mm 



Vol.. XII 



Washington, D. C, March i8, 1918 



No. II 



RESPIRATION OF STORED WHEAT ^ 



By C. H. Bailey, Cereal Technologist, and A. M. Gurjar, Assistant in Agrkultural 

 Biochemistry, Division of Agricultural Biochemistry, Minnesota Agricultural Experi- 

 ment Station 



INTRODUCTION 



The preservation in storage of large quantities of thrashed grain in- 

 volves certain difficulties. In addition to protection from vermin, it has 

 long been known that the grain must be dry when stored, and the ingress 

 of moisture prevented. The ancients were aware that damp grain, or 

 similar vegetable material, will heat and become decomposed when 

 stored in quantities. It is evident that in prehistoric times carefully 

 constructed receptacles were employed for the protection of the reserve 

 supplies of cereals. Those ancient people of India, the Hindus, some- 

 times resort to the use of receptacles which are submerged in cool water, 

 reducing the temperature of the stored grain and also the supply of air. 

 In modern practice carefully constructed tanks or silos, frequently of 

 large capacity, are chiefly used for the storage of grain. 



CAUSE OF THE HEATING OF GRAIN 



The cause of heating of damp vegetable matter was not known, how- 

 ever, until comparatively recent times, and it is only mthin the last 

 decade or two that any data have been accumulated which indicate the 

 exact effect of various factors on the rate of heating of grain and similar 

 material. That the phenomenon known as respiration is responsible for 

 the heat energy released in a mass of damp grain is shown by modern 

 research. Loew (i8pc>y, in discussing the fermentation and heating of leaf 

 tobacco, maintained that the release of energy and rise in temperature 

 was occasioned by the activity of the oxidizing enzyms of the leaf cells. 

 The microbial flora were not believed to play any considerable part in 

 these changes. In advancing this view he opposed vigorously the bac- 

 terial-fermentarion theory of Suchsland {i8gi). 



Rahn {1910) states that the curve of the process of spontaneous heat- 

 ing of organic matter, including grain, would not in itself indicate whether 



00 ' Published with the approval of the Director, as Paper 97, Journal Series, Minnesota Agricultural Experi- 



^ir jnent Station. 



_ 2 Bibliographic citations in parentheses (italic) refer to " Literature cited," pp. 710-713. 



. -J Journal of Agricultural Research, 

 Washington, D. C. 



(685) 



Vol. XII, No. n 

 Mar. 18, 1918 

 Key No. Minn. 26 



