Brewing Operations
The first operation in commercial brewing is the milling of the malted barley. As with drying hops, and malting the barley, skill is required if the best results are to be obtained. The malted barley is milled so that it is hardly more than cracked. From the mill the malted crushed barley or ‘grist’ is conveyed to the mash tuns (our mash tun will be a two-gallon polythene pail, as we shall see later on). The mash tuns of the brewery are enormous copperdomed vessels, often holding many thousands of gallons. It is in these that the first great changes take place. The malt is fed into these and mixed with water - from now on called ‘liquor’ simply because in the brewery there is no such thing as water except the stuff they wash the floors with. Brewery liquor, then, and malt form the wort in the mash tun. This is brought to and maintained at a temperature suited to the particular enzyme whose action is required to take place first. It is then increased and increased again until the brewer is satisfied that the changes brought about by the various enzymes are complete. At this stage the wort is boiled. As soon as the malt is put in the mash tun and wetted, the process halted in the malting kiln recommences. Starch is converted to sugars by digestive ferments or by the enzyme action just mentioned. Temperature control during this stage is essential because certain enzymes work - bring about their changes - at temperatures that would destroy others. U nderheating would merely leave certain enzymes inactive so that the desired changes would not take place - or only partly take place. Complete change by enzyme action is necessary if good beers are to be produced.
Conversion, and extraction of flavors and other essentials taking place in the mash tun take from four to six or even eight hours. When the wort has been run off the near-spent grain into the coppers for boiling, more hot brewery liquor (not water) is sprayed over the grain until the brewer is satisfied that he has obtained all the goodness he can get.
Next comes boiling. From the mash tuns the wort is run into coppers and boiled with hops. It is during this boiling that the character of the beer is ‘fixed’ - or decided - and the enzymes which bring about the desired changes in the mash tun are destroyed. If they were not destroyed they would merely continue the process of convertion until the wort became a tasteless and unpalatable mixture of brewery liquor, spent hops flavor and alcohol. Boiling is necessary not only to halt the enzyme action but also to destroy wild yeasts and bacteria by sterilizing. Wild yeasts and bacteria cause spoilage ferments.
After boiling, the wort is cooled by refrigerating machinery to about 60°f. At this stage yeast is ‘pitched’ into the wort; and now the great transformation from murky, flat wort to bright, foaming beer begins. This is known as fermentation, the action of which is described under ACTION OF YEAST.
A few hops are added during the latter stages of fermentation to add extra tang and preservative properties - some of these having been lost during boiling.