I5O PRACTICAL DAIRY BACTERIOLOGY 



destroys most of the bacteria that fail to produce spores. The 

 acid bacteria are thus killed since they are not spore producers. 

 Such boiled milk will keep for a much longer time than ordinary 

 milk. Inasmuch, however, as it contains bacterial spores these 

 will in time develop and cause its destruction. The milk is, 

 therefore, not really sterilized. It should be called boiled milk, 

 but in popular language the word sterilization is frequently 

 applied to simple boiling. 



At one time there was a vigorous attempt made to place upon 

 the market absolutely sterilized milk. This product was sealed 

 in bottles and subjected to heat of steam under pressure, and 

 since it was sterilized it was supposed to keep indefinitely. 

 Milk sterilization has undergone a variety of changes in public 

 opinion, but at the present time it has become almost wholly 

 abandoned as a method of treating milk on anything like a 

 large scale. The sterilization of milk produces a number of 

 chemical changes, which seem to interfere with its digestibility, 

 so that the weak stomachs of infants and invalids cannot so 

 easily digest and assimulate it. While many experiments have 

 shown that sterilized milk is capable of perfect digestion by 

 strong, vigorous persons, the evidence is fairly abundant that 

 for weak stomachs it is not as satisfactory a food as raw milk. 1 

 Sterilized milk, moreover, has the taste of boiled milk, which is 

 unpleasant to many people. It has also been found that in spite 

 .of the high heat and the greatest care even such highly heated 

 milk is not always sterilized and, hence, will not keep. 2 Tests 

 of the milk from many companies showed none in which the 

 milk could be relied upon as always sterile, and if it could not 

 be depended upon, the value of the process was practically 

 nothing. 3 



1 Doane and Price. Bui. 77, Md. Agri. Exper. Sta., 1901. 



Dukes. Lancet, p. 1857, 1901. 



Variot. Rev. Gen. d'Lait, iv., p. 238, 1905. 

 spliigge. Zeit. f. Hyg., xvii., p. 272, 1894. 

 3 Weber. Hyg. Rund., p. 688, 1901. 



Sidler. Arch. f. Hyg., xlvii., p. 327, 1903. 



