EXAMINATION OF TWO SAMPLES OF OLD BOTTLED BEER
by A. Chaston Chapman, F.E.S. (1931)
In a Paper on the “Volatile Bye-products of Fermentation” which I contributed to the Institute (this Journ., 1897, 240), I included the analysis of three samples of old bottled beer. Of these, one was a sample of Bass’s beer, which had been for twenty years in bottle, another was a sample of beer brewed by Messrs. Mann, Crossman & Paulin, and the third was a sample brewed in the North of England, and which had at that time been in bottle for sixteen years. As I happened to have in my possession a bottle of the last mentioned of these three beers, I thought that it would be interesting to examine it again with the object of comparing the results with those obtained in 1897, this beer having now been in bottle for fifty-one years.
It had been kept throughout in a dark and fairly cool wine cellar, and the cork was found to be in good condition, and was withdrawn quite intact. The removal of the cork was carried out under such conditions as to avoid any possible infection of the contained beer, since it was intended to examine this for the presence of living yeasts and other organisms. Notwithstanding that the bottle had been stored on its side, a small quantity of the beer—possibly 20 cc.—had disappeared, presumably by passage through the cork, although the outer surface of the cork did not afford any evidence of this. It should be added that the cork was not waxed.
The beer possessed a very ethereal and vinous odour, and as judged by the palate was quite sound and free from acidity.
On analysis the following results were obtained, and for purposes of comparison I have given those of the corresponding numbers which were obtained in 1897 :—
From the above results it will be seen that there has been a very considerable increase in the proportion of esters, and that the volatile acidity has practically disappeared. There is also rather less alcohol, owing probably to a little evaporation through the cork. The furfural has, on the other hand, remained constant. The amount of the sample was too small to permit of an estimation of the higher alcohols, but, judging from my earlier results, this estimation is of comparatively little importance in reference to the changes taking place in beer during ageing.
The sediment when examined microscopically was found to consist mainly of yeast cells, the majority of which were spherical or ovoid, together, however, with a few which were distinctly elongated. All the cells had a shrunken appearance, the protoplasm seeming to have contracted and become detached from the cell walls, which were sharply marked. Two cells were frequently connected as in the budding process. The appearance of these cells was, in a good many cases, almost such as to suggest conjugation, but I think it more probable that budding had taken place, and that the connection between the two cells had become elongated and contracted in process of time. Below arc two photomicrographs showing the appearance of this sediment. In this connection it is interesting that Hopkins and Hunter (this Journ., 1928, 403) should have observed and called attention to precisely the same appearance in the case of a sample of beer which they examined, and which had also been in bottle for fifty years.
When a little of this sediment, removed with every precaution to prevent infection, was introduced into sterilised wort, rapid development of the cells occurred, and at the end of about a week the wort was in a state of vigorous fermentation. At the end of about two months some of the cells were found to contain structures which closely resembled spores. In the cases moreover, of growths on solid agar there was some evidence of speculation.
When examining the above sample I thought it might be of interest to examine a sample of the “King’s Ale” which was brewed in 1902, and of which I happened to have a bottle in my possession. The following results were obtained on analysis: —
The cork was quite sound, and the odour of the beer was pleasantly vinous. The flavour was full and strong, and there was no suggestion of excessive acidity. There was a good deal of dark brown sediment at the bottom of the bottle, and this, on microscopical examination, was found to consist almost entirely of amorphous protein particles, together with a good deal of hop resin. Very few yeasts were observed, and the appearance of the sediment in that respect was quite different from that of the sample above referred to. When, moreover, a small quantity of this sediment was introduced into sterilised wort, there was no growth, even at the end of two months. The beer, in fact, appears to have been practically sterile.
In these days of weak beers and rapid consumption it is pleasant to record that such strong ales were occasionally brewed in the past, and that they were capable of remaining sound and drinkable for over half-a-century.
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