90 THE MILK SITUATION IN THE DISTRICT OF COLUMBIA. 



practice has, he reports, been tried in some parts of Europe " without 

 satisfactory success." Borden's Condensed Milk Co. states that 

 freezing itself has really no effect whatever on the quality of milk, 

 provided the milk in being restored to its normal condition is care- 

 fully mixed. Milk; however, does not, it goes on to state, keep indefi- 

 nitely in a frozen condition, as certain forms of bacteria multiply 

 even in that condition, while the lactic acid bacteria are entirely 

 dormant. Bacteria are not, however, destroyed by freezing, even 

 when the frozen condition extends over a period of time. Dr. Pres- 

 cott observes that frozen milks are sold in Europe and used with 

 apparent impunity. 



Dr. Wiley, Chief of the Bureau of Chemistry, United States De- 

 partment of Agriculture, states that while he has not made experi- 

 mental determinations on the effect of freezing milk, he is of the 

 opinion that it profoundly modifies its character, perhaps not so 

 much in regard to its potability (that is to say, its quality for drink- 

 ing purposes) , as to its wholesomeness and nutritive qualities. His 

 belief in the matter is, he avers, based on the well-known fact that 

 the freezing of wine or beer, or of meats or fruits, profoundly affects 

 their character, for which reason, in his judgment, milk, especially 

 if intended for the nutrition of infants, should never be frozen. 



VII. PASTEURIZATION. 



PASTEURIZATION AND STERILIZATION DEFINED. 



Pasteurized milk is defined in the Standards of Purity for Food 

 Products, 1 issued by the Secretary of Agriculture in pursuance of 

 authority given by Congress in the food and drugs act of June 30, 

 ^906, as follows : 



Pasteurized milk is milk that has been heated below boiling, but sufficiently 

 to kill most of the active organisms present, and immediately cooled to 50 F. 

 or lower. 



Sterilized milk is defined in the same publication as follows : 



Sterilized milk is milk that has been heated at the temperature of boiling 

 water or higher for a length of time sufficient to kill all organisms present. 



The term " pasteurization," as applied in a commercial sense, has 

 been employed to denote all cases where milk is subjected to heat 

 with the view, actually or ostensibly, as the case may be, of eliminat- 

 ing all prejudicial germ life, though with the real purpose in many 

 instances of complying constructively, though not effectually, with 

 the requirements of law and of an awakened public that it be sub- 

 jected to the pasteurizing process to give assurance of its freedom 

 from live deleterious organisms. So variant have been the methods 

 employed for pasteurizing milk, both as to the degree of heat to 

 which exposed and the term of exposure, that many authorities have 

 suggested the coinage, or application at least, of some new term to 

 express pasteurization when effected in the manner agreed by compe- 

 tent bacteriologists as calculated to destroy the pathogenic micro- 

 organisms without at the same time destroying the nutritive value 

 of the milk and its facility of digestion. 



i Circular No. 19, Bureau of Chemistry, U. S. Department of Agriculture. 



