RYE AND BARLEY. 



129 



Rye flour more nearly resembles wheaten flour in 

 its composition than any other; it has, however, more 

 of certain gummy and sugary substances, which make 

 it tenacious, and also impart a sweetish taste. In 

 baking all grains and roots which have much starch 

 in them, a certain change takes place in their chemi-« 

 cal composition. 



If starch be taken and exposed to a carefully gra- 

 duated heat for a few days, it will be found to have 

 changed its character, to have become partially soluble 

 in water, and also a little sweet. By the action of 

 heat it has been converted into a species of sweetish 

 gum, called dextrine. This is the change which 

 occurs in baking; a portion of the starch is altered 

 into this gum or dextrine, communicating the sweetish 

 taste which is observable in good bread. By baking, 

 then, flour becomes more nutritious, and more easily 

 digestible, because more soluble. This alteration hap- 

 pens probably in baking any grain, but as wheat and 

 rye are more used for making bread than other grains, 

 we are better acquainted with the transformations 

 which occur in them through the agency of heat. 



Barley contains rather less starch than wheat, also 

 '.ess sugar and gum. There is little gluten, but a sub- 

 stance somewhat like it, and containing about the 

 same amount of nitrogen. 



a. The malting of barley depends on a peculiar 

 change which takes place during germination, or the 

 sprouting of the seed. The starch, forming the prin- 

 cipal part of it, and of all or nearly all grains, is, as 

 we know, insoluble in water; how then is it to be of 

 use in nourishing the young shoot? 



b. When the seed, moistened by water, and warmed 

 by the summer sun, swells and pushes forth its shoot, 

 a peculiar substance called diastase is formed, which 

 has the property of changing starch into sugar. This 

 sugar is of course soluble, and goes at once into the 



