The Runcorn Brewery has a capacity of over 70,000 barrels/week representing about 100 brews. About 75% of production is lager and the remainder ale. Although in the initial brews wort composition was reasonably consistent, the clarity of wort from the Lauter Tun was often not satisfactory, hot breaks were poor and clarification from the kettle/hot wort centrifuge was not good. In addition brewhouse cycle times could not be reduced below 2 h 20 mins. Following investigations of various factors it was considered that the major faults were to be found in the milling and lautering phases. In the system used, both unmalted barley and malt are dropped from grain receivers into steeping vessels before wet milling. Initially the barley was steeped for 20 min at 50 degrees C but examination showed that the moisture content had reached 35% in this period and there was breakdown of the husk during milling. Reduction of the steeping time from 40 to 12 min and of the temperature from 50 to 15 degrees C resulted in grain moisture contents being reduced to 25%. By lowering the speed of the top rolls of the mill from 530 to 370 rpm and of the bottom rolls from 600 to 420 rpm there was less damage to the husk during milling, mill rates were increased to their rated capacity, replacement of rolls due to wear was greatly reduced from < 500 h to > 750 h and brewhouse extracts were increased considerably. With these changes in milling, lautering performance improved dramatically without necessary change in its own operation. Run off rates were increased and clear worts were obtained. In addition a slightly sulphurous flavour which appeared in the beers from the early brews was eliminated.
Keywords: brewhouse brewing lautering mashing milling wort boiling