VITAMINE CONTENT OF FOODSTUFFS 239 



by us, but was not controlled by animal experiments. The stability 

 of vitamine C against heat depends very much on the nature of its 

 source. Weill and Mouriquand (648) stated that this vitamine is 

 very labile, but noted that lemon juice may be heated to 110C. for 1 

 hour without marked loss in activity. Delf and Tozer (649), co- 

 workers of Chick, carried out investigations on cabbage : heating for 

 1 hour at 60C. decreased the antiscorbutic value about 70 per cent, 

 at 90C, about 90 per cent, while on short heating (20 minutes), at 

 90 or 100C., the activity is decreased only about 70 per cent; we 

 see from this that the chief influence is produced by the time of heat- 

 ing and not by the temperature. Strudwick (650) investigated, in 

 this respect, the influence of cooking in a fireless cooker in which the 

 time of cooking was markedly prolonged. The results showed that 

 a rapid heating is much superior to the above method. 



Delf (651 ) 2 investigated, in the same way, the relationship between 

 cabbage leaves and cabbage juice, showing that in the natural con- 

 dition, vitamine C is much more resistant. Turnip juice (swede) 

 was shown to be far more stable than cabbage juice. Orange juice 

 heated to 130C. lost 50 per cent of its activity. Givens and McClug- 

 age (652) found tomatoes quite resistant to heat. However, if they 

 are heated for 15 minutes or more at 100C, a greater amount, in 

 comparison with the crude material, must be fed in order to protect 

 guinea pigs against scurvy. Aside from heating, oxidation appar- 

 ently also plays a role in the inactivation of vitamine C. Rossi (653) 

 fed guinea pigs on oats and hay sterilized in open kettles at 126C., 

 with the result that the animals died of scurvy. However, a different 

 result was obtained when the food was heated as above in closed 

 kettles; on this food, the guinea pigs were still alive after two months. 

 Delf (I.e. 651) also believed that in the presence of air the inactiva- 

 tion of vitamine C was hastened, and this condition, according to 

 Steenbock, Boutwell and Kent (I.e. 594), and others, plays a part 

 in the destruction of vitamine A. 



The destruction of vitamines by heat depends on still another 

 factor the chemical reaction of the starting material. In this 

 connection, the data are not so certain for vitamine B. While McCol- 

 lum and Simmonds (I.e. 315) reported on the supposed destruction 



2 In comparing the temperature coefficient of the heat destruction of 

 vitamine C with toxins and ferments, Delf concluded that this vitamine 

 must possess a relatively simple chemical structure. 



