Wort clarification

As the beer progresses through the brewery it comes into contact with vessel surfaces, pipes, and fittings, all of which can harbor infection, particularly on the cold side of the brewery after wort clarification. Any surface that comes into contact with wort, beer, or yeast should be thoroughly cleaned and sterilized, that is, vessels, piping. 

High gravity worts do not give such rapid clarification as worts of lower extract because the difference between the density of particles and the wort is less (Stokes Law). If no hop material is present, separation is poorer and the best result has been claimed for hop powder [26]. Additions of Irish Moss, polyvinylpyrrolidone, nylon 66 and particularly bentonite, have been stated to improve separation [26]. Anaerobic conditions are also said to increase the amount of material deposited, particularly by injecting carbon dioxide into the wort line when pumping into the whirlpool tank [26]. 

Self-cleaning clarifiers, in which the solids are discharged at intervals while the centrifuge is operating at full-speed (Fig. 20.12). They are available for both wort and beer clarification with throughputs of up to 600 hl/hr (370 brl/hr). The same machines used for beer recovery from fermenters and tank bottoms operate at up to 40 hl/hr (25 brl/hr). Many of these machines used for beer treatment are hermetically sealed so that neither carbon dioxide is lost nor oxygen taken up. 

In breweries, for example, hermetic centrifuges can be used for pre-clarification of beer ready for packing, with no carbon dioxide losses and no destruction of protein for the clarification of the cold wort, with a good clarification efficiency because protein particles are not destroyed. In dairies, hermetic centrifuges are used because milk is sensitive to both oxidation and shear. 

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