Understanding the formats beer comes in
The story of a beer may well start as an idea in the brewer’s mind, or with the ingredients that enable their recipes to shine. The container plays just as important a role in the development, transportation, and enjoyment of beer by the drinker. Different containers allow specific types of beer to be enjoyed at their best. Understanding containers, like getting to know hops and malts, allows us to make more informed choices when selecting that next glass at the bar.
A CAMRA member since 1997, John is volunteer with a keen interest in the technicalities of beer dispense, a GBBF bar manager, editor of Manchester’s Beer Buzz magazine and sits on CAMRA’s Technical Advisory Group.
On the way from the brewery to your glass, beer is delivered from a variety of containers, including bottles, cans, kegs, casks and various ‘membrane kegs’ (of which KeyKeg is the most common). You all know about bottles and cans, you probably know about casks but what about the different types of keg?
Before we go on, we had better briefly mention the difference between container conditioning and brewery conditioning – this subject will be covered in future Learn and Discover pages.
Conditioning refers jointly to the processes of maturing beer to develop its final rounded flavours and to the method by which beer is carbonated – two processes which go hand in hand to produce a finished beer. Most beer is force carbonated – literally forcing carbon dioxide (CO2) pressure into a sealed tank until it dissolves in the beer – this can only be done in the brewery.
The alternative is to condition beer by the action of yeast on residual sugars to generate CO2, a method also known as secondary fermentation. This latter method of conditioning can also take place in tanks in the brewery before beer is packaged or can take place in its final container. Whether that container is a cask, a keg, a can or a bottle, the process is similar – the beer put into the container isn’t finished. It contains live yeast and sugars and continues to ferment and mature in the container.
In the 70s and 80s most draft beer clearly divided into either cask-conditioned ales or filtered, pasteurised and force carbonated keg beers. However, as with many brewing processes, modern technology has brought more complexity to the conditioning process than we can cover here. The modern generation of tech blur the boundaries as the beer can be conditioned in their container and may even be brewery–conditioned as well, as well as being force carbonated in the “normal” fashion.
In the UK, the cask is the container from which most ‘real ale’ is served. Historically casks were made from wood but in the latter half of the 20th century, metal casks took over being longer lasting and easier to clean. Most modern 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 can impart additional flavours to the beer, particularly when they are unlined. The Society for The Preservation of Beers from the Wood (SPBW) continues to encourage brewers to keep the traditions of wooden casks alive.
Usually containing some yeast when filled, a cask of beer continues to ‘condition’ in the brewery and/or pub cellar. The cask is “vented” before service, allowing the carbonation to settle to a natural low level prior to being served. Lower carbonation is one aspect that sets cask ale apart from other formats. Cask ale is commonly served from hand-pumps but is sometimes served 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 additions, usually including isinglass, are added direct to the cask to speed clarification of the beer or ‘unfined’. Fining is a subject for a future Learn & Discover piece but it is worth noting that when cask beer is referred to as ‘unfined’, this commonly means ‘not fined using isinglass’ rather than meaning ‘intentionally hazy’.
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 reduces the risk of drawing yeast sediment into the feed – provided the cask has been allowed to settle in the cellar!
As the beer is drawn out, air is drawn in either through a porous peg, or 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 time before a cask beer 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 been withdrawn with CAMRA neither encouraging nor discouraging the use of cask breathers.
This is the container that most mainstream beers come in – the better-known lagers and ales that make up the majority of beer drunk in British pubs. Invented in 1936 kegs were initially used for export but by the 1950s began to become commonplace in British pub cellars and grew in prominence over the following thirty years.
Most mainstream keg beers are carbonated in the brewery and have no yeast in the keg. However, many small independent breweries frequently use both kegs and membrane kegs (see below) to sell beers that contain live yeast in a sealed container designed for draught dispense.
The keg connector applies gas from the top of the beer (leading to this method of dispense sometimes being referred to as ‘top-pressure’). This pressure forces the beer out from the bottom of the keg via the spear – a long tube which runs from the keg connector to the base of the keg.
The applied gas is usually either pure CO2 or a mix of 60% CO2 & 40% nitrogen. ‘Smoothflow’ keg beers (including Guinness) use nitrogen instead of CO2 as it has smaller bubbles. Smoothflow beers are served using a mix of 70% nitrogen and 30% CO2.
The pressure applied and the gas used can affect the product in the glass and it is up to the cellar engineer to set the pressure appropriate to the beer and cellar temperature. A well-adjusted cellar should apply pressure to maintain the carbonation of the beer as set by the brewer. Unfortunately, many pub cellars are set up for serving mainstream lagers and ales and the adjustments needed to serve lower carbonation beers (as the brewer intended) is not always possible or achieved.
Keg beers usually pass through a flash cooler to chill the beers to a much lower temperature, even “ice-cold” in some instances. There are many reasons why both suppliers and customers want very cold beer, but that is a topic for a different discussion.
Most kegs are made from stainless steel, but there are now several variants of plastic keg in widespread use (brands including Dolium & EcoKeg).
Originally designed for the export market these are also commonly used where brewers ship beers domestically on pallets, plastic kegs are intended to be “one-way” or “non-return” — i.e. they are disposed of or recycled by the recipient rather than returned to the original brewer. Some brands (such as EcoKeg) feature a reusable outer jacket and recyclable inner container. One-way kegs also have the advantage of being a lot lighter than metal kegs impacting on carbon emissions emitted through distribution of beer via road freight.
Readers should not confuse a one-way keg with a membrane keg which is a relatively recent invention…
Keg beers usually pass through a flash cooler to chill the beers to a much lower temperature, even “ice-cold” in some instances. There are many reasons why both suppliers and customers want very cold beer, but that is a topic for a different discussion.
A membrane keg is a special type of one-way keg which consists 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 keg to the tap – the bag collapsing as beer leaves.
The best-known brand of membrane keg in the UK is the KeyKeg, invented by a Dutch company called Lightweight Containers in 2006. Although the KeyKeg is, at the time of writing, the most widely used by UK brewers, recent years have seen other manufacturers introduce similar containers to the UK market.
In a membrane keg, the dispense 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 membrane keg – or any keg for that matter – to reduce the carbonation if so desired. One of the other benefits of this system is that any gas can be used to dispense the beer, including (non-sterile) air from portable dispensers which incorporate an air compressor, chiller and tap in one unit.
The beer exits via the top of the container with any yeast/sediment collecting at the bottom of the bag – keg conditioned beers need to be settled in the cellar just like a cask (although keg conditioned beers are often unfined so will likely have a ‘haze’).
The majority of the plastic used in one-way kegs is PET, the same material as plastic drinks bottles. The need to separate the bag from the plastic outer has meant the UK’s recycling industry has been slow to facilitate the recycling of membrane kegs. However, initiatives are well-advanced to make all one-way kegs largely recyclable. The relative environmental impacts of plastic waste and the use of cleaning chemicals when reusing containers has yet to be balanced.
Hopefully, this article 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.
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