12 A TEXT-BOOK OF GRASSES 



ALCOHOL 



11. Another important product of the grains is alco- 

 hol. — For this purpose the starch is first converted by 

 means of diastase into maltose, a kind of sugar, and the 

 sugar is fermented by means of a yeast plant. The fer- 

 mented liquor is distilled, the product being alcohol. The 

 diastase is an unorganized ferment present in the germi- 

 nating grains. This converts the stored starch of the 

 seed into a soluble form, a sugar, which can be absorbed 

 by the young plant. The grain to be used as a source of 

 alcohol is allowed to germinate, is heated to kill the 

 embryos, and is then fermented with yeast. This con- 

 verts the sugar into alcohol and carbon dioxide. If beer is 

 the product desired, barley is the grain usually employed 

 and the process is stopped at this point. If a distilled 

 liquor is desired, the material is distilled. The details of 

 the manufacture of the various alcoholic products belong 

 to the study of industrial chemistry. Wine is produced by 

 fermentation from the juices of fruits containing sugar, 

 especially the juice of the grape. This liquid, when dis- 

 tilled, produces a brandy. 



MISCELLANEOUS USES OF THE GRAINS 



12. In the manufacture of starch or alcohol, the grains 

 furnish many other substances, often as by-products. 

 Among these may be mentioned gluten meal and corn 

 oil, the one from the protein and the other from the fat 

 of the seed. Corn oil is expressed from the grain before 

 the starch is extracted, or it is obtained from the residue 

 in the fermentation vats in the manufacture of alcohol. 

 Much of the commercial vinegar is produced from malt 



