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 The wort passes from the Mash Tun to the copper or kettle where hops and sugar are added. The contents of the copper are boiled for 1-2 hours in order to sterilise the wort, develop flavour, coagulate proteins, adjust the gravity of the wort and to destroy the enzyme Diastase. Wort is run off from the copper into the hop back. Spent hops and protein sink to the bottom and are retained when the hop back is emptied. They are used in the manufacture of fertilisers. The wort is cooled in a cooler to about 15.6C (60F). This is lower for lagers. Oxygen may be infused to aid yeast activity.
The wort is run into the fermenting vessels.
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Malt is lightly crushed in a mill. It is now known as grist and passes to the grist case. Other cereals may be added in the grist case
The liquor is brought to the correct temperature. The Mash Tun, a circular vessel of cast iron or stainless steel, has been warmed. Grist and liquor are run through a mixing device known as an external masher. The mixture (‘goods’) is left to infuse for about 2 hours at 65.6C (150F). The malt solution (Wort) is run off from the bottom of the Mash Tun. Hot liquor is sprayed on the goods. This process is known as sparging. Spent grains are removed and used to manufacture animal foodstuffs.
Fermentation converts sugars into alcohol and Carbon Dioxide. Yeast is added to the wort in the fermenting vessels and mixed vigourously. Fermentation takes about 3-4 days (longer for lager) About 12 hours after the yeast is added, a head starts to form. The rise in temperature is regulated and checks are made of the gravity at intervals. Additional aeration may be necessary.