How Does Non Pasteurised Beer Differ?

Certain beers use their non pasteurised status as a selling point, but how does non pasteurised beer differ and why is it more appealing to the beer connoisseur?

Louis Pasteur’s Legacy

The triumphant endeavours of French chemist and microbiologist Louis Pasteur in demonstrating that micro-organisms were responsible for souring wine and beer and could be slowed by short exposure to high temperatures was to have a hugely significant impact on the brewing world.

Brewers who had previously struggled to keep their beer fresh tasting, particularly in warmer climates and in the growing production of beer that was paler and lower in alcohol and therefore harder to preserve, were able to keep their beer for much longer.

Whereas unpasteurised draft beer has a life 45 to 60 days from when it leaves the brewery, pasteurised draft can live as long as nine months. Once a cask is tapped and the beer starts to react with oxygen then it starts to deteriorate even faster. Although the stronger and the higher hopping level of the beer, the longer it will last, as a guide a 4% beer will typically last around three days.

In allowing brewers to stabilise and preserve their beer, pasteurisation helped expand the brewing industry. In allowing brewers to operate on a much larger scale it has facilitated the creation of beer that has a much higher tolerance for changes in temperatures and any knocks experienced during shipping and storage and so can better endure both international and domestic export.

Bad News for Beer

Although pasteurisation has been great news for the development and efficiency of the brewing industry it has come at the expense of the beer itself. Many brewers believe that by pasteurising the beer and killing off the active yeast organisms you remove a lot of its character.

When the beer is typically heated to a temperature of over 60°C for between 25 to 30 minutes so that the microorganisms present can be largely eliminated, it guarantees a longer lifetime for the beer but such a drastic practice damages the beer’s natural taste, colour and aroma. Unpasteurised beer is said to have rounder and more complex flavour.

Most foods are not commercially sterilised because of the negative effects the process has on the taste and quality of the product, so why should we expect it not to affect our beer similarly? It may be argued that brewers employ a less invasive form of sterilisation known as ‘flash pasteurisation’ but still this does not prevent some of the natural characteristics of the beer from being spoilt.

Furthermore, pasteurisation can greatly increase the beer being subject to oxidation, which in turn can lead to staleness or the surfacing of unappetising off-flavours.

Try Unpasteurised Beer

It is not surprising then that pasteurisation is not a celebrated word amongst beer lovers. Even though it is common for both large and small-scale breweries to pasteurise their beer, the term has become synonymous with artificially processed mass produced beer.

This in part explains why a beer billed as being ‘unpasteurised’ – or unfiltered – is now a recognised selling point amongst more discerning drinkers. It is as a sign of more natural, and therefore superior quality, quality. Whether it is actually any better or not remains to be seen, but it does at least show a more honest approach from the brewer towards the consumer.

Besides all cask-conditioned ales, which are by definition unpasteurised, as well as unfiltered and unpressurised, it is becoming increasing easy to sample unpasteurised beers through brewpubs. As beers are brewed and drunk on site there isn’t the same demand for shelf life and what’s more these places invariably take pride in serving a truly natural product.

Tank Pubs

For untreated pilsner then the Czech Republic is a rich source of unpasteurised fulfilment. Whereas the rest of the world get the original golden lager Pilsner Urquell in a treated pasteurised form, the Czechs keep a more appetising natural unpasteurised version all to themselves. This is available in the hundreds of special pubs across the Czech nation known as ‘tankovna’. Instead of the beer being dispensed from barrels, it is pumped directly into temperature controlled plastic sacks inside massive on-site tanks.

Tankovnas are now very popular in Prague and as the big breweries have got in on the act, it is now possible to taste unpasteurised versions of other big Czech beers like Budvar, Krušovice and Staropramen.


Another large Czech brewery, the independent Bernard, takes a harder stance on pasteurisation and the harm it does to their beer and has developed its own alternative technique, a more sensitive processing known as microfiltration. According to the brewer, it is more demanding route but one that guarantees the unique features of the beer will still remain when the beer is tasted by the customer.

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