MAKING OF BEER
Pure water is an essential ingredient in good beer and brewers pay scrupulous attention to the source and purification of their brewing water. The water used in brewing is purified to rigidly-set standards. If it does not have the proper calcium or acidic content for maximum activity of the enzymes in the mash, it must be brought up to that standard.
Barley is used to make brewers' malt. At the malting companies, barley is soaked, germinated (sprouted), then dried and/or kilned/roasted to arrest further growth. During the period of controlled growth in the malting plant, specific barley enzymes are released to break down the membranes of the starch cells that make up most of the kernel. But these are internal changes only; apart from a slight change in colour, the external characteristics remain essentially unchanged. When the malt leaves a malting plant, it still looks like barley.
In the brewery, the malt is screened and crushed rather than ground to flour in order to keep the husks as whole as possible. This process not only prevents the extraction of undesirable materials from the husks but also allows them to act as a filter bed for separation of the liquid extract formed during mashing.
Malt is added to heated, purified water and, through a carefully controlled time and temperature process, the malt enzymes break down the starch to sugar and the complex proteins of the malt to simpler nitrogen compounds. Mashing takes place in a large, round tank called a "mash mixer" or "mash tun" and requires careful temperature control. At this point, depending on the type of beer desired, the malt is supplemented by starch from other cereals such as corn, wheat or rice.
The mash is transferred to a straining (or lautering) vessel which is usually cylindrical with a slotted false bottom two to five centimetres above the true bottom. The liquid extract drains through the false bottom and is run off to the brew kettle. This extract, a sugar solution, is called "wort" but it is not yet beer. Water is "sparged" (or sprayed) though the grains to wash out as much of the extract as possible. The "spent grains" are removed and sold as cattle feed.
5.Boiling and Hopping
The brew kettle, a huge cauldron holding from 70 to 1,000 hectolitres and made of shiny copper or stainless steel, is probably the most striking sight in a brewery. It is fitted with coils or a jacketed bottom for steam heating and is designed to boil the wort under carefully-controlled conditions. Boiling, which usually lasts about two hours, serves to concentrate the wort to a desired specific gravity, to sterilize it and to obtain the desired extract from the hops. The hop resins contribute flavour, aroma and bitterness to the brew. Once the hops have flavoured the brew, they are removed. When applicable, highly-fermentable syrup may be added to the kettle. Undesirable protein substances that have survived the journey from the mash mixer are coagulated, leaving the wort clear.
6. Hop Separation and Cooling
After the beer has taken on the flavour of the hops, the wort then proceeds to the "hot wort tank". It is then cooled, usually in a simple-looking apparatus called a "plate cooler". As the wort and a coolant flow past each other on opposite sides of stainless steel plates, the temperature of the wort drops from boiling to about 10 to 15.5 °C, a drop of more than 65.6 °C, in a few seconds.
The wort is then moved to the fermenting vessels and yeast, the guarded central mystery of ancient brewer's art, is added. It is the yeast, which is a living, single-cell fungi, that breaks down the sugar in the wort to carbon dioxide and alcohol. It also adds many beer-flavouring components. There are many kinds of yeasts, but those used in making beer belong to the genus saccharomyces. The brewer uses two species of this genus. One yeast type, which rises to the top of the liquid at the completion of the fermentation process, is used in brewing ale and stout. The other, which drops to the bottom of the brewing vessel, is used in brewing lager.
In all modern breweries, elaborate precautions are taken to ensure that the yeast remains pure and unchanged. Through the use of pure yeast culture plants, a particular beer flavour can be maintained year after year. During fermentation, which lasts about seven to 10 days, the yeast may multiply six-fold and in the open-tank fermenters used for brewing ale, a creamy, frothy head may be seen on top of the brew. When the fermentation is complete, the yeast is removed. Now, for the first time ,the liquid is called beer.
For one to three weeks, the beer is stored cold and then filtered once or twice before it is ready for bottling or "racking" into kegs.
In the bottle shop of a brewery, returned empty bottles go through washers in which they receive a thorough cleaning. After washing, the bottles are inspected electronically and visually and pass on to the rotary filler. Some of these machines can fill up to 1,200 bottles per minute. A "crowning" machine, integrated with the filler, places caps on the bottles. The filled bottles may then pass through a "tunnel pasteurizer" (often 23 metres from end to end and able to hold 15,000 bottles) where the temperature of the beer is raised about 60 °C. for a sufficient length of time to provide biological stability, then cooled to room temperature.
Emerging from the pasteurizer, the bottles are inspected, labelled, placed in boxes, stacked on pallets and carried by lift truck to the warehousing areas to await shipment. Also in the bottle shop may be the canning lines, where beer is packaged in cans for shipment. Packaged beer may be heat-pasteurized or micro-filtered, providing a shelf-life of up to six months when properly stored. Draught beer, since it is normally sold and consumed within a few weeks, may not go through this process. The draught beer is placed in sterilized kegs ready for shipment.