RESULTS OF PASTEURISATION 



539 



milk, but any specific toxic action brought about by boiling milk 

 is probably very slight (Halliburton). There is a further dis- 

 advantage which must not be lost sight of. Pasteurisation kills 

 off the normal acid-producing organisms in milk, and, in addition, 

 many ordinary saprophytic and fermentative bacteria, but it cannot 

 be relied upon to destroy the more resistant, which are therefore 

 left behind in the milk unchecked by their antagonists, and under 

 favourable conditions for multiplication. Fliigge and other workers 

 have isolated such organisms, some of them anaerobic and sporu- 

 lating, from pasteurised milk. 



Results of pasteurisation. — Before leaving this subject we may 

 glance for a moment at the bacterial results of pasteurisation and 

 sterilisation. The two chief of these are the enhanced keeping 

 quality and the removal of disease-producing germs. The former 

 is due in part to the latter, and also to the removal of the lactic 

 acid and other fermentative bacteria. As a general rule, these 

 bacteria do not produce spores, and hence they are easily annihi- 

 lated by pasteurisation. True, a number of indifferent bacteria 

 are untouched, and also some of the peptonising species. The 

 cooling itself contributes to the increased keeping power of the 

 milk, especially in transit to the consumer. 



Pasteurised milks have the following three economical and 

 commercial advantages over sterilised milks, namely, {a) they are 

 more digestible ; (J?) the flavour is not altered ; {c) and the fat and 

 the lact-albumen are unchanged. Professor Hunter Stewart of 

 Edinburgh, about three years ago, compiled from a number of 

 experiments the following instructive and comprehensive table : — 



