Development on fine draft, the effect of a trace of yeast contained in a new beer in maintaining the fresh flavor of beer.

Takahashi, Y., Takahashi, S., Ujiie, F., Sakuma, S., Shimazu, T. and Kojima, K.

Abstract
The development of a method of stabilising beer against the oxidative processes which cause staling, by blending a small proportion of unfiltered, unpasteurised beer, which contains live yeast cells, into the main batch of sterile beer before packaging is described. Unlike traditional bottle conditioned or cask conditioned beers, which are packaged in a relatively "green" state and matured by secondary fermentation in the container from which they are dispensed, beer treated by this process does not undergo any significant change in composition as a result of the presence of yeast, as the beer is already so highly attenuated that little or no proliferation or fermentation can take place. The yeast cells remain alive, and stabilise the beer by taking up dissolved oxygen which would otherwise be likely to cause staling, but flavour is unaffected and no visible yeast precipitation takes place, so that the beer remains free from both haze and sediment. A brand of beer thus treated is now being produced by the Kirin Brewery of Tokyo, under the name of "Fine Draft".
Keywords : beer flavour stabilisation staling yeast