Beer is the end product of the fermentation by yeast of sugars extracted from malted barley to produce alcohol. The contribution of malt and yeast to the quality of the final product is widely recognized but the flavour of the beer is heavily influenced by the mineral composition of the water and the hops used in its production. The real skill of the brewer is to get the combination of the different types of the four components correct.
For more information on malt, hops, yeast and water please see the "Ingredients" page by clicking here.
Most of the sugars used for the formation of alcohol in the fermentation process come from malt or, more correctly, malted barley. These sugars are present in the form of starch (in chemical terms starches are merely complex sugars) and are enclosed within the grain. The first step is the malting process (effectively this is the start of the fermentation process) where the grains are made to start germinating by soaking them in water in a warm environment. The germination process is halted before it can proceed too far by drying/heating the grain with hot air. At this stage the starches present in the grain have now been made available.
The next stage of the process is to mill the malt to produce relatively fine particles (called grist), which are for the most part starch. The grist produced from the milling process is mixed with hot water (called liquor) in a large vessel called the mash tun in carefully controlled proportions (normally around three parts water to one part malt). The water is held at 65° centigrade and the natural sugars present in the malt are extracted into the water to produce a sweetish liquid (called wort). This process is called mashing and usually takes 1-2 hours.
When all the sugars have been extracted, the wort is transferred into another vessel, called the copper. More water is added to the grist to ensure that all the sugars have been extracted in a washing process called sparging. This water is added to the copper and mixed with the original wort. Now the hops are added and the mixture is boiled, typically for a couple of hours. It is not usual practice to add all the hops at the beginning of the boil, some will be added at various stages throughout the boiling process and some will usually be added right at the end to give the final product the hoppy aroma that is typical of beer.
Next, the hopped wort is allowed to cool, usually in open troughs. Once cool the yeast is added (or pitched) to the wort, usually in the form of a slurry. The yeast converts the sugars present in the wort to alcohol and carbon dioxide (fermentation).
During this process the yeast will multiply maybe by as much as five times it's original volume and some of it will have to be removed.
Fermentation usually takes about 6-7 days during which time the wort is held at a temperature of 18 to 22° centigrade, after which the beer will be cooled. This liquid is then run into conditioning tanks where it is allowed to rest for a few days. Yeast held in suspension continues to convert sugar into alcohol during this time and the flavour will mature.
It is at this point that the production of a real ale differs from that of keg beers.
Originally in the early 1960s the big brewers looked at ways of "improving" beer production, storage and delivery. They developed the keg as a variation on the cask as it allowed them to:
Kegs were designed with straight sides unlike the traditional barrel or cask shape to allow for more efficient storing and also had a simple concave bottom. This allowed all the beer in the keg to be dispensed so the beer has to be filtered to remove all the solids such as yeast and hops which would otherwise block the line. A consequence of removing the yeast was that the beer was dead and Carbon Dioxide would not be generated. So, in order to serve the beer it has to be forced out with external gas.
To the big brewers this seemed like a "win-win" scenario, keg beer requires very little looking after so barmen needn't be skilled, it has a long shelf life and to be ready to drink as soon as it leaves the brewery. In order to achieve this as soon as the conditioning stage is complete the beer will be chilled and filtered to remove all the yeast and any hop fragments that remain in suspension. It is then pasteurised to make it sterile before being put into the keg.
All these processes affect the beer, removing flavours and aromas that were present in the beer and, in the case of pasteurisation, adding some that were not previously there. The process also removes the carbon dioxide naturally present in the beer. As this would lead to a flat, dull beer it is necessary to add extraneous carbon dioxide at pressure to give it some life, to create a head on pouring and also to allow it to be dispensed without using either a hand pump or gravity. This, however, adds a acidic "bite" to the beer that many find unpleasant. It also makes the beer gassy and leads to a bloated feeling after a couple of pints !
In order to try and eliminate the acidic "bite" breweries turned to a mix of carbon dioxide and nitrogen and called their beers "creamflow" or "smooth". This produces a more creamier, less fizzy beer with a big head but in the absence of the acidic "bite" it reveals that the product has become very bland. To get round this keg beer is served very cold to numb the taste buds.
Thus keg beer is dead and, while it has a longer shelf life and is more tolerant of poor handling the flavours do not mature.
Real Ale is not chilled, filtered or pasteurised at any stage in its production and the flavours will, therefore, continue to mature. Real Ale is put into containers called casks, traditionally these were wooden barrels but in the 1950s they were replaced by metal casks partly because of a shortage of skilled coopers but mainly because it was easier to sterilise the casks so the beer was less likely to go off. Metal casks also meant that air was less able to get into the cask ensuring that the beer would keep longer thus cutting down on wastage.
After filling the cask the brewer will usually add a small amount of sugar to encourage a secondary fermentation in the cask with the yeast that remains. Sometimes he will also add a small amount of hops, a process that is called dry hopping which is designed to give extra flavour and aroma to the beer.
Finings will also usually be added in order to get any solids present to drop to the bottom of the cask and leave the beer clear. The cask will then be sealed and is then ready to go to the pub.
So, Real Ale is a living product and the flavours will continue to mature while it remains in the cask. The downside is that this means that Real Ale is a limited shelf life. Real Ale therefore requires more looking after and both the brewer and the barman must have a higher standard of cleanliness. Poor standards of cleanliness in the pub are the main cause of the vinegary taste of a bad pint of Real Ale although there are other possibilities such as yeast infections.
When the cask arrives at the pub it is normally placed in a cellar or a special cool room (some pubs do keep their casks on the bar, usually with some form of cooling such as a water jacket). It is a myth that Real ale is served "warm" as the ideal temperature to serve Real Ale is 12 to 14° Centigrade. This is cooler than room temperature but not so cold as to numb the taste buds. If real ale is kept any warmer than this it loses its natural liveliness as the dissolved Carbon Dioxide comes out of solution. So the ideal pint of Real Ale should be cool (not cold), clear and with some gas (but not so much gas that it resembles coloured lemonade).
After the cask has been placed in the cellar most landlords will allow it to sit for anything up to a week. This allows the solids in the beer (hops, yeast etc.) time to settle out leaving a clear beer. It also allows the secondary fermentation to continue giving a fuller, more mature flavour. At this time a soft wood peg, called the spile, is put into the top of the barrel to allow the excess Carbon Dioxide generated by the fermentation process a way to escape and a tap will be placed in the bottom of the barrel to allow the beer to be drawn without disturbing the solids when it is ready.
Shelf life of Real Ale varies but, once the cask is opened, 2 weeks is normal. As a general rule of thumb the stronger the beer the longer it will keep.
The method of dispense that most people are familiar with is the handpump (this is more correctly called the beer engine) which is just a simple vacuum pump. Some pubs still set their barrels on the bar and serve into the glass directly by gravity. In the Midlands and the North of England electic pumps are common, these can look similar to keg taps but they nomally have a switch on them instead of a tap. In Scotland the traditional method of dispense is the tall fount which uses air pressure. All these methods are acceptable methods of serving real ale but the use of Carbon Dioxide or Carbon Dioxide gas mixes is not regardless of the pressure used.
Finally we come to the thorny question of the head. A pint of Real Ale can be served with or without a large head. Traditionally drinkers in the North of England and the Midlands like a large, "tight" head on their beer while those in the South of England do not. The head is achieved by the use of a "sparkler". This is a disc with very small holes in it like a shower head through which the beer is forced. Many drinkers are opposed to it on the basis that they feel it causes the loss of flavour and aroma. Others prefer their pint to have a thick, creamy head. Most real ale drinkers have a distinct preference and it is very difficult to get them to change their minds ! However, if you prefer your pint without a thick head any good landlord will remove the sparkler on request before pulling your pint if you ask.
At the end of the day this, hopefully, is what you will get.