GB1060722A - An improved process for the fermentation of brewers wort - Google Patents

Abstract

An accelerated batch process for fermenting brewers' wort with yeast includes the steps of providing in a fermenter vessel a fill of oxygenated wort which contains a high concentration of yeast at the start of fermentation, controllably and gently agitating the mixture to an extent sufficient to secure and maintain a finely divided and substantially uniformly distributed suspension of yeast in and throughout the wort during the greater part of the fermentation period, whereby the rate of fermentation exceeds that of traditional batch brewing, permitting fermentation to proceed under controlled conditions of temperature within the range 40 DEG to 75 DEG F. and under controlled conditions of agitation until the desired degree of attenuation has been substantially achieved, and arresting the agitation and separating beer from yeast, wherein the amount of yeast grown during the shortened period of fermentation (by comparison with that of the traditional batch process) is substantially the same as would have been grown when fermenting the same amount and composition of wort with the lesser amount of the same yeast at the same temperature in the traditional manner and the control of yeast growth is exercised principally by the adjustment of the oxygen content of the wort at the time of filling the vessel. Thus, prior to fermenting the wort may be saturated with air or treated with oxygen (5% by volume) injected during 3 hours. After the fermentation either the fermentation vessel is emptied completely and yeast is separated from the beer outside the vessel, or the yeast is permitted to settle in the vessel after which beer is drawn off through a stand-pipe. In either case such yeast may be employed to pitch a further batch of wort. The batch fermentation may be carried out in cycles employing a single fermentation vessel or several such vessels operating at staggered time intervals, for example a series of five vessels of which one is taken out of service for washing, cleaning and sterilizing after every fourth fermentation cycle. Fermentation is conducted at regulated temperatures under enclosed conditions at atmospheric pressure and the requisite agitation is produced mechanically or by the circulation of carbon dioxide (or nitrogen) through the wort. The first heads together with extraneous amorphous matter are removed by suction or by mechanical skimming after their formation in the initial stages of the fermentation. Highly flocculent strains of yeast (specified) may be employed. The high concentration of yeast when pitching any vessel, which should be at least 75% of, and preferably is equal to or in the excess of, the maximum yeast concentration (specified) normally achieved during traditional batch fermentation of brewers' wort, lies within the range 10-60 grams per litre, preferably 10-25 grams per litre. The oxygen content of fresh wort should lie within the range 3-150 milligrams per litre. Operational examples of the brewing of ale, lager, stout and porter are disclosed.