Talking Tech

Pumping beer – from cellar to glass

One thing that is guaranteed to set the lifelong cask ale drinker’s alarm bells ringing is when the bar server pulling their pint of cask tells them – “oh, I’ll just have to go and change the gas”. Having spent all their drinking lives believing that cask ale is unsullied by dreaded CO2, a pub that requires gas to serve their cask ales is surely up to no good?

Well usually, they aren’t, it’s just part of the modern pub cellar. In this piece, we’ll look at how your cask ale gets from the pub cellar to the bar.

The first thing to remember is that not all pubs are the same. How the beer gets to the pump in somewhere like Manchester Arndale’s Micro Bar is going to be very different from its route from one of the three cellars in JD Wetherspoon’s Moon Under Water.

While pins of Old Tom have seasonally appeared on the bar of Robinsons’ pubs, the recent growth of the ‘micro-pub’ has seen a revival of this most traditional method of serving – your beer poured directly from a cask. Micro-pubs like Stalybridge’s Bridge Beers have their casks on display on a rack behind the bar and use nothing more than gravity to fill your glass.

In the 70s, cask ales were regularly served by metered electric pumps but since the 1980s, the bar mounted handpump has become synonymous with cask ale.

The simple syphon pump, also known as a beer engine, was first patented in 1691 by a Dutch inventor called John Lofting. The principle of operation is simple – an airtight chamber sits between the line from the cask and the pump’s nozzle. A piston in the chamber is connected to the pump’s handle. When the server pulls the handle, the piston is pulled up, drawing beer into the chamber via a one-way valve. When the handle is returned, another one-way valve allows the beer to pass through the piston. On the next pull, the beer is pushed out of the chamber and through the nozzle while more beer is pulled into the chamber.

©John O’Donnell

As beer may be sat in the cylinder for some time between pulls, pumps are typically fitted with a cooling system which circulates chilled water through a jacket surrounding the cylinder.

The amount of beer dispensed on each pull can be a quarter, a third or half a pint. The larger the volume dispensed with each pull, the larger the effort required. With casks located in a traditional cellar, the beer engine must create enough suction to lift the beer from the cask. It must also overcome the natural resistance to flow of the beer line – the longer the line, the more effort required.

Flojet pump (©John O’Donnell)

Where the length of line and/or height between cellar and bar is too long, the handpump must be assisted with an additional pump in the pub cellar. While electric pumps can be used, the most common type of pump is a gas driven diaphragm pump – usually known as a Flojet pump, the trade name of the most commonly seen model.

In a diaphragm pump, two flexible diaphragms oscillate back and forth, creating chambers which suck in and then push out the beer. The diaphragms are connected by a shaft so as one sucks, the other pushes. The movement of the diaphragms is driven by compressed gas which does not come into contact with the beer.

On the first stroke, the gas moves one diaphragm to push beer from the first chamber via a one-way ball valve. At the same time, the second diaphragm is sucking beer into a second chamber. At the end of the stroke, the gas flow is diverted to push the second diaphragm, pushing out the beer drawn in on the previous stroke, while more beer is drawn into the first chamber. The cycle then repeats.

©John O’Donnell

Flojet pumps allow pubs to serve cask ale from cellars some distance from the bar and allow smaller diameter lines to be used, reducing the amount of beer in the lines at any given time. As they reduce the effort required to operate handpumps and reduce wear on the pump seals, they are regularly fitted in lines even where they aren’t strictly necessary.

Although electric powered flojet pumps are available, as pub cellars usually have a ready supply of gas, the gas-powered models are the most common – which leads to that unfortunate situation where the gas running out does stop cask ale flowing.

The Flojet is also the secret behind cask ale service from back bar taps such as those seen at the The Oast House and Stubborn Mule’s tap room. When the tap is opened, the flojet sets to work pumping the beer through the tap. They can easily generate enough pressure to force beer through a cask sparkler.

Talking Tech – Caring for cask in the pub cellar

Earlier this year, we looked at the efforts brewers go to ensure the beer in their casks has enough dissolved carbon dioxide to allow pubs to serve it with the gentle carbonation associated with the format (see here). In this issue, we look at what happens when that cask reaches the pub cellar.

Pubs may buy their beer direct from their local brewers, they may have to source it from their Pub Company landlords, or they may purchase it from a beer wholesaler who supplies beers from many breweries. We will look at how these supply arrangements work in a future issue but the result is that casks may arrive at the pub direct from a brewery a mile away or via a lengthy supply chain.

Cooling the beer to cellar temperature

Once casks are delivered into the care of a pub’s cellar team, the first thing they need to do is give them time to adjust to cellar temperature.

In an ideal world, to keep beer at its very best, it would be stored in temperature-controlled warehouses and delivered to the pub in refrigerated vans. However, such ‘total cold chain’ distribution is rare in the UK. Although casks from a local brewery may have only come out of a cold store a couple of hours earlier, those from further afield may have had a lengthy journey and casks may arrive at the pub at ambient temperature. If a cask is delivered at 20°C and placed in a cellar at recommended cellar temperature of 12 °C , it will take the beer inside the cask over 24 hours to cool to 12°C.

Cleanliness

Pub cellars should be meticulously clean places, especially when keeping cask ales which are open to the atmosphere and whatever airborne bacteria it contains. Food has no place in the cellar with dairy products a particular risk – lactobacillus, the natural bacteria which turns milk into yoghurt or cottage cheese, is one of only a few bacteria that is equally at home in beer, but its sour flavours are not usually welcome in your best bitter.

Spillages should be mopped up at once – open beer puddles are the chief route for the spread of wild yeast and bacterial infections. Cellar walls and ceilings should be painted with anti-fungal paint and washed down frequently.

Give it time…

Cask ale needs time to mature and condition (commonly called ‘secondary fermentation’) after it is racked into casks – this is typically anywhere from a week for a simple pale ale to a month or more for a stronger more complex ale. Beer which has not had time to mature will be what is known as ‘green’ – containing off flavours which can mask the true flavour of the beer.

Traditionally, casks would complete most or all of their maturation in the pub cellar, However, many brewers are aware that modern cellars tend to be smaller than those of old and publicans don’t have the space to hold beer for extended periods.

Therefore increasingly brewers will complete most of the conditioning at the brewery – either in tanks before racking or by holding newly racked casks at the brewery before being delivered to customers. However, some brewers still retain traditional methods and will expect pubs to hold casks in the cellar for a week or more before preparing them to be put on sale.

Some pubs have the good fortune to have large cellars where they can routinely have their beers delivered two or more weeks before they expect to need them. Casks rarely indicate how long the beer has been in the cask (more commonly being marked with a best before date rather than a racking date). Therefore the less fortunate cellarman needs to know how his or her chosen brewers condition their beers – only with that knowledge can they rotate the beers in their cellar to ensure those that need time are allowed it.

Preparing for service

Cask ales contain live yeast so to prepare a cask for service, it needs to be placed in its final serving position (be this on its side on a traditional stillage or on its end for modern ‘vertical extract’) to allow the yeast to drop out of the beer before serving. See our earlier piece on casks and kegs for a brief explanation of vertical extraction.

A beer that has been largely conditioned in the brewery can ‘drop bright’ in as little as a few hours, whereas a more traditionally conditioned ale may need 48 hours or more. While some unfined beers may be intentionally hazy, most will still clear in some form or other given time.

Venting

An unvented plastic shive

Venting is the process where the seal on the cask (which may be wooden but is now more commonly plastic) is breached to release the pressure which has built up during secondary fermentation. Traditionally the cask is vented through the ‘shive’ – the seal on the hole in the side of the cask where the cask is filled – but with modern vertical extraction, the cask is vented through the ‘keystone’ (in the round end face of the cask) through which beer will also be drawn out.

The purpose of venting is two-fold. Firstly, it allows excess carbon dioxide (CO2) to slowly bubble out of solution until an equilibrium is reached where each pint of beer will contain just over one pint of CO2 dissolved in it – this level of around 1.1 ‘volumes’ of CO2 is the gentle carbonation level associated with good cask ale.

However, the second purpose is to allow purging of volatile substances such as acetaldehyde (green apples flavour) which are generated during fermentation.

Venting must always be delayed until the cask has reached cellar temperature. With the volume of CO2 beer can hold in solution being related to its temperature, to vent a warm beer will result in loss of much of the hard earned ‘condition’. If dissolved CO2 escapes when a beer is warm, it cannot be regained when the beer later reaches cellar temperature.

Vented cask with soft spile

After venting, the cellarman may initially insert a porous soft peg (‘spile’), allowing a lively beer actively generating carbon dioxide (CO2) to breathe – allowing CO2 to escape and reach that soft carbonation level we seek out.
Alternatively, they may go straight to inserting a semi-porous hard-spile, allowing the beer to continue to develop while keeping its condition until the beer is needed.

Even with a hard spile inserted, a cask which has completed secondary fermentation will still slowly loose condition through the spile. There is no hard and fast rule on how long a cask can be kept on hard spile but more than three or four days would be excessive.

The cellarman’s art

Which leads us to the final, but perhaps most important skill of the cellarman – that of timing their own art.

A beer festival knows exactly when their casks are expected to be ready (even if the live nature of beer and the tight timescales they often work in means they can’t always get it exactly right).

By contrast, the pub cellarman can be juggling the maturation and venting of multiple casks, trying to get each to perfect condition at just the time the preceding cask is emptied by their thirsty customers.

With the variety of factors that affect how busy or pubs are – from TV events to the vagaries of the British weather – meaning that casks can sell out in anything from 2 to 72 hours or more, this is no mean task.

When you get that perfect pint – remember the skill that has been involved in getting it there.

Talking Tech – Making Gluten Free Beer

In its basic form, beer is made from water, yeast, hops and malted barley. And malted barley naturally contains gluten – a family of proteins which help foods maintain their shape.

Approximately 1% of the UK’s population suffer from Coeliac disease – a serious autoimmune disease where the body’s immune system attacks itself when gluten is eaten. Another 6% report an allergy or intolerance to gluten. So does this mean that they are denied the pleasure of good beer?

Photo: CAMRA

Thankfully not. Malted barley and wheat are used in brewing to provide the sugars that the yeast feeds on to produce alcohol, but they are not the only cereals which can be malted. While other common brewing adjuncts rye and oats do contain gluten, there are alternatives including sorghum, millet, quinoa, buckwheat, rice and maize which do not. 

Manchester based Green’s launched what they claim was the UK’s first naturally gluten free beer, Discovery Ale, in May 2004 (although the beer itself is brewed in Belgium). The beer was the result of years of research by gluten intolerant founder Derek Green, eventually teaming up with a Belgian professor who had a gluten intolerant daughter. Made with a combination of buckwheat, millet, sorghum, hops and brown rice, Discovery was followed by a naturally gluten free India Pale Ale and a dry hopped lager which are exported around the world.

The difficulty for those brewing with alternative grains is that as well as providing sugars, barley and other gluten containing cereals also impart much of the flavours and body associated with modern beers. Sorghum can tend to add too much sweetness to a beer and attempts to compensate for barley and rye flavours often lead to an unbalanced beer. Therefore, brewers like Greens need to work harder to match the flavour of traditional beer.

However, brewing with alternative grains is not the only way to produce ‘gluten free’ beers. In the UK and Europe, for a food stuff to be labelled ‘Gluten Free’ it must contain less than 20 parts per million (20ppm) of gluten. To take advantage of this, the brewing industry has developed special enzymes which break down the gluten proteins during fermentation of the beer. These have allowed brewers to produce beers using traditional ingredients and methods, but which contain extremely low levels of gluten in the finished product.

One such commonly used additive is ‘Brewers Clarex’ also known as ‘Clarity’, which is added to chilled wort at the start of fermentation. Clarex was originally developed to remove proteins from beer that could cause ‘chill haze’ and help brewers produce clearer beer. It was already widely in use before it was discovered that it also had the effect of breaking down the structure of gluten. 

Pioneers in this new technique included Green’s, along with Yorkshire’s Wold Top and Hambleton Ales and Cumbrian brewery Stringers. They have since been joined by a whole host of brewers across the country, some who have added one or two gluten free beers in their range, others whose entire production is gluten-free.

One local brewery in the latter category is Salford’s First Chop who have a full range of gluten free beer available in cans, bottles, kegs and cask. The proudly boast that all beers are tested to show a gluten content less than 5ppm. All their beers are also suitable for vegetarians.

Brightside Brewery, based in Radcliffe, use Clarex on all their beers which go into bottle, can and kegs (including sub-brand Wildside). Sales director Carley Friedrich explained to Beer Buzz that in order to be able to label their beers as gluten free, a sample of each brew has to be sent to an independent laboratory for testing. They must pay for this test and wait four days for the results to come back before they can release each batch. Thankfully, they’ve never had a brew fail the test. 

Wildside Gluten Free beer in cans. (Photo: Brightside Brewery)

Carley told Beer Buzz that Brightside saw the introduction of gluten free beers as a sales opportunity having noticed an increasing interest in gluten free products. Some 8.5 million people in the UK are now believed to be following a gluten free or gluten reduced lifestyle, the majority by choice rather than on medical grounds so it was a timely move on Brightside’s part.

Another local brewer who has made all production gluten free is Green Mill, based at the Harewood Arms pub in Broadbottom, Tameside. Brewer Mat Wild told Beer Buzz that they brewed their first GF beer two years ago when a gluten intolerant customer at the pub made them realise there are plenty of ale lovers out there who were being denied a choice of ales. Their full range of beers has been Gluten Free since early 2018. 

Other entrants into the gluten free market include Magic Rock’s Fantasma – a juicy 6.5% IPA available in can and keg and Origin, a 5.7% IPA from Leeds’ Northern Monk. 

Processing beers to remove gluten isn’t the answer for everyone though. Although 20ppm is accepted as a safe level for most gluten intolerant people, some coeliacs are sensitive to the small levels of gluten in such beers. In UK and European legislation, no distinction is made between products which have been made without any gluten containing ingredients and those which have been processed to remove or reduce gluten – as long as they have <20ppm they can be labelled Gluten Free.

However, this is not the case in the USA, Canada, Australia or New Zealand. In the USA only beers made from gluten free ingredients can be labelled ‘gluten free’. Beers processed to remove gluten can only be labelled ‘gluten removed’ or ‘gluten reduced’. The US market also recognises “dedicated gluten free beer’ – this is beer made in a brewery which only produces gluten free beer and where there is therefore no risk of cross contamination.

Campaigners in the UK argue that the current rules in the UK fail those whose conditions requires them to avoid all trace of gluten, meaning they can’t rely on labelling to find naturally gluten free beers. There are also those that claim to industry standard test for gluten in beers (known as the R5 Competitive ELISA test – the latter an acronym for enzyme-linked immunosorbent assay) can show beers as gluten free which still contain the antigens which celiacs respond to.

The result of these concerns is a growing call from more naturally gluten free products. One relatively recent addition to the choice available is Steel Cut, a 4.5% naturally gluten free golden ale made with oats, buckwheat, maize and sorghum by Suffolk’s Burnt Mill brewery. It was developed after head brewer Sophie de Ronde discovered that she is gluten intolerant. 

Science is also seeking to give yet another option for sufferers with the development of gluten free barleys. Australia’s Commonwealth Scientific and Industrial Research Organisation (CSIRO) has developed a barley called Kebari™ which has 10,000 less gluten than regular barley – around 5ppm. Edinburgh’s Bellfield Brewery has been running trials using the barley since 2016. 


The internet is a great source of information for Coeliacs and other gluten intolerance drinkers. There is a support group on facebook at https://www.facebook.com/groups/Beers4Coeliacs

Charity Coeliac UK offers a food and drink directory to members listing gluten free beers on their website https://www.coeliac.org.uk

Other useful sources include:

https://www.allergy-insight.com/free-from-food/gluten-free/gluten-barley-and-wheat-free-beer/

glutenfreepassport.com/pages/gluten-free-beer-around-the-world

Local brewers producing gluten free beers:

www.firstchop.co.uk

brightsidebrewing.co.uk/

greenmillbrewery.com/

www.glutenfreebeers.co.uk/

Talking Tech – The battle between good and bad carbon dioxide

An extended version of the article from Beer Buzz April – June 2019 issue.

In our last article we looked at the some of the containers that beer comes in. This time we are taking a look at something which divides many beer lovers – the role of carbon dioxide (CO2) in beer.

Let’s start by getting one thing out in the open – all beer should have carbon-dioxide dissolved in it. Whether it is a pint of Holt’s cask conditioned mild or Fosters made in Heineken’s factory in Moss Side, there is CO2 in your beer. There are many things that make the two drinks different – that one would be considered ‘flat’ and the other ‘fizzy’ is just one of them.

Carbonation, also referred to in brewing as ‘condition’, is measured in ‘volumes of CO2’. A volume is the space that the carbon-dioxide would take up at a standard atmospheric pressure at a temperature of 0° C. In other words, if a gallon of beer contained 2 volumes of CO2, the CO2 by itself would occupy the same space as two gallons.

A well-kept cask ale at cellar temperature should contain approximately 1.1 volumes of carbon-dioxide. A typical mass-market lager would be expected to contain 2.4 to 2.6 volumes of CO2 where a carbonated soft drink will typically have between 3 and 3.5 volumes. The reaction of the palate to the dissolved carbon-dioxide in your beer is part of the flavour profile – be it the gentle tingle on the tongue of good cask ale or the more pronounced ‘bite’ of a keg beer.

‘Nitro-keg’ beers (including the ubiquitous Guinness) are another category again – these tend to have low volumes of dissolved carbon-dioxide – in the 1.2 – 1.5 volumes region but also have nitrogen injected into them. The nitrogen has smaller bubbles which gives the characteristic ‘creamy’ appearance and mouthfeel. 

There are several ways carbon-dioxide gets dissolved in beer, but the most common is that it is generated naturally during the fermentation process. As yeast sets to work converting sugars in the wort to alcohol, the main biproduct is CO2.  

Many brewers will ferment in sealed tanks so that the naturally generated gas carbonates the beer while others ‘force carbonate’ either by applying CO2 at high pressure and low temperature or by forcing CO2 through the beer using a device known as a carbonation stone (for those of a certain age – think of a SodaStream in action).

A ‘Closed Conical Vessel (CCV)’ at Manchester Union Brewing Company

During cask conditioning, the carbon-dioxide generated during secondary fermentation in the cask is trapped in the sealed cask and absorbed into the beer. Contrary to what some believe, fermentation in a cask does not stop under pressure. There is a relationship between pressure and fermentation rate but at the pressures found in beer production, the effect is negligible and does not slow down secondary fermentation. 

Although commonly referred to as a process which takes place in the pub cellar, beer packaged with live yeast and sufficient fermentable sugars and held at suitable temperature will undergo secondary fermentation whether its in the brewery, in a warehouse or in the pub cellar. 

The levels of carbonation in a sealed cask can be significantly in excess of the expected final 1.1 volumes but the brewer must take care not to allow too much fermentation as the closures on a cask – the shive where a cask will be ‘vented’ and the keystone where the tap will be placed – will only hold back a relatively low pressure.

Cask beer which has been allowed to become too warm will frequently ‘blow’ one of its closures, increased temperature resulting in an increased rate of secondary fermentation and increased generation of carbon-dioxide.

The amount of carbon-dioxide which remains dissolved in a beer is determined by two factors – temperature and pressure. Physics determines the amount of CO2 which will remain soluble in a liquid at a given temperature – the lower the temperature, the more CO2 will remain dissolved.  

In a cask ale the CO2 produced during secondary fermentation stays dissolved in the beer until cask is ‘vented’ in the pub cellar – at which point any excess CO2 will then slowly escape to the atmosphere until it reaches the level which is soluble at cellar temperature. At 13⁰C this is 1.1 volumes and a vented cask beer needs time for the carbonation level to settle. Typically the time taken to vent off excess CO2 also allows other unwanted flavours in the beer to dissipate and desired flavours to develop. 

In a kegged beer higher carbonation levels are maintained by applying pressure to the liquid to keep the CO2 in solution (the skills of applying the right pressures in the cellar are for another day).

In many mass market lagers, carbonation is used to stimulate the tongue and mask the generally low flavour profile. However, for many modern brewers producing ‘craft’ beers for keg dispense, the intended carbonation is very much part of the design of a beer.

‘Craft’ brewers will design their keg beers to have anything from 1.2 to 3.0 volumes of CO2. A carbonation of 2.4 – 2.6 volumes would be typical but lower levels are often used for stouts and porters while highly hopped IPAs may use higher volumes to push out hop aromas from and prevent them tasting cloying.  Too high a carbonation for a given style and ‘carbonic bite’ can become overpowering and masks flavour.

It’s important to remember that all carbon-dioxide is the same gas – there is not ‘good’ and ‘bad’ CO2.  Whether it is generated during fermentation in a tank at the brewery, comes from a cylinder or is generated by secondary fermentation, it is all made up of one molecule of carbon and two of oxygen and once it is in your beer, you have no way of telling how it got there.

Whether you enjoy your beer gently or highly carbonated is a matter of taste.

Cask ale lovers enjoy the creaminess that comes with low carbonation while other drinkers find cask ales ‘flat’ and ‘dull’ and seek the lift from carbonation.  Different beer styles suit different levels of carbonation. There is no right and wrong.

Just enjoy the beer.

 

Explaining Beer Containers – Casks, kegs & KeyKegs

This is an expanded version of the piece which appeared in Beer Buzz January-March 2019

On the way from the brewery to your glass, beer is delivered from a variety of containers, including bottles, cans, kegs, casks and KeyKegs. You all know about bottles and cans, you probably know about casks but what about keg and KeyKeg?

Before we go on, we had better briefly mention the difference between container conditioning and brewery conditioning – we will return to this subject in more detail in future issues.

If beer is container conditioned it means that when put into the container, it still has some yeast and sugars and can continue to ferment and mature in the container. This gives a natural carbon dioxide (CO2) ‘condition’ to the beer – gas is dissolved in the beer naturally and produces the head and ‘bubbles’ when released into your glass. If the beer is pasteurised and/or filtered, then the yeast is killed and/or removed and the beer doesn’t ‘condition’ in the container . It will typically have CO2 (or nitrogen) injected under pressure to give the head and bubbles.

Some beers are conditioned in tanks at the brewery before putting into casks so the beer in the container is ‘bright’ – it contains very little yeast but is not pasteurised. Brewery conditioned beer can be “primed” with the addition of sugar and/or a small amount of yeast at packaging to gain condition in the container without having any significant impact on the flavour.

Generally, most cask beer contains yeast, while mass market keg lagers and “smooth” beers are filtered/pasteurised and artificially carbonated. The modern generation of keg & KeyKeg beers blur the boundaries as the beer they contain can be container or brewery conditioned.

The Cask

The cask is the container from which most ‘real ale’ is served. Most casks are made of stainless steel, although many smaller breweries use lower cost plastic casks. Some breweries still use some traditional wooden casks for special beers – these impart additional flavours to the beer. The Society For The Preservation of Beers from the Wood continues to encourage brewers to keep the traditions of wooden casks alive.

Usually containing some yeast when filled, cask real ale continues to ‘condition’ in the brewery and/or pub cellar. Cask beer is “vented” before service, allowing the carbonation to settle to a natural low level prior to being served. Lower carbonation is one aspect which sets cask ale apart from other formats. Cask ale is most commonly served from hand-pumps but is sometimes directly from the cask (as at beer festivals). In a small number of pubs it is pumped using electric or gas driven pumps to taps either on the bar or on the back wall.

Cask beer can be ‘fined’ (where a material, usually isinglass, is added to help the yeast drop to the bottom), or ‘unfined’ when the yeast drops naturally, sometimes leaving a ‘haze’ to the beer which is quite natural and not a fault.

Traditionally, the cask is placed on its side and beer poured or drawn from a tap inserted at the bottom. A more modern method of service allows casks to be stored upright and served using ‘spears’ that draw beer from the bottom or ‘widges’ that float just below the surface of the beer. The float systems mean the beer is always drawn from the top and therefore avoids the risk of drawing yeast sediment into the feed – assuming of course that the cask has been allowed to settle in the cellar!

As the beer is drawn out, air is drawn in either through a porous spile placed in the shive (the opening at the top of the cask) or, if the cask is vertical, through a vent that forms part of the extraction device.

Air is cask beer’s enemy and will result in the beer oxidising and spoiling if not sold within around 3 days. There is a device called a ‘cask breather’ that draws in CO2 at low pressure to replace the beer drawn out – this can help to prolong the life of a cask beer before it spoils. Some drinkers don’t approve of cask breathers and for many years CAMRA barred beers served on cask-breathers from being listed in the Good Beer Guide. This has now beer withdrawn with CAMRA neither encouraging or discouraging the use of cask breathers.

The Keg

This is the container that most of the major mass-market beers come in – the heavily branded ales and lagers which form the majority of beer drunk in pubs.

These mass-market beers have no yeast in the keg and the beer is pressured from a gas bottle (usually either pure CO2 or a mix of 60% CO2 & 40% nitrogen) in order to get it from the cellar to the tap. Keg beers usually pass through a flash cooler to give the ‘ice cold’ beer that the marketing folks love.

‘Smoothflow’ keg beers (including Guinness) use nitrogen instead of CO2 and are served using a mix of 70% nitrogen and 30% CO2.

Many newer ‘craft’ beers are also served from kegs. Most of these are not ‘conditioned’ in the keg but they will often have lower carbonation than the mass-market lagers and are intended to be served warmer.

The keg connector applies pressure from the top, forcing the beer out from the bottom of the keg via the spear. The pressure applied and the gas used can affect the product in the glass and it is up to the landlord to set the pressure appropriately for the beer. Unfortunately, many pub cellars are set up for serving mass market lagers without the adjustment needed for serving lower carbonation ‘craft kegs’ which can result in ‘craft’ keg beers not being served as the brewer intended.

Most kegs are made from stainless steel, but there are now several variants of plastic keg in widespread use (brands including Dolium & EcoKeg) – these are intended to be disposable, removing the need for brewers to collect empty kegs.

You should not confuse a keg with a KeyKeg, which is a relatively recent invention…

The KeyKeg

KeyKegs are an invention of a Dutch company called Lightweight Containers. They consist of an outer plastic container with an inner non-porous flexible bag that contains the beer. Pressurised gas or air is fed into the gap between the outer and inner containers and the beer is forced out of the feed at the top of the Key-Keg to the tap – the bag collapsing as beer leaves.

The gas never touches the beer so the carbonation level is set by the brewer and cannot be changed by settings in the pub cellar (although it I possible to “vent” a KeyKeg – or any keg for that matter – to reduce the carbonation).

If the beer is conditioned in the KeyKeg, as the gas used for serving it never touches the beer, such beers meet CAMRA’s definition of ‘real ale’. Some brewers are intentionally producing KeyKeg conditioned ales which contain active yeast although the majority of KeyKeg beers are brewery conditioned.

The beer exits via the top of the container with any yeast/sediment collecting at the bottom of the bag – KeyKeg conditioned beers need to be settled in the cellar just like a cask (although KeyKeg conditioned beers are rarely fined so will likely have a ‘haze’).

The majority of the plastic of a KeyKeg is PET, the same material as plastic bottles, however as they need to be dismantled, the UKs recycling industry still makes recycling KeyKegs difficult.

To counter this, the manufacturers have initiated a “OneCircle” project to build a network of collection hubs as part of a logistics operation to route used plastic kegs for recycling, initially in the Netherlands.

Hopefully, this helps you understand how your beer gets from the brewer to your glass. Now what the brewer puts into the container, that is an entirely different discussion!

This article has been adapted from an original piece written by Jack Summers-Glass for InnQuirer, the magazine of CAMRA’s Furness branch.