During the boiling a blend of English hops is carefully added. Boiling not only acts as an effective way of sterilising the wort but also extracts the bitter flavours and preservative properties from the hops. When the boiling process comes to an end, the wort is spun within the kettle to create a whirlpool which gently forms the protein and hop residue into a cone at the base of the vessel. The residue, called 'trub', is later discharged along with the 'spent grains' which are sold to farmers who use them as a highly nutritious cattle feed. The boiled hopped wort is passed through a cooler to reduce its temperature before being transferred to the fermentation vessels.
Yeast is added or 'pitched' into the wort in order to start fermentation.
Fermentation is a natural process which takes 3-4 days to complete. The yeast feeds upon the sugars in the wort converting them into alcohol. Heat is generated throughout the fermentation process and must be carefully controlled in order to protect the yeast. The yeast reproduces itself many times during fermentation and has to be regularly skimmed off the surface. When fermentation is complete, a quantity of yeast is extracted and retained in cold storage in readiness for future brews, whilst the excess is sent for use in the manufacture of health foods.