70 MAINE AGRICULTURAL EXPERIMENT STATION. I915. 



A Study of the Conditions of Home making of Vinegar 



Bulletin 258 of the New York Agricultural Experiment Sta- 

 tion gives in detail the results oif a study of the chemistry of 

 home-made cider vinegar, which extended over a number of 

 years. The following is based upon or directly quoted from 

 that bulletin. Quotation marks are not used. The indirect 

 quotations from the bulletin but are as much a part of that 

 study as the, direct quotations. 



The sour taste of vinegar is due to acetic acid. Acetic acid 

 is formed from dilute alcohol by the action of yeast. The flavor 

 of cider vinegar is due to the aipple solids in solution and to 

 certain etherial bodies developed in the process of fermentation. 

 The acid strength and the flavor of vinegar are dependent upon 

 the quality of the cider and the methods of fermentation. 

 Sugar is the most important constituent of apple juice from the 

 standpoint of the vinegar maker. The quantity of sugar in 

 apple juice is dependent upon the variety of apple and upon the 

 stage of ripeness, unripe or over-ripe apples containing less 

 sugar than ripe apples. 



ALCOHOLIC fermentation 



Apple juice left exposed to the air is acted upon by yeast 

 cells everywhere present, the sugar being changed into alcohol 

 and carbon dioxide gas. Theoretically, 100 parts of sugar 

 should yield a.bout 51 parts of alcohol, but in actual practice 

 losses are experienced, reducing the actual yield to 45 to 47 

 parts of alcohol. The fresh apple juice from sound apples con- 

 tains no alcdhol. 



Under the ordinary conditions of a cellar temperature, most 

 of the sugar is changed into alcohol in five or six months." The 

 higher the tem,perature up to about 80 degrees Fahrenheit the 

 more rapid the change of sugar to ako'hol. Adding yeast to 

 apple juice tends to- hasten the alcoholic fermentation. 



