From The Brewers’ Journal – January 1918
While the yeasty taste of some beers is due to degeneration of the yeast through warm fermentation and storage, this is not always the reason.
This opinion is based on the fact that, of two beers – one a 10 to 11 per cent lager beer and the other a 6 per cent light beer – made in the same brewery, the former, fermented and matured at a low temperature, had a flavor, whilst the latter, prepared without artificial cooling, tasted of the yeast, though the wort was always pitched with fresh lager-beer yeast grown in the stronger medium. He attributes the cause to the warmer temperature and lighter hopping; and mentions that the same flavor has been found in beers from 10 per cent wort when the fermentation was conducted with bottom yeast, but under top-fermentation.
Dark beers seem to be more susceptible than pale. Worts from malt low in proteins are a cause of yeast degeneration, and such worts are furnished by 1916 barleys, in strong contrast to those of the previous year, which were particularly suitable for brewing light beers. For this purpose, the higher yield obtained from the present malts is counteracted by the loss of quality sustained when the worts are unduly thinned in sparging. There is then a tendency to sluggish secondary fermentation, and if an attempt be made to remedy this by employing a higher fermentation temperature, then the risk of yeasty tasted is incurred.
A higher pitching temperature does no harm in this respect, and the same applies to the curly head stage, after which, however, cooling is essential, so that the beer has attained proper cellar temperature by the time it is ready for racking. With malts higher in protein, on the other hand, thin worts mostly contain sufficient nitrogen to keep the yeast active at low temperatures and give ample attenuation.
With regard to a proposal to brew 10 to 11 per cent beers and dilute them, to the required gravity, with boiled water at the end of the primary fermentation, this will not be suitable in all cases; but the point is considered worthy of being followed up, in view of the numerous complaints of yeast degeneration and consequently spoiled flavor.
A good plan to ensure more active fermentation is that practiced in top-fermentation brewing, namely, to allow the yeast to act on a small quantity of the wort at about 68 deg. F., and rouse it well, before pitching the bulk of the wort, this method having proved very successful during the present season. Circulating the wort in the fermentation vessel by means of the pump is also a good measure, and finally the beer should be well hopped to give a good aromatic flavor, stimulate fermentation and improve the head retention of the beer. (as published in Wochenschrift für Brauerei)
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