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BULLETIN 183, U. S. DEPARTMENT OF AGEICULTUEE. 



malting. The perfection with which an endosperm undergoes diges- 

 tion depends upon the amount of diastase present and upon the 

 location of the endosperm with reference to the diastatic source. 

 It is the aim of malting to carry the disintegration of the en- 

 dosperm only to that point where cytatic action has been com- 

 pleted and where diastase formation has reached a large total which 

 has been distributed through the grain. Very little starch conversion 

 is desired in the process of malting. Indeed, none is desired, since 

 the sugars thus produced are in part absorbed by the growing plant 

 and not only lost but changed into undesirable products. The low 

 temperatures at which the grain is malted are for the purpose of 



restraining this con- 

 version. Every effort 

 is made to prevent 

 the absorption by the 

 plantlet of the con- 

 tents of the proximal 

 region of the endo- 

 sperm before the 

 enzymatic secretions 

 have reached its dis- 

 tal end and have per- 

 meated the dense 

 starch areas in the 

 upper flanks of the 

 grain. When this is 

 attained the embryo 

 is killed to prevent 

 any further absorp- 

 tion. The object of 

 malting is, therefore, 

 to subject aU parts 

 of the endosperm to 

 the initial effects of enz3rms with as Uttle loss as possible. The ideal 

 condition would be a simultaneous attack upon every cell waU and 

 every grain of starch. This is impossible with the source of the 

 action localized at one extremity of the grain. However, the coordi- 

 nation of the scutellum with the endosperm has a marked effect. 



The shape of the grain with reference to the size and shape of the 

 associated embryo has in more than one variety been the deciding 

 factor between a good and a poor malting barley. If the great mass 

 of the starch be near the embryo, as in the short, thick grain shown 

 in figure 4, the disintegration of the endosperm is readily and uni- 

 formly accomplished, but if it be distant, as in long, slender grains, 

 the complete modification of the endosperm mass can not be accom- 



FiG. ■!.— Two grains of aBohomian barley; a broadly oval-shaped grain 

 well adapted to malting with little loss. 



