Chapter VII · New Process for the Manufacture of Beer. (continued 2)
Frank Faulkner translation
In the course of the summer of 1875 we made the following observations on the keeping qualities of a beer brewed on the new system, all the details of which had been rigorously carried out. The beer brewed at Tantonville during the months of June and July, at a temperature of 13° C. (55·4° F.), in 50-litre and 80-litre casks (11 and 18-gallon), had been sent by slow trains to Arbois (Jura), where we were staying for a time. The temperature of the wine cellars in which these barrels were stored was, on June 1st, 12·5° C. (54·5° F.); this rose gradually until September 1st, when it attained 18° C. (64·4° F.). In this cellar the brewery beer, brewed in the ordinary way, underwent change in the course of fifteen days or three weeks, whilst the beer brewed on the new system remained sound for several months. It is true that some of the barrels lost their frothiness, and that the beer in them underwent a peculiar vinous change, but these effects in no way depend on the conditions peculiar to the new process.
Comparing the beers K, M, T, of which we have been speaking, we see that, however useful the aeration and oxidation of the wort may be in quickening fermentation and facilitating clarification, yet it is by no means indispensable to the success of our operations that we should introduce into our worts large quantities of oxygen, whether by solution or combination. Beyond a certain limit—a limit which is undoubtedly overstepped in the existing process—oxygen is injurious to the palate characteristics and aroma of beer.
These comparisons have proved to us that the new process can be applied to wort aerated to the third of its saturate-capacity 394for oxygen, and pitched with a good “low” yeast, taken from the fermentation of a wort aerated in the same way, and that the beers thus obtained not only possess vastly superior keeping properties, but are equal in quality and superior in palate-fulness to beers brewed with the same wort on the existing system. We should be perfectly justified in forming this conclusion as to the strength[183] of the beer furnished by the new process, even if on tasting it we found that the new beer M was merely equal in strength to Tourtel’s beer brewed in the ordinary manner, since the wort in the new process, other conditions being the same, is weaker than the same wort treated in the usual way, from not having undergone that evaporation on the coolers which concentrates it. If we were to restore to the concentrated wort of ordinary brewing all the water lost by it through evaporation, the beer that we should obtain would be sensibly weakened.[184]
One thing, however, is that we must employ good varieties of “low” yeast. We have seen how the employment of certain forms of yeast renders the clarification of beers difficult, as well as extremely slow, and almost prevents their falling bright at the end of fermentation. These yeasts, moreover, frequently impart to beer a peculiar yeast-bitten flavour, which does not disappear even after a prolonged stay in cask. Even repeated growth of these yeasts, whether in closed or in open vessels, and no matter what quantity of air we may supply them with 395before fermentation, seems to have no effect in changing their character. The only thing we can do with these varieties of yeast is to get rid of them with all speed, and to replace them with others.
Notwithstanding the comparative success that has attended various trials of the new process on the commercial scale, that process has not yet been practically adopted: and here we must bear in mind that we have not to deal with any casual invention or mechanical improvement that could be introduced all at once into the working of a brewery; we are dealing with operations of considerable delicacy, which necessitate the adoption of a special plant to carry them out. Under such conditions time and labour are required to effect a change in the established processes of a great industry. This, however, cannot diminish the confidence that we have in the future of our process, and it is our hope that the same confidence will be shared in by all those who may give this work an attentive perusal.
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