POMACES 383 



sarily contain more sugar than "sour apples," but they do 

 contain less acid, hence their "sweetness." 



Cider and Vinegar.— Cider is the juice or wine of apples. 

 In the transformation of cider to vinegar, two fermentation 

 processes take place, in the following order: (i) alcoholic 

 fermentation, and (2) acetic acid fermentation. When cider 

 "begins to work," it is an indication that the first fermenta- 

 tion process is going on. The sugar of the apple juice is being 

 converted into alcohol and carbon dioxide. The escaping 

 of this gas from the fermenting cider causes a "frothing." 

 The process of alcoholic fermentation is produced by a micro- 

 scopic organism, the yeast plant. When the evolution of 

 carbon dioxide gas has ceased and the alcohol is at its maxi- 

 mum, the cider is spoken of as hard cider. The second step 

 in vinegar-making is the conversion of the alcohol of the hard 

 cider into acetic acid. This change is brought about by a 

 bacterium, the acetic acid germ. The characteristic prop- 

 erties of vinegar are due to acetic acid. 



Dried Apples. — The output of dried apples in the United 

 States in 1909 was 44,000,000 pounds. Many housewives 

 dry their apples in the sun. When apples are dried on a 

 large scale, they are peeled, cored, and sometimes sliced by 

 machinery. The fruit is then dipped for a few minutes in a 

 weak salt solution, which tends to prevent discoloration. It is 

 then placed in trays and taken to the drying machine. It is 

 the practice in some manufacturing plants to subject the 

 apples, before drying, to sulphur fumes for a short time. 

 These fumes bleach the apples slightly, and also kill any or- 

 ganisms that may be present. The most common drying 

 method is to pass hot air under high pressure over the fruit. 

 After removal from the drying machine, the apples are al- 

 lowed to sweat for several days either in the open air or in 

 well-ventilated chambers. They are then ready for packing. 



