IQ2 ADDENDUM 



While admitting that the question is undecided he gives his 

 opinion that the presence of Staphylococcus pyogenes aureus in 

 large numbers in a sample of condensed milk is objectionable 

 and a ground for its condemnation. 



Delepine 1 investigated the effects of certain condensing and 

 drying processes upon the bacterial content of milk subjected to 

 them. The three processes studied were : (A) The preparation 

 of sweetened condensed milk, condensed by evaporation in 

 vacuo at 4O-45 C. ; (B) the preparation of dried milk by 

 passage between heated revolving cylinders, and (C) the pre- 

 paration of dried milk by spraying the milk into a current of 

 hot air. 



In all three processes the total number of bacteria in the 

 original milk was markedly reduced, most by Method A, least 

 by Method C. In each of the three methods of treatment there 

 was a stage in which the reduction in the total number of 

 bacteria was much greater than that observed in the finished 

 article ready for sale. The increase in the number of bacteria 

 observed during the final stages was due to recontamination 

 subsequent to the partial or complete sterilization stages. The 

 reduction in the total number of bacteria was almost entirely 

 due to the death of streptococci, staphylococci, sarcinae, bacilli 

 of the B. coli type, streptothrichae, yeasts, etc. At none of the 

 stages of preparation was the milk ever found completely sterile. 

 The amount of heat to which the milk was subjected was 

 insufficient to bring about the death of several saprophytic and 

 of some pathogenic bacteria. Among the saprophytic bacteria, 

 which were invariably found to resist pasteurisation, those most 

 commonly detected were sporing bacilli of the types included 

 under the term B. mesentericus. Some streptothrichae appeared 

 to have survived in some cases, but the evidence on that point 

 was not conclusive. 



Careful investigation was made as to the efficiency of the 

 methods to kill tubercle bacilli. Naturally infected tuberculous 

 milk was used, fortified by the addition of numerous tubercle 



1 Report to the Local Government Board upon the effects of certain condensing 

 and drying processes used in the preservation of milk upon its bacterial contents : 

 Food Reports, No. 21, 1914* 



