FOODS 83 



up slowly into water and free oxygen, and so after six to 

 eight hours will not be found. 



Pasteurized Milk. By this term is meant milk which 

 has been heated to a temperature sufficient to kill the less 

 resistant pathogenic bacteria without altering the flavour. 

 The temperature used varies from yo to 85 C. (158 to 

 i85F.). The higher temperature has been advised by 

 Professor Bang. The one mostly used is 75 C. (167 F.) for 

 half an hour, cooling quickly thereafter. Over 90 per cent 

 of the organisms are killed, but the sporing forms are 

 not destroyed. Souring of pasteurized milk does not take 

 place owing to the destruction of the lactic acid bacilli. 

 It does not keep for more than three days. 



Buddeized Milk. Fifteen c.c. of a 3 per cent solution 

 of hydroxyl are added per litre of milk (1 of H 2 2 in 2222), 

 and the mixture heated for three hours at 51 C. (123-8 F.). 

 Milk so treated is normal in taste, and keeps fresh for 

 eight days, even in hot weather. 



Homogenized Milk. Under 200 to 400 atmospheres' 

 pressure, milk is forced through very small openings, and 

 the size of the fat globules reduced to o-ooi mm. in 

 diameter. This prevents the fat from rising. Adams' 

 process gives too low an estimate of fat in such milks. 



Dried Milk. By passing a thin layer of milk between 

 two heated rollers, the milk is immediately desiccated and 

 reduced to a fine powder, which merely requires the addi- 

 tion of water to bring it back to the condition of ordinary 

 milk. The temperature of the rollers is no C. (230 F.). 

 Such milk may be lacking in the antiscorbutic properties 

 necessary for infants, but appears to possess all the solids 

 of the original milk in a sterile form. 



Humanized Cow's Milk. This is prepared on the large 

 scale by diluting the milk with an equal quantity of pure 

 water, and subjecting the mixture to centrifugalization. 

 This divides it into two equal parts, one of which contains 

 practically all the fat of the original milk, but only half of 

 the other ingredients. The only constituent, therefore, 

 notably deficient, will be the sugar, which is added in the 

 proper proportion. The amount of proteid tends to be 



