VITAMINE CONTENT OF FOODSTUFFS 259 



The influence of heat on the vitamine content of milk 



Practically all of the studies related to this point were made with 

 vitamine C. In this respect, most workers agree that the use of 

 heated milk may result in scurvy. Some investigators, on the con- 

 trary, believe that the decrease in the nutritive value after heating 

 cannot be attributed entirely to the vitamines. McCollum and 

 Davis (I.e. 97) stated that this is related to an injury of the casein 

 by heat. We have already mentioned this explanation and experi- 

 mentally disproven it. Daniels and Stuessy (761) showed that rats 

 fed on milk, cooked for 1 minute, could not grow. This experiment 

 was repeated, varying the temperature and time of heating. They 

 found, at the time, that an addition of protein, in the form of casein 

 or egg-yolk, permitted the rats to resume growth. In a recent paper, 

 Daniels and Loughlin (762) report that the results of Daniels- 

 Stuessy with casein and egg-yolk were to be attributed simply to an 

 addition of calcium salts. They found that when milk is heated 

 slowly at a lower temperature, as in pasteurization, a deposit con- 

 taining calcium salts is formed in the kettle. If the milk is quickly 

 boiled up, or if care is taken to mix the above deposit in with the 

 milk, then the rats grow just as well as on unheated milk. The same 

 results were obtained when soluble calcium salts, like calcium glycero- 

 phosphate, were added to the heated milk. Regarding the signifi- 

 cance of the results of Daniels and Loughlin critically, they maintain 

 that the decrease in the nutritive value of milk after heating is due, 

 not to the destruction of B- and A-vitamines, but to the precipitation 

 of calcium salts. Although the destruction of vitamine C is not 

 touched upon in this work, the investigators wished to convey the 

 impression that the changes of the milk on cooking had nothing to 

 do with the vitamines. It is not impossible, however, that if they 

 would repeat their work, using children, as they proposed to do, the 

 results would be different from those with rats. 



The first investigation on the influence of heating on vitamine C 

 was made by Frolich (763). Milk heated at 98 C. for 10 minutes 

 lost its protective action against guinea pig scurvy, while heating at 

 70 C. for 30 minutes gave uncertain results. Whereas the author 

 found that 50 cc. milk prevented scurvy in guinea pigs, Chick, Hume 

 and Skelton (I.e. 751) observed that this was not sufficient. Barnes 

 and Hume (764) investigated the effect of heating, drying and rapid 



