The science of alcohol
The science of alcohol

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The science of alcohol

3 Types of beer

Beer can be classified using various factors – colour, flavour, strength, ingredients, production method, recipe, history, or origin.

  • How many different styles of beer can you list?

  • You may have listed some (or all) of the following as styles of beer that can be readily purchased – pale ale, brown ale, pilsner, lager, bitter, stout, wheat beer (Weissbier), Trappist beer… But in fact, scientifically, most beers can be classified into just two types, ale and lager, and all of the other styles of beer can be grouped into one of these two types.

Although the systematic study of beer styles is a modern phenomenon, the practice of distinguishing between different varieties of beer is ancient, dating to at least 2000 BC.

Most beer styles fall into types roughly according to the time and temperature of the primary fermentation and the variety of yeast used during fermentation. As the terminology of brewing arose before the science of microbiology, ‘yeast’ in this context may refer not only to fungi but to some bacteria, for example Lactobacillus in Berliner Weisse.

Now watch the following video of Danny Allwood describing three of these different styles of beer.

Download this video clip.Video player: soa_1_w2_s3_vid_typesofbeer.mp4
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Transcript

DANNY ALLWOOD
There are hundreds of different styles of beer. These are broadly categorised into ales and lagers. The only real difference between ales and lagers is that ales are fermented with one type of yeast, saccharomyces cerevisiae, which ferments at warmer temperatures. And lagers are fermented with saccharomyces pastorionus, which ferments at lower temperatures. So lagers tend to be stored colder for longer. But they're all produced in broadly the same way. Now, beer styles developed because certain areas of the world produced a particular style of beer. And when we were back in the days of yeast spontaneously dropping into worts and fermenting it, so we're using the wild yeast, which grows naturally around that region, you would produce certain styles of beer. It's also to do with the water quality. So areas with high-carbonate water would tend to produce darker beers, because darker malts are more acidic, so they lead to a more balanced flavour. But the style of beer that you're brewing, nowadays, we largely used it to categorise beers for purposes of judging competitions and that sort of thing, but also so consumers know roughly what they're getting when they order a certain style of beer. But what your beer ends up tasting like and looking like is determined by the ingredients and the processes that go into making it. So you can't necessarily look at a beer and decide whether or not it's high or low-alcohol, whether or not it's dry or sweet, whether or not it's hoppy or malty. Those all come from the process. And we use beer styles as a way of giving the consumer an idea about what they're going to expect when they drink this pint. So here we are three examples of different beers. You can see visually, they're all quite different. And the first thing that we look at when we look at a beer style is the colour. So this one over here is a very pale straw colour. That means that when the malt that went into it were mostly very pale malts. So they might have used a little bit of crystal malt or caramel malt. But mostly, this is made with base malt. This one over here is a little bit darker, so there's likely some more speciality malts in this, more crystal malt, more caramel malt. So this is likely to be a little bit sweeter, likely to have more caramel, bready, nutty-type flavours in it. And this one in here, as you see, is very, very dark. This has got some dark malt, some coloured malt in it, something like black patent malt or roasted barley. So this is likely to be roasted coffee-type flavours. There's a common misconception that darker beers are stronger. That's not necessarily true. So the alcohol content of your beer is determined mostly by the grain content. So how much grain went into making that beer? So you can have a pale beer like this, which is 8%. If you've ever had a double IPA, they'll be very alcoholic indeed, but they'll be as pale as this one. And you can have session stouts which are 3%. So ABV and colour are not necessarily linked. It's all to do with the amount of malt you use and the type of malts that you use. One thing that Brewers are mainly looking for is balance in their beer. They want their beer to be a balance between malty flavours and hoppy flavours, principally. Yeasty flavours sometimes get in there as well, but that's much more of a style specific thing. So over here, we have a lager. This is, as I say, brewed with saccharomyces pastorianus, so it's a period of cold conditioning. And what that aims to do is cut down on the number of fruity, what we call ester compounds, which are produced by ale yeasts at higher temperatures. So the aim with a lager is that it is very crisp. It's very dry. Lagers tend to be also mashed at a low temperature. That gives you fewer unfermentable sugars in the finished beer, so it will have a less sweet, a drier overall mouthful. You might be able to see in the glass as well there's bubbles rising in it. Lagers tend to be highly carbonated because they're intended to be crisp, dry, and refreshing. If we move across to this here in the middle, this is an ale. It's slightly less carbonated than lager, ales tend to be. If you get beer in a pub, which is on a hand pump, that's not artificially carbonated. That's pumped directly up from the cellar, so they tend to be a little bit less fizzy. They tend to fill you up a little bit less. So they're usually a little bit less refreshing. They're also served less cold as well. The stout, on the other hand, is a very malt-forward beer. We're showcasing the dark malts, the roasted barley, the roasted coffee-type flavours. It's not very highly carbonated. It's not intended to be very fizzy. It's a relatively flat beer. But you can see on this one that the head is bigger than on the other two. So this has compounds in it which are contributing to head stability. And in things like stout where your flavour profile that you're going for is coffee, kind of creamy sort of mouth feel, the head is really important. And the head is really important in a lot of beer styles. The head traps volatiles. It makes the beer smell better. It makes it taste better in your mouth. So as I mentioned before, it's very difficult to judge at first glance what your beer's going to be like, what it's going to taste like. For instance, you might-- there's another common misconception about dark beers and stouts is that they're very sweet, and they're very heavy, and it's a meal in a glass. This particular stout is very dry. It's got a very dry finish. It's not very sweet at all. So although beer styles are useful in anticipating what kind of beer you're going to get, mainly what contributes to the flavour, and mouth feel, and aroma of your beer is the ingredients and the process which went into making it.
End transcript
 
Interactive feature not available in single page view (see it in standard view).
  • What are the two main differences between the fermentation of a lager and an ale?

  • Lagers are fermented using the yeast Saccharomyces pastorianus whereas ales are fermented using the yeast Saccharomyces cerevisiae.

    Lagers are fermented at lower temperatures than ales.

SOA_1

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