lo() FLAVORING AND BEVERAGE PLANTS 



uents. A small amount of a tannin-like suljstance is found 

 also in coffee, and in cacao. Cacao, although used as a bev- 

 erage, is so nutritious that it should be regarded rather as a 

 food than as a food-adjunct. 



58. Alcoholic beverages and stimulants in general. Alco- 

 holic beverages are either fermented or distilled. 



Fermented beverages include beers or malt liquors, and wines. 

 Beer, as already stated (sections 19 and 29), is made by fer- 

 menting a sweet liquid obtained chiefly from barley malt. In 

 much the same way that the diastase in the sprouting grain 

 changes the starch into sugar, an enzyme contained in the yeast 

 which is added to the sweet malt liquid, changes its sugar 

 into alcohol and the gas known as carbon dioxid. Yeast 

 is a plant consisting of exceedingly minute bodies of the form 

 shown in Fig. 151. These multiply very rapidly under 

 favorable conditions of food supply and temperature. Hence 

 a small amount of yeast added to a vat full of malt liquid 

 soon becomes a considerable quantity. When the fermenta- 

 tion is well under way the liquid is put into air-tight kegs or 

 ])ottles so that the gas produced may be retained. When 

 the beer is poured out this gas rises to the surface and forms 

 bubbles of foam. After the sugar is converted into alcohol 

 and carbon dioxid gas, the alcohol may be turned into acetic 

 acid (the acid of vinegar) by a plant similar to 3'east (see 

 Fig. 152) unless its action is prevented. This is accompHshed 

 mainly by the addition of hops (Fig. 153) which at the same 

 time impart their peculiar flavor to the beer and give it a 

 bitter taste. The preservative action as well as the flavor of 

 the hops is due chiefiy to a volatile oil of which the fruit con- 

 tains about 1%. The stupefjdng effect of beer is also believed 

 to be due in large part to the flavoring materials derived from 

 the hops. Malt liquors contain about 4-10^^ of alcohol. 



The process of fermentation may be observed readily by 

 adding j^east to water sweetened with molasses and keeping 

 the mixture for some hours in a warm place. Bubbles of 

 carbon dioxid are given off abundantly and a faint smell of 

 alcohol may be detected. If some of the fermenting mixture 

 be boiled in a flask to kill the 3'east, the neck of the flask being 

 plugged with a wad of cotton wool (which will permit th*" 



