454 FIELD AND GARDEN PRODUCTS 



mixed with the good and the grade of the whole is lowered. Such 

 exposure and the resulting change in appearance have a direct and 

 immediate effect upon the market value of the grain. The grade 

 that is given to wheat upon the terminal markets depends to-day 

 almost wholly upon its appearance, condition, and test weight per 

 measured bushel. When the natural color or "bloom" of the kernel 

 has been destroyed by rain and sun while standing in the shock and 

 the increase in moisture content has caused a corresponding decrease 

 in the test weight per bushel, the grade given is lower than it would 

 be if this same wheat were marketed in good condition without de- 

 terioration resulting from exposure to the weather. It is common 

 knowledge among farmers that wheat standing in the shock may 

 readily lose a pound per bushel in test weight on being exposed to 

 a heavy shower. This is especially true where the wheat has been 

 carelessly shocked and is not protected by cap bundles. 



Effeet of Exposure to Weather. In addition to causing the 

 bleached appearance and lowering the test weight, the exposure of 

 wheat to rain and sun while standing in the shock causes many of 

 the kernels to sprout, and sprouted wheat will not produce good, 

 sound flour. Furthermore, the indications are that this excess 

 moisture acquired by exposure in the field after harvest continues to 

 be a source of injury to the quality until the wheat is dried either 

 artificially or by natural means. 



Sweat in Wheat. Millers, as well as operators of country and 

 terminal elevators, prefer wheat that has gone through the sweat. 

 The millers invariably hold that sweating in the stack improves 

 weathered grain and is much to be desired. Comparatively little is 

 known as to what the process commonly referred to as sweat of 

 wheat consists of. Very little information concerning it can be 

 gleaned from scientific literature. The following has been ad- 

 vanced as a possible explanation of the change that takes place 

 during the process. It is known that even after wheat is cut the 

 straw contains sufficient plant food to keep the kernels in a growing 

 condition for some time, and a chemical or enzymic action within 

 the plant by means of which this nutriment is transferred to the 

 grain and stored as starch may continue for a considerable period. 

 When wheat has been thrashed before going through the sweat, it 

 is probable that a rearrangement of the chemical constituents of 

 the kernels still takes place, and this will account for the sweating 

 of shock-thrashed grain in the bin. 



As chemical action is generally accompanied by the evolution 

 of heat, this may account for the heat usually generated during the 

 sweating process. The amount of heat generated appears to be in- 

 fluenced by the percentage of moisture present. Grain that has 

 been sufficiently ripened and is also very dry will give little evi- 

 dence through change in temperature that it is going through the 

 sweating process. On the other hand, wheat cut in the hard-dough 

 stage, or containing considerable moisture, goes into the sweat much 

 more quickly when stacked; the straw becomes very tough and a 

 great deal of heat is evolved. Care should be exercised not to stack 



