The science of alcohol
The science of alcohol

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The science of alcohol

1 The components of beer

You may be surprised to hear that there are only four key components of beer, regardless of what type of beer is being brewed.

Before considering the process of brewing you can explore the different components of beer by watching the videos below. In the sections which follow, you will explore in detail the brewing process at Hook Norton but, before this, it is useful to know a bit more about each component individually.

The following videos will show you more about the role of the main components of beer: barley, water, yeast and hops.

Download this video clip.Video player: Barley
Skip transcript: Barley

Transcript: Barley

DANNY ALLWOOD
So barley is a cereal grain. It's the fourth most widely cultivated crop in the world, after corn, rice, and wheat. It's a member of the grass family, so it grows as these upright stalks. And the ears at the top here are where the barley grains actually grow, from where they're harvested from. So these are what we need in the brewing process. But we can't use raw barley grains in the brewing process. We need to do something to them first, and that process is malting. So what malting does is it takes the barley grains, and we soak them in water. And that raises the moisture content to allow germination to occur. And we allow the barley to undergo a controlled germination process, which is what barley normally does in order to grow new barley plants. So by allowing the barley to germinate, we raise levels of key components which we're going to need for the brewing process, things like enzymes. So enzymes like amylase play a really important role in the mash, and it's what allows us to break down the carbohydrate, which is in barley, into sugars. And if we break down carbohydrate starch into fermentable sugars, that will allow our yeast to ferment our wart and eventually become beer. Now, the final stage of the malting process after we've sold the grains and allowed them to germinate is kilning. And that basically dries the grains out, which means that we can store them for long periods of time and use them whenever we want. But by kilning using different temperatures and for different amounts of time, we can end up with different types of malt. So what we have here is malted barley. And this is uncrushed malted barley as it comes straight from the maltster, and this is what is generally delivered to brewers. So in order to use that carbohydrate, which is trapped in those kernels, we need to crush it. And sometimes this is done in the brewery. Sometimes this is done at the maltster, and they deliver it to you crushed. But here is crushed malt. And you can see that it's been broken apart and all of the grain husks are mixed in with these little white parts here, which is where all of the carbohydrate, all of the starch is. And that's going to provide the sugar which we need for brewing. So what we have there is what we call base malt or pale malt. And the primary role of pale malt is to provide the carbohydrate, which is going to become alcohol. That provides us with the alcohol in our beer. It provides us with a little bit of flavour as well, but it's mainly to do with giving us alcohol. By kilning hotter or for longer, we can caramelise some of these sugars that are found in the malt, and we end up with darker malts. Now, kilning hotter destroys the enzymes. So we can't use these malts to mash, to convert carbohydrate into sugar, but we can use them to impart flavour. Now, what we have here is crystal malt or caramel malt. And you can see that it's darker. If I hold it up side by side with the pale malt, you can see that it's darker than the pale malt. That's because chemical reactions have occurred called Maillard reactions. And these provide compounds which provide flavour, caramel flavours, biscuity flavours, cereal flavours, that sort of thing. So generally what you will do when you design a grain bill for your beer is between 60% and 80% of it will be base malt. You will then add specialty malts to provide extra colour and flavour. These malts also provide unfermentable sugars which stay in the beer after fermentation's occurred, which makes for a sweeter beer. If you take the kilning to the extreme, you kiln very hot for very long periods of time, you end up with coloured malts. And an example, this is the most extreme example of this, I suppose, is black patent malt, which is what we've got here. And by darkening the malt to this extreme, we've destroyed all of the enzymes in there, so there's no enzymatic activity coming from this malt. But there is a lot of flavour active and colour active compounds in here. So this malt will darken the beer. So you only need a very small amount, generally between 1% and 5% in your grain bill. But it will also impart nutty flavours, coffee flavours, very roasty flavours. If you add too much, it can become acrid and burnt. But this is a key component in stouts and another dark beer styles. So the different types of malts and what you put into the grain bill contribute to your malty flavour of your beer. If what you're aiming for is a more malt-forward beer, then generally you'll have more specialty malts, more dark malts, that sort of thing in there. If what you're aiming for is a hop-forward beer to showcase hops, then you'll go for a much simpler green bill generally, where you just have usually the pale malt, the base malts, and you'll let the hops shine. Quite often, you can end up with a balanced beer where there's a little bit of everything, which is important as well. But malt here is a key component in beer flavour.
End transcript: Barley
Barley
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Download this video clip.Video player: Water
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Transcript: Water

DANNY ALLWOOD
So the ingredient that makes up the vast majority of beer is water. Now water is water, H2O. But what's dissolved in water can have a massive impact on the brewing process. Now, there are some key ions which are involved in brewing, things like calcium, magnesium, sodium, and also anions like sulphate, carbonate, and chloride. Now, these appear naturally in tap water. And where you brew in the world will determine what your iron concentration in your water is. So if you live in a very hard water area, your iron concentration will generally be quite high. And when we talk about hard water, generally what we're talking about is carbonate, and that's the lime scale that you see on the inside of the kettle. That's calcium carbonate deposits. Now, calcium is vital to the brewing process. It's vital to the enzymatic reactions that occur in the mash. But carbonates can raise the alkalinity of your mash water, and that can cause some issues if it gets above a certain threshold. So traditionally, high carbonate water has not been considered the best for brewing. Now, dark malts such as black patent malt are acidic, and they will lower the pH of your mash. They'll lower the alkalinity. So traditionally, areas that had poor brewing water that was high in carbonate would brew dark beers. Now, the place that was famed for pale ale and revolutionising pale ale was Burton on Trent. And that's because Burton has a very unique iron concentration in its water. There's a lot of calcium sulphate in Burton water. So calcium, as we said, vital for the brewing process. But sulphate is an iron, which increases your perception of bitterness and of hoppiness. So hoppy, bitter ales which are brewed in high sulphate water generally taste better than the ones which are brewed in low sulphate water. There are other ions as well, such as chloride. Chloride improve your perception of sweetness or maltiness. So generally areas that are high in chloride will tend to produce malty beers. And this is just a historical process. You know, people brewed the beers which tasted the best of them, and without really understanding the water chemistry which is going on. So what happens nowadays is that breweries can adjust their water chemistry depending on what sort of beer they want to brew. And there's a process called Burtonization, which is where you add gypsum or calcium sulphate to your brewing water, which produces a water profile very similar to what they have in Burton on Trent. So it's ideal in places like Sheffield around where I am. We are very, very soft water, not very many ions in it at all. You've got a blank canvas to start with and you can add ions in the form of metal salts as you wish to your brewing water to produce whatever you want to produce. If you live in a very hard water area which is high in carbonate and other things, you may have to cut your brewing water with distilled water to try and bring the ion concentrations down to something which is more sensible. But wherever you live, it's possible to brew great beer. You just have to be mindful of what sort of ions are living in your water.
End transcript: Water
Water
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Download this video clip.Video player: Yeast
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Transcript: Yeast

DANNY ALLWOOD
Yeast is a microscopic fungus. And the name saccharomyces, which is the species of yeast that we use in brewing, literally in Latin means "sugar fungus." So it's a fungus that eats sugar. And it produces carbon dioxides and ethanol as a byproduct. So in antiquity, what used to happen in the brewing process was that you would produce wart by the mashing process. And after you'd got your wart, you would leave it out. And something miraculous would happen. It would start producing gas. Foam would appear on the top, and it would turn into beer. It would turn alcoholic. Now, they didn't realise that what was happening was wild yeast, which is everywhere around us in nature, were getting into the beer or into the water and turning it into beer. So nowadays, because we know that it's yeast which actually does this, we can isolate yeast. We can grow up yeast. We can produce yeast. We can sell yeast. So when brewers produce beer, they don't have to rely on wild yeast coming in and infecting their water and producing beer. They can buy yeast from manufacturers or they can propagate their own. So generally how it comes is either as dry yeast, which looks a little bit like this. It just looks like a powder. You might have used this in baking bread at home. Baker's yeast is slightly different to brewing yeast, but there's broadly similar things. Or you can buy wet yeast, which comes as a sort of solution in a pack. But they all work in broadly similar ways. So after you produce your wart, you simply pitch the yeast into it, and it goes to work. Now, the first thing that the yeast will do is it will go around looking for fermentable sugars. These are sugars which are small enough for the yeast to eat, to process, and turn into ethanol and carbon dioxide. And that's what we call primary fermentation. And that's accompanied by vigorous gas evolution. So you'll see a lot of bubbles coming off the top of your fermenting beer. After primary fermentation is complete, the yeast's job isn't finished. They then go around looking for waste compounds, things that they've produced in the process of producing ethanol, and basically clearing up after themselves. And this is what we call secondary fermentation, or the conditioning process. So if you taste your beer as soon as the gas evolution is finished, it might taste a little bit strange. If you give it another couple of weeks, the yeast will go to work and control some of these off flavours, process some compounds, and turn it into something that takes a bit more even, more levelled out. So yeast themselves, some beers are what we would call yeast-forward. The yeast is the major contributor. A lot of Belgian styles which are very spicy, peppery, fruity kind of beers, the yeast is responsible for those kind of flavour compounds. German wheat beers, Hefeweizens and things like that, you'll notice that they're cloudy. That's the yeast in suspension. And these are typically flavoured with clove or banana. And those flavours don't come from clove or banana. They're compounds which are produced by the yeast during natural fermentation. So yeast themselves, you might think don't contribute an awful lot to the flavour of the beer, but they're a massive, massive contributor to the overall flavour profile of any beer.
End transcript: Yeast
Yeast
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Download this video clip.Video player: Hops
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Transcript: Hops

DANNY ALLWOOD
So hops are a climbing perennial plant. They've found throughout the world, but they're native to Europe, to North America, and to Asia. They've been introduced to Australia. They'll grow basically anywhere that there's a temperate climate. And because they're climbers, they will generally need a support to climb up. Now, on hop farms, this is a wire or a trellis. But in the wild, they'll grow up trees or rock faces or anything they can get their hands on, really. Now, hops produce flowers. They don't look like flowers that you would normally see on plants. They're just green. And they have these petals on them. But at the base of these flowers are something called a lupulin glands, and these give us a substance of lupulin, which is a waxy, oily, yellow solid. We'll come back to lupulin in a moment. So when brewers receive hops from the hop grower, they generally come in one of two forms. They come as whole flowers, and these look like this. Now, you'll see that they look a bit flatter than the ones that I just showed you. That's just because they've been pressed and then vacuum packed for storage. It's really important that you keep these under vacuum packing if you're going to be storing them for a long period of time. The other way that they might be provided is as pellets, and these are basically hops that have been shredded and then pressed into pellet form, and the pellets are sort of held together by the lupulin, which, as I said, is this oily, resinous, yellow compound. And the pellets just take up less volume. They're easier to transport. You can get more hops in a smaller amount of space. So as I said, lupulin is the key kind of thing for hops, and it's what we're after in the brewing process. So lupulin is composed of a vast array of different molecules. But the vast majority of lupulin falls into two main categories. There's the alpha acids, and there are the hop oils, and both of these play a key role in the brewing process. So alpha acids are compounds which isomerize at high temperature, and that means that they rearrange. So they form a different molecule, which has the same atoms in it. Now, in the boil process of the brew, we add hops to the boil, and the alpha acids, as soon as they get above about 80 degrees, isomerize. And these iso-alpha acids, these isomerized alpha acids are what gives beer its bitter flavour, and that's where the bitterness in beer comes from. So the more hops you add early in the boil and the longer you boil them for, the more bitter your beer will become. The other aspect of lupulin is the hop oils. Now, hop oils are what give beer a hoppy flavour and aroma. So if you hear a beer described as being hoppy, that's generally what they're talking about is that hoppy aroma and flavour that you get when you drink the beer, not just the bitterness. Now, the issue with hop oils is that they're volatile, meaning that they boil off quite readily. They turn from liquid into the gas phase quite easily. So if you boil hops for a prolonged period of time, generally the hop oils will boil off and you won't get a hoppy aroma and flavour. So what we need to do in the brewing process is add multiple additions of hops at different times throughout the boil. If we had our hops right at the beginning of the boil, all of the hop oils will boil off, so we won't get any aroma or flavour, but the alpha acids will isomerize, and we'll get a lot of bitterness. If we add hops at the end of the boil with only a few minutes left, we won't get very much bitterness, because the alpha acids don't have time to isomerize, and we'll retain a lot of those hops oils because they won't have time to boil off. So the amount of hops that you use and when you add them in the boil is largely dependent on the beer style. If you're making a very hop-forward beer, which is what's currently a driver in modern brewing is very hop-forward beers driven by things like the American IPA, then you'll use a lot of what we call late-boil hops, so a lot of hops late on in the boil to try and retain as much of that hoppy aroma and flavour as you can. If you're brewing a beer where the focus isn't on hops, like a multi beer, then generally you'll just have a bittering addition, which is at the start of the boil. You're using the alpha acids, but not the oils. And you'll just get that bitter flavour, but you won't get the hoppy aroma and flavour. And that's generally for beer styles such as stout. So hops aren't the only thing which contribute to the flavour of the beer. Obviously I mentioned multi beers there. But they are a substantial contribution towards the flavour of a beer. And especially in modern brewing, in modern craft bringing, the focus tends to be very much on hops.
End transcript: Hops
Hops
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