10 BULLETIN 493, U. S. DEPARTMENT OF AGRICULTURE. 



In Table V have been collected results (calculated from Tables 

 I-IV) which show the loss in solids between the wort and the finished 

 fermented product, the loss in sugar, the yield of alcohol, the loss in 

 solids divided by the alcohol, and the difference between the loss in 

 solids and the loss in sugar. By dividing alcohol into loss in solids 

 there was secured a factor which makes possible the estimation of the 

 solids in the original wort, provided that alcohol and extract are known. 

 This factor also shows the yield of alcohol for a given amount of 

 solids disappearing during fermentation. It has been found in the 

 case of the beers that this factor averages 2.14, while in the case 

 of the ales it averages 2.12, making an average for all of the prod- 

 ucts of 2.13. This clearly shows that in the yield of alcohol for a 

 given amount of fermentable solids there is no appreciable difference 

 between top fermentation products, such as ales, and bottom fer- 

 mentation products, such as beers. 



A marked difference in loss in solids is shown, however, when we 

 compare the beers with the ales. In the case of the beers we find 

 there is practically no difference between the loss in solids and the 

 loss in sugar, while in the case of the porters and ales there is a very 

 appreciable difference. The difference between the loss in solids and 

 the loss in sugar is only 0.04' per cent for all of the beers; while in 

 the case of the porters and ales the difference varies from 1.47 per 

 cent to 2.65 per cent, with an average of 1.96 per cent. These figures 

 clearly show that in the case of the porters and ales there has been 

 some material other than sugar fermented. Unfortunately, the 

 determination of dextrin was not made in all of the worts, so that the 

 actual decrease in dextrin can be shown only in a few cases. But in 

 those cases where we have the actual results the difference between 

 loss in solids and the loss in sugar compares very closely with the 

 actual amount of dextrin disappearing during fermentation. 



DEVELOPMENT OF ACIDS DURING FERMENTATION. 



A comparison of the amounts of volatile and fixed acids in the 

 worts and in the finished beers shows that normally there is no 

 appreciable development of volatile acid during fermentation and 

 only a slight increase in the fixed acid. This increase in fixed acid 

 averages in the case of the beers 0.049 per cent, while in the case of 

 the ales the increase averages 0.103 per cent. 



DECREASE IN PROTEIN, ASH, AND PHOSPHORIC ACDD. 



A general study of the preceding tables will show that there is an 

 appreciable loss of protein, ash, and phosphoric acid during the 

 fermentation. Table VI has been prepared to show the average loss 

 during fermentation of the various classes of worts with respect to 

 their protein, ash, and phosphoric acid contents. 



