iv PRESERVED MILK 199 



a temperature as possible, and then kept cool until required for 

 use. Pasteurised milk does not, however, keep as well as does 

 milk that has been almost sterilised, for in the former there 

 remain many more resistant micro-organisms than when the 

 heating has been carried above 100 C. 



A very grave danger lies in the use of pasteurised and 

 partially sterilised milk, particularly for infants, if, as often 

 happens, the heated milk after cooling is not kept at a low 

 temperature so as to prevent the spores forming new cells. 

 If such milk is kept for more than twenty-four hours at room 

 temperature, particularly in summer, before being consumed, it 

 often happens that the bacteria which escape the heating 

 develop to a considerable extent, and Flugge l has shown that 

 the decomposition products that arise from their action on the 

 protein of the milk are often of a poisonous nature, and can be 

 a source of serious danger to infants. The worst of it is that 

 decomposition may have gone very far before the appearance of 

 the milk arouses suspicion. 



The purely physical and chemical changes which, it has been 

 seen above, take place when milk is heated to a high tempera- 

 ture, are also found, although to a less degree, as soon as 

 pasteurisation exceeds 70 C. 



Buddised milk is the preparation invented by the Danish 

 engineer, Budde. The principle of the method is to allow 

 small amounts of hydrogen peroxide to act upon rnilk at a 

 temperature of 50~55. By the action of the peroxydases in 

 the milk, the oxygen of the hydrogen peroxide is rendered 

 active, and destroys bacterial life, so that a milk is obtained 

 which is either sterile, if sufficient hydrogen peroxide has been 

 used, or partially sterile if less has been added. The result in 

 either case is to obtain milk which keeps better. It has been 

 proved that the action of hydrogen peroxide on milk is greater 

 at about 30 than at ordinary temperatures, so that a smaller 

 quantity of the peroxide is needed when the temperature is 

 higher. Budde advises an addition of 0*35 g. of hydrogen 

 peroxide per litre, and the heating to be for at least three 

 hours at 50-55 C. This temperature is not high enough to 

 bring about any of the chemical or physical changes which 

 take place in partially sterilised or highly pasteurised milk. 

 1 ge.itschrift fur Hygiene, 1894, Vol. XVII, p. 272. 



