Think of pasteurisation and the chances are you’ll instantly think of one thing: milk. These days, most milk is indeed pasteurised, keeping it fresh for as long as possible. But actually the truth behind pasteurisation is far more intoxicating. Back in the 1860s, eminent French chemist and microbiologist Louis Pasteur pioneered the technique as a new way to stop beer and wine from souring.
This discovery wasn’t lost on the great grandfather of our master brewer, Jef. While serving in the First World War, Paul Van Steenberge, was captured in August 1914 and interned across the Dutch border. He was placed in the microbiology laboratory of the Technical College in Delft with Professor Beyerinck, a former student of Louis Pasteur. So he learnt the science behind beer as well as the expert skills of a master brewer.
So what is pasteurisation all about? It’s designed to prevent or delay the growth of microbes in liquids. It works by heating the liquid to a specified temperature for a set amount of time, and then cooling it down right away. Most brewers pasteurise beer after it has been bottled or canned, by running the container under a hot water spray for two to three minutes. At around 60 Celsius, the water is hot enough to kill most microbes.
So what’s best? Pasteurised or non-pasteurised? These days, most beer is pasteurised, but it’s still a hotly debated subject in the brewing – and beer-drinking – communities. For many brewers, the benefits are clear cut. First, shelf life can be extended by up to 120 days, depending on the type of beer and the method of pasteurisation. Second, the process can halt or prevent secondary fermentation, particularly for beer in kegs. On the other hand, some believe that pasteurisation affects the taste of beer for the worse.
And in the end, that’s what it’s all about - the taste. No two bottles of St Stefanus will ever taste quite the same. That’s because we’re firm believers in the power of the living yeast at the heart of our beer. So the longer the yeast has to mature and develop, the more intense and fruity the flavour.
What’s more, our beer comes with a long shelf life, despite being unpasteurised. There are two reasons for this. First, it has a high alcohol content, with an ABV of 7% - much higher than ordinary lagers. Second, it has a high hopping level, with the acids within the hops having great antiseptic qualities, aiding in shelf life and yeast’s ability to grow. So if you store your St. Stefanus in a cool, dark place then your beer will stay fresh for up to two years: it’s as simple as that.
What’s your take on the pasteurisation debate? How does the taste of pasteurised and non-pasteurised beer compare? Drop us a line and let us know what you think.