208 MILK AND ITS HYGIENIC RELATIONS 



used mainly in the process of the manufacture of chocolate, rather 

 than for feeding purposes. 



Goy investigated the composition of dried milk obtained both 

 from America and also prepared locally in Germany. He found 

 that in samples of whole milk, fat and protein were present in 

 almost equal proportions and amounted in each case to 

 approximately 25 per cent, of the total substance, sugar being 

 from 38-40 per cent, of the total content, ash from 6-8 per 

 cent., with a small percentage of water, amounting to about 4 

 per cent. Evidently these proportions will not hold where the 

 milk has been deprived of all or part of the cream, in which case 

 the fat content will be reduced and the content of the other 

 substances proportionally raised. 



Figures were also obtained by Kuhl, who gives Fat, 

 22-26 per cent. ; protein, 25-26 per cent. ; sugar, 34-37 per cent. ; 

 ash, 5-6 per cent. 



Utz gives somewhat similar figures, namely Fat, 26-30 per 

 cent. ; protein, 24-26 per cent. ; sugar, 34-40 per cent. ; ash, 5-7 

 per cent. 



Such figures as are given incidentally in other work are all 

 corroborative of the above. 



Bonnamour (i) states that one litre of milk produces approxi- 

 mately 125 grammes of dried milk, and Goy estimates that 12 

 grammes of powder correspond to 100 c.c. of milk, that is, the 

 proportion is roughly 8 : I, or the powder represents eight times 

 the strength of ordinary milk. This figure is agreed with by 

 numerous other observers, commenting upon the composition of 

 dried milk. 



There is some difference of opinion in regard to the keeping 

 qualities of dried milk, some authors stating that the samples 

 keep for many months, while others do not consider that milk 

 can safely be kept for so long a period. Goy, in his investigations, 

 used some samples which were several months old and found that 

 the material was quite fresh. He carried out experiments with 

 a view to ascertaining some of the physical changes which were 

 likely to have occurred as a result of the drying of the milk. He 

 found that the fat globules had changed in form, and did not 

 emulsify very readily, but on allowing the milk prepared from the 

 powder to stand in a cylinder, the fat rose to the top in the usual 

 manner. Several observers (Goy, Jacquet, and others) comment 

 upon the low degree of acidity of milk prepared from the dried 

 powder. 



Investigations have also been carried out upon the bacterial 

 content of dried milk. Kuhl states that the bacteria are not all 

 killed, and that the bacterial content does not permit of the milk 

 being kept for prolonged periods. Goy appears to consider that 

 bacteria are still present, but he states that the milk is too dry 

 to allow of any bacterial growth. 



