THE ACTION OF AMYLASE ON ;STAEH: 101 



amount of extract of malt is added to the starch solution. 

 This reaction, which is known as the hydrolysis, or saccharifica- 

 tion of starch, has been found to be due to an enzyme which 

 has been termed amylase. Before studying the reaction 

 further it will be useful briefly to describe the characteristics 

 and method of preparation of malt. Malt is barley which 

 has been allowed to germinate up to a certain point, after 

 which the process is arrested by heat. 



The processes in the manufacture of malt are as follows : 



(1) Preliminary cleaning, grading, etc. This is effected 

 in ordinary screening and winnowing apparatus, much dust 

 and dirt having frequently to be removed from certain classes 

 of barley, especially those sent from the East. 



(2) Steeping. The clean barley grains are steeped in 

 water in vats until quite soft. 



(3) Malting. The steeped grains are placed on floors and 

 constantly turned over until they begin to germinate. 



(4) When germination has gone far enough the grains are 

 placed on drying floors and finally heated in kilns to a tem- 

 perature not exceeding 230 F. This process has to be 

 carefully conducted and lasts some days ; the malt is then 

 screened to remove the dry rootlets and finally stored. 



Malt will be seen on inspection to differ from barley in the 

 following particulars : The barley grain is hard and difficult 

 to break with the teeth and has no special taste or smell ; 

 the malt, on the other hand, is friable, has a pleasant odour 

 and sweet taste. On separating the barley grain, especially if it 

 has been previously soaked in water, the germ will be readily 

 distinguished at the base of the grain (cf. Plate II). In 

 the case of the malt the germ will be found to have developed 

 some two-thirds of the length of the grain. It is now known 

 as the acrospire. The precise change taking place in the barley 

 grain during the process of malting will be more fully studied 

 in the next chapter ; for the moment it will suffice that in 

 malt we have a substance containing a store of amylase 



