The science of alcohol
The science of alcohol

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The science of alcohol

2 The brewing process

Have you ever been to a brewery? If not, now’s your chance! In order to illustrate the brewing process, you will now visit (virtually, of course) the Hook Norton Brewery located in the village of Hook Norton, Oxfordshire (Figure 7).

Described image
Figure 7 Hook Norton Victorian tower house brewery

Hook Norton Brewery (referred to colloquially as ‘Hooky’) dates back to 1849 and is referred to as a ‘tower house’ brewery. This means that the stages of the brewing process flow logically from floor to floor, as illustrated in Figure 8.

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Figure 8 Hook Norton tower house brewery schematic

In the following video you will learn from Mark Graham about why Hook Norton uses a tower house brewery.

Download this video clip.Video player: soa_1_w2_s2_vid_graham_brewhouse.mp4
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So this is Hook Norton Brewery. We've got a Victorian tower brewery, designed in 1900 by William Bradford-- designed for a very specific purpose, and that was to brew beer. So it's across five floors. First, the top floor is the-- where the water or liquor, cold water gets pumped up to. Then the next floor down is we've got the grist mill. So that mills the barley. Next floor down, we've got the grist case. So the milled barley goes into the grist case. And then we've also got a hot water tank. So then combine those two together. Floor below is the mash tun. And that's the start in the brewing process, where you mash in, normal about half 6, 7 o'clock in the morning. So once that's done, that gets run off into the coppers, which is, again, another floor down. Then it gets pumped back up into the cooling and then back down again into the fermenting vats, where it sits nicely fermenting for about a week and then gets dropped down through the floor into the storage tanks, into the racking line, into a beer barrel, through the cellar, and out the door and to a pub
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Now watch the actual brewing process utilised by Hook Norton.

Download this video clip.Video player: soa_1_w2_s2_vid_brewingprocess.mp4
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So to make our beer, we'll be easy four ingredients, four raw materials. The first one is water or, as brewers call it in the UK, certain liquor. That's very important, and that's one of the reasons why the brewery is established where it is here. We have quite high mineral content in our water here, which is particularly good for ales. And we're still using water from our own borehole-- so the original aquifer. It's actually through millstone rock from the Mid-Jurassic period. The other ingredients are barley malt. We're using a cereal to give our fermentable sugar, and essentially that's barley malt, although sometimes we might use a little bit of wheat or rye or even oats. We're then going to flavour the liquid we produce with hops and then ferment it with brewer's yeast. So at the beginning of the process, we need to mix the malt and the hot water, the hot liquor together. So the malt will be gently milled the day before we're actually going to use it to crack the grains open very gently. And then when we mix that, the first stage in the brewing day, usually early in the morning, sort of 6:00, 6:30, we'll mix together a large quantity of crushed malt with hot liquor, and it looks something like a porridge type consistency, sort of smells like that. So it's lovely to see that first thing in the morning. We're then going to leave that. That needs to stand for a period of time during which the enzymes that are naturally present in the cereal grains will start to turn the starch into sugar. So once we've mixed it all together, we're typically going to allow it to stand for between an hour and an hour and a quarter. After that time, we'll find that we have our sugars produced, and we can then start to extract those sugars. And basically what happens is we run the liquid content off into a copper, a brew kettle, and at the same time, we'll wash hot liquor on top of the grain, so effectively wash the sugars out and into the copper. And obviously, we balance up the quantities of raw materials we're using to reflect how much finished beer we want at the end of it. So we've had our stand for an hour, hour and a quarter. We're then going to start running the wort off. Wort is the term for unfermented beer. And the process called sparging where we spray hot water, hot liquor on the grains and basically wash the sugars into the copper-- and that takes typically between two to three hours. Then we're looking at hops as one of our key ingredients, and hops give beer both bitterness and aroma. There are a range of different hop varieties, and hops are available from different countries around the globe. And depending on the climate they're grown in and the variety that you're using, that can reflect whether a hop, perhaps, gives more bitterness or more aroma. So the brewer will select their hop variety on a seasonal basis for what they think they're going to brew sort of for the coming year. So we will add our hops to the copper. If you want bitterness from hops, you typically need to boil them for at least half an hour. So we're going to be boiling for an hour in total. And with the particular beer we're doing today, some hops will go in at the beginning of the boil and some hops will go in at the end of the boil. And the reason the hops are going in at the end of the boil is because we want those to give the beer aroma but not bitterness. So I often think-- think Mrs. Beeton's recipe books and align that to brewing because it's very similar in those terms. So we'll boil for an hour and get our bitterness from the hops that we want and our aroma from the later hops that we add. We'll then philtre those hops out by going through a large strainer vessel. And then we're ready approaching the time to add the yeast, to ferment the sugars and actually turn the wort into beer. But obviously, because we're boiling, we do need to cool the wort down to a suitable temperature, otherwise it would kill the yeast if we added it when it was too hot. So we'll go through a heat exchanger, and we're looking to cool our wort down from a boiling point temperature down to about 16 to 17 degrees centigrade, 62, 63 degrees Fahrenheit into a fermenting vessel. So that's a large open tank. And then we will add a measured amount of our uncultured yeast and fermentation will begin, and that will typically take about a week. During that period of time, the yeast will reproduce. The yeast will multiply. The yeast will turn the sugar into alcohol and also develop a lot of other flavours. And we'll actually harvest some of the yeast off the brew, as well, because it reproduces. And we'll keep that yeast to then use for future brews the following week.
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Activity 1 The order of the brewing process

Timing: Allow approximately 5 minutes for this activity

After watching the video can you list the different constituents of the brewing process in order?

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The constituents are:

  • malting
  • mashing
  • boiling
  • fermentation.

These steps are summarised in the following sections.


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