior that if the normal course of decomposition was not inter- 

 fered with, the milk would reach him in such a state that he would not 

 buy it. 



The contractors generally adopted the flash process of pasteurization. 

 At first high temperatures were used but it was found that the milk ac- 

 quired a cooked taste. The exact temperature at which this flavor becomes 

 perceptible to the consumer varies with the degree of heat employed, the 

 time exposure and the acuteness of taste of the consumer but for most 

 people is at about 158F. It was also found that a minute's exposure at 



