Tables I to IV contain the results of the analyses of the worts and finished fermented products obtained at the various breweries where this investigation was conducted, arranged so as to show readily the changes which took place during fermentation and, in a few cases, the changes which took place during storage. The results are all given in terms of grams per 100 cc, so that a direct comparison of the quantities of any particular ingredient in a definite volume of material may be made. The comparison of the grams per 100 cc of an ingredient in the wort, with the grams per 100 cc in the finished fermented product, is based on the assumption that there is no appreciable change in the volume of the wort during fermentation.

In Table I are given the results of the analyses of 7 malt worts and the beers produced from them. Table II contains the results of the analyses of 2 malt-and-rice worts and 2 malt-and-corn worts, and the beers produced from them. In Table III are given the results of the analyses of 4 porter worts and the finished porters produced from them. The results of the analyses of 9 ale worts and the finished ales are shown in Table IV. In these four tables the extract in the original wort has been calculated by multiplying the alcohol (expressed in terms of grams per 100 cc) by 2, and adding to the product the extract of the beer, porter, or ale (expressed in terms of grams per 100 cc). In the porter and ale worts a percentage of dextrose had been added as brewer's sugar. Since dextrose reduces more copper than does maltose in the determination of the sugars, in order to obtain the true percentage of total sugars it was necessary to calculate the amount of copper reduced by the known amount of dextrose present, and then to calculate the amount of maltose. The results thus obtained are given in Tables III and IV under the heading "Reducing sugars as anhydrous maltose."

Table I.—Analyses of all-malt worts and of the beers made from them.

Table II.—Analyses of malt-and-rice and malt-and-corn worts and of the beers made from them.

Table III.—Analyses of porter worts made from malt, cerealin, and brewer's sugar, and of the porters made from these worts.

Table IV.—Analyses of ale worts and of the ales made from them.

A study of these tables shows very clearly that during fermentation marked changes are brought about other than the mere conversion of sugar into alcohol. While it is well known that these changes take place it seems worth while to consider them here, because no similar study relating to American brewery products has been published. Further since we have the exact analysis of the wort and of the beer which was made from it, we have a special opportunity to examine quantitatively some of these changes, such as the production of alcohol, the fermentation of dextrin, the development of acids, and the losses of protein, ash, and phosphoric acid during fermentation.

In order to study the question of the yield of alcohol, to test the present factor used for the calculation of the solids in the original wort, and to show the approximate amount of dextrin, calculations were made, the results of which are presented in Table V.

Table V.—Changes taking place in the conversion of worts into beers and ales.

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 products 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 fermentation 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 ACID.

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.

Table VI.—Average loss during fermentation.

The results given in Table VI show a great similarity in the changes in all of the products, as there is about the same amount of loss of protein, ash, and phosphoric acid in the beer, ale, and porter worts. There does not appear to be any appreciable loss, however, of either protein or phosphoric acid during the storage or aging period as is shown by the few samples which we have analyzed after storage. This is practically in agreement with the experiment of Bertschinger, [1] whose results show only a very slight increase in alcohol and loss of sugar during the storage period.