194 Effect of Heat. 



diminishes, which, according to Kida, may be seen from the fol- 

 lowing example: 



In 1000 c. c. of milk, lecithin was present as follows : 

 Unheated samples... 0.474 gm. 0.474 0.505 0.467 0.462 0.517 



Heated to 75 deg. . . .0.444 gm 



Heated to 80 deg 0.420 0.467 



Heated to 95 deg 0.349 



Heated to 100 deg 0.351 



Over 100 deg. C 0.401 



Diminishing amt. ...0.030 gm. 0.054 0.038 0.118 0.111 0.116 

 In percentage 6.33 11.39 7.52 25.27 21.22 22.17 



In heating, the proteids also change, peptone is formed and 

 tricalcium phosphate is precipitated. 



The original ferments are especially susceptible to the influ- 

 ence of heat. Through heating to a certain temperature the 

 amylase, the peroxydase, the catalase and the aldehyde reductase 

 disappear. The amylase and the aldehyde reductase disappear 

 even at a temperature of 65, that is from 50-65 deg. C. Of course 

 milk which has been changed in this way by heat must naturally 

 be judged differently from a nutritive standpoint than raw milk. 

 Out of 3,462 digestible proteids used in each 100 gm. of milk there 

 remained undigested: 



In unheated milk 0.762 gm. 



In heating for 30 min. to 80 deg. C 1.153 gm. 



85 deg. C.... 1.493 gm. 



90 deg. C.... 1.420 gm. 



95 deg. C.... 1.540 gm. 



100 deg. C.... 1.719 gm. 



Experiments by Briickler, Eeiner and Eichloff showed that 

 dogs fed for months on sterilized milk showed a good nutritive 

 condition, and some of them even manifested a greater gain in 

 weight than the control dogs fed with raw milk, but the latter 

 were brighter, their blood was richer in ash, with diminished salt 

 content; it contained more fibrin, had a higher specific gravity, 

 and the structure of their bones was more dense and richer in 

 ash. The bone marrow of the animals fed with sterile milk was 

 more anemic, the periosteum of the bones separated more easily, 

 and at times hemorrhages appeared on the borders of the 

 diaphyses, such as occur in rachitis. 



The nutritive results in children which have for a long time 

 been exclusively nourished on sterilized milk are similar. The 

 infants become affected with infantile scorbutus, a symptom com- 

 plex, which is known to the physician as "Moller-Barlow disease," 

 and which disappears when raw milk is provided. 



From the above it appears that high prolonged heating of 

 milk should be avoided, and if possible the advantages derived 

 from the heating should be obtained by heating the milk for only 



