Temperatures at or above 100° C. upon Vitamines. 61 



The fate of the vitamines during this treatment becomes a vital matter where 

 preserved foods form the staple article of a diet, as may be the case with 

 troops on active service, separated from fresh food supplies. 



In such circumstances the ration is usually completed with bread or 

 biscuit, and we have made a special investigation of the wheat-grain and its 

 various constituents in order to gauge the value of the bread or biscuit in 

 such a diet. The results of these experiments are given in a separate 

 communication* which contains references to the general literature of beri- 

 beri, and to which the reader is also referred for a detailed description of the 

 methods employed in the present work. 



Polyneuritis of birds has been accepted as the complete analogy of beri- 

 beri in man and, for the sake of brevity, we shall refer to the substance 

 whose absence in a diet occasions polyneuritis in birds, or beri-beri in man, as 

 the " anti-neuritic vitamine" (or anti-beri-beri vitamine). As regards the 

 influence of high temperatures upon this substance, a great number of 

 isolated observations exists in the literature, but no one hitherto seems to 

 have attempted any systematic study of the point. Grijns(1901) showed that 

 1-2 hours' exposure to 120° C. destroyed the protective properties against 

 polyneuritis of uumilled rice, " Katjang idjo " beans, and buffalo meat. 

 Eijkman (1906) confirmed Grijns' results as far as unmilled rice was 

 concerned, but did not succeed in destroying the anti-neuritic properties of 

 horse-flesh by heating for two hours at 120° C. Schaumann (1910), however, 

 induced polyneuritis in dogs with a diet of horse-flesh heated 1-3 hours at 

 120^-130° C, and Hoist (1907) traced a loss of anti-neuritic vitamine in beef 

 after heating to 110° C. for half-an-hour ; this loss was much more marked 

 after one hour at 120° C. In the case of dried peas or uupeeled barley, on the 

 other hand; kept for half-an-hour at 11.5° C, no particular damage was done. 

 Most observers have not detected any destruction of vitamine at 100° C. 



In these and other experiments, the temperatures noted appear to be those 

 registered by the autoclave or steamer used, no measurement being apparently 

 made in the interior of the substance heated. This is an important point, as 

 the latter temperature remains for a surprisingly long time far below the 

 former (see Table I), especially if the material investigated has a low 

 conductivity, which is true of most foodstuffs, especially if fairly dry. 

 ■ Further, no attempt has been made to investigate the time relations of the 

 destruction process of the vitamine. This is obviously an exceedingly 

 difficult problem, seeing that the only available instrument for measurement 

 is so very imperfect. Nevertheless it seemed worth while to make the 

 following effort. 



* The preceding paper. 



G 2 



