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How Beer is Brewed

So You Want to be a Beer Expert?

Brewing is a magical process, presided over by magicians. Anyone who can take simple ingredients such as grains of barley, hop flowers and water and turn them into such a beguiling product as beer is clearly someone special.

It’s hard to do justice to the skills of a brewer when prosaically describing the brewing process but it’s useful to set out, in basic terms, how beer is made, so that at least there’s some explanation of how the various flavours described in this book arrive in your glass.

Malt and Mash
FarsonsThe process of brewing begins with malt. Malt is barley grain that has been partially germinated to help release starches and enzymes needed for the brewing process and then kilned to prevent further germination.

The degree of kilning also dictates the character of the malt; the more ‘baked’ the malt, the darker the colour and the more roasted the taste. Some malts are toasted dark for bitter, coffeeish flavours; others are just lightly crisped for a sweeter, nuttier taste.

At the brewery, the malt is crushed and then combined in a vessel called a mash tun with hot water (known as ‘liquor’ in the trade), which has usually been treated to adjust its chemical balance.

At lager breweries a mash converter is generally used instead of a mash tun. This may be part of a decoction system, which involves pumping part of the liquid to and from a separate vessel and exposing it to a higher temperature in an effort to extract the starches and enzymes from the malt, which is not as refined as that used in ale production.

Hopping Aboard
In both ale and lager processes, the result is a thick, sugary liquid called wort. This is run off from the mash tun and diverted into a boiler known as a copper. Here the wort is boiled up with hops, which add bitterness and sometimes herbal, spicy, citrus or floral characters.

Like malts, hops come in many varieties. Some are very bitter; others milder. Some make themselves known in the aroma; others are expressed in the taste. Hops also act as a preservative.

They can be added as whole hop flowers or as compressed pellets. Some brewers use hop oils (concentrated extract), but these can be astringent. The hops are added at various stages of the boil.

Fermentation Time
After an hour or two in the copper, the hops are strained out and the wort is run off and cooled, before being pumped into a fermenting vessel, where yeast is added (‘pitched’).

Cains BreweryYeast is a single-celled fungus that turns the sugars in the wort into alcohol and carbon dioxide (the gas that gives beer its natural effervescence). Each yeast, however, also has its own character, which is harnessed and preserved by brewery chemists. Many breweries use the same yeast for decades.

During the first few days of ale fermentation, the yeast works furiously with the wort, growing quickly and covering the top with a thick, bubbly layer of foam (hence ales are also known as 'top-fermenting beers'). Most is skimmed off, but some sinks into the brew and continues to work, eating up the sugars and generating more carbon dioxide and alcohol.

Lager beers are known as ‘bottom fermenting’, because the yeast they use sinks to the bottom of the wort, rather than lying on the top. They also ferment at a lower temperature than ale.

A few days later, this ‘primary fermentation’ is deemed over. Ales may then be transferred to a conditioning tank, where the yeast continues to round off the rough edges before the beer is ready for packaging.

Lagers, ideally, should be transferred to a lagering tank where the beer will sit for weeks, perhaps months, at near-freezing temperatures to bring the beer slowly to crisp, clean perfection.

Ready for Sale
The next stage of the brewing process depends on the sort of packaging the beer requires. If ale is to be sold as a living product, it is racked into casks where yeast continues to ripen and mature the beer right up to the point of sale. This produces ‘cask-conditioned’ beer, or ‘real ale’.

A similar process is employed to produce ‘bottle-conditioned’ beer, or ‘real ale in a bottle’, which, like the draught equivalent, contains living yeast and needs to be poured with a little caution to prevent this sediment from entering the glass.

Lagers tend to be filtered, or at least drawn off their yeast. If sold locally, in places like Germany and the Czech Republic, they may be served without being pasteurised.

Most bottled beers – ales and lagers – are filtered and many, regrettably, are pasteurised, too, which can spoil the flavour, especially if the beer is delicate or light-coloured.

Bottled beers that are ‘sterile filtered’, but not pasteurised, are fresher-tasting than pasteurised beers, but they do not acquire the complexity of bottle-conditioned beers.

Filtered and often pasteurised draught beers are known as ‘keg beers’ or ‘nitrokeg beers’, depending on which gas is used to pump them to the bar.

Intrigued? A much more comprehensive account of the brewing process and a full guide to beer appreciation can be found in Jeff's So You Want to Be a Beer Expert?

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