Science of Scotch: How whisky is made
PodcastsThe Naked ScientistsScience of Scotch: How whisky is madeA Burns Night special. . . 21 January 2025In this special episode of The Naked Scientists, join Chris Smith on a journey from farm to whisky. . .
PodcastsThe Naked ScientistsScience of Scotch: How whisky is madeA Burns Night special. . . 21 January 2025In this special episode of The Naked Scientists, join Chris Smith on a journey from farm to whisky tumbler, as he witnesses the intricate processes behind producing high quality Scotch. Richard Broadbent leads a tour of Bairds Malt's site in Witham, explaining how British barley is prepared for its transformation into the delicious spirit, before Alistair McDonald of the Clydeside Distillery in Glasgow walks us through the five hundred year old craft of distilling malt whisky. . . Malting barley to make the best whiskyRichard Broadbent, Station MaltingsMaking great whisky starts with the malting process, where the best quality barley is steeped in water to start it germinating, so it ramps up enzyme activity and beings to unlock the chemical energy stored in the barley seeds. Chris Smith met up with Richard Broadbent of Station Maltings in the nearby town of Witham, in Essex…Richard - So we're heading down to our barley intake weighbridge area. Each lorry load of barley that comes to us will weigh around about 29 tonnes, and we have to carry out a number of quality analysis on each load that arrives on site before we tip it and accept it from the farmer. We keep around about 35,000 tonnes of stock at any given point. During harvest, we take in the majority and then we fill up our silos as as full as we can get them. And then as we use barley through the rest of the year, we refill them. Chris - Now why barley? Why is that so special?Richard - Barley is the perfect cereal for making whisky. Barley has a very strong husk, which protects the grain during our processing. It has a high amount of starch, protein and enzyme potential, all of which are important to the brewers and distillers later. And our climate is perfect in the UK for growing multi barley as well. Chris - Where are we going now?Richard - We'll head up to the barley weighbridge up here, and have a look at some of the barley that we brought in today. Chris - Lead the wayRichard - So we're in our barley intake lab. So this is where we carry out all the quality analysis on the grain to make sure that the grain that we're seeing on our weighbridge is the grain that we've contracted from the farmer and to make sure that the grain is going to grow in our maltings when we actually get to the point of processing it at some point in the future. Chris - When you drink a single malt, what goes into that, is it a huge great collection of different barleys that you've started with or do you work in a strict batch? This is one farm, one batch process. Richard - We would contract with a number of our farmers. So around about this site we probably have about a hundred farmers. We contract certain varieties at certain quality parameters, and then we will bring those in at roughly the same time to then fill up some of the bins that you saw behind us. So we might fill up a 2000 tonne bin with maybe 20 farms of the same variety, the same quality parameters, and we will then process that bin for our customers thereafter. Chris - So what happens now? You've got a batch of barley, you say it passes muster. What's the next step?Richard - So after the intake process, we put the barley into our stores and then we recover the barley and make sure that the barley is going to grow when it gets actually into our steep tank. So in the UK we have a very light amount of dormancy in our grain. So it probably grows six or eight weeks after harvest, and then we'll take it to our steep tanks. And the steeping process is the first phase of the malting process. That's where we're going next. Richard - It's going to be hot. Okay. We'll literally only be in there for a minute then. So we've come up to the first phase of the malting process, which is steeping, which is where we take our raw barley and we add moisture, which initiates the biochemical processes within the grain. Chris - That's germination, isn't it? You're starting it growing. Richard - Exactly, so the barley grain is effectively a seed that we are commencing the germination phase of. Each and every one of the millions and billions of seeds in every batch that we make. So we need to add moisture and the steeping process is how we do that. Chris - Why do you need to germinate it? What does that do that is useful to yielding and releasing what's locked up in that seed?Richard - The barley grain is starch globules covered in protein. And there is some enzyme there, but it's very low levels. And what we do in the steeping process is hydrate the endosperm. We initiate all the enzyme potential and increase those enzymes and then those enzymes will then break down the protein and they will break down the cell material. So at the end of germination, we have got a much smaller level of proteins. The starch is there, but it's now released from its bound protein matrix that it was in as barley. And the enzymes are all around about the starch. And at that point we put it in our kiln, which is effectively a big oven, to then dry it down and fix that enzymic protein and starch mix that we have created. Chris - I think I need to grow a bit to see into these tanks, but they're enormous. They must be about four or five metres across these big circular tanks and I can see damp grain in there. Richard - Yeah, so this batch has been in here for roughly 24 hours. We steep in a new batch every day and this batch will be in these tanks for two days. So we've got another set of steep tanks just through the wall there as well. Chris - I can see water dribbling into one of the tanks next to us. So basically you put 28ish tonnes or whatever of barley in there and then half fill it up to just soak the grain and then drain that off. And you just repeat that a few times, do you?Richard - Yes. So we repeat that one more time. So there's the first immersion where we put the grain in and then we fill the water to just above the grain bed so that all of the grain is homogeneously covered in water. And then we rise it a bit to make sure, again, that it's all well mixed. And then that first wet phase might be six or eight hours and then we'll drain it off. And then that's an air rest for, it could be 10 hours. And then we'll again fill the tank with water above the green bed for maybe another six or eight hours. And that second immersion should take the moisture level from the initial starting point of 12% up to say 44% moisture. And then there's a small air rest at the end until it's ready to move to germination. So we'll go to one of the four germination vessels that we have on site. Chris - Hopefully it's a bit warmer because it's a bit chilly in here. Richard - It's definitely warmer. Chris - They're tall, those tanks, aren't they? Because we've just come down all the stairs that correspond to how tall they would've been. So they're quite big. Richard - Yeah. So I think the green bed is around about three metres deep in those tanks. Chris - And the conveyors will bring what we were just watching once it's had its immersions, they'll bring it over here. Richard - Yeah. So they'll take the fully steeped grain. Damp barley effectively that started its germination process. So it's 170 tonnes of that grain along the rubber conveying belts that you can see behind us into the vessel. And we'll load this vessel in about three hours and then we'll look after it in here for four days. Distillery ready: germinating and kilning barleyRichard Broadbent, Bairds MaltKeeping the conditions just right is the challenge for malting barley in the quantities processed at Station Maltings. . . Chris - Oh my goodness. You weren't wrong, were you, when you said it'll be warmer in here. It's like a hurricane force wind of hot damp air coming out the door. Richard - Yeah, so we maintain the temperature level in here around about 16 degrees centigrade air on, and maybe 18 or 19 degrees centigrade air off. So hence the nice warm feeling that we got coming through the door. Chris - This is a bit like the ring in a circus. It's that sort of size, isn't it? The floor is a whole heap of barley and you have a device that effectively stirs it and spreads it out as though you are spreading sand around the floor of your circus ring. And how often do you turn it over then to mix it up?Richard - So this turning machine that you can see in front of us actually moves very slowly. It takes around about three hours to get a full circumference of the vessel. So we make sure that we keep the vessel turned a couple of times a day anyway. And that keeps the rootlets from matting together. It allows the air that you can feel coming past us to evenly flow through the bed. And effectively what we're doing is replacing the air, which is around about the grain. So it's respiring, it's taking in oxygen and producing CO2 much as we would. So we are using large amounts of air to replace the oxygen and also control the temperature to the setpoint temperatures that we're after. Chris - How long will it stay in here?Richard - So we germinate and heat these vessels for four days. And that is the perfect amount of time to break down the proteins as we need to and generate enough of the enzymes for our customers to use in their process later on. Chris - And then where next?Richard - So from this germination vessel, we'll go to the kiln. It's going to be very hotChris - Good grief. Not even in there yet. You have to pay a fortune in Finland for an experience like this, you know, Richard. Good grief!Richard - We don't take tourists in here, for sure. Chris - How is the heat produced? Is this gas or electricity?Richard - Currently this is gas. Chris - It's incredibly hot. I mean that's sauna temperature. That's really, really hot. What's your gas bill like?Richard - It's huge. Yes, it's absolutely huge. Chris - The current economic climate must have made that even trickier. Richard - Yes, it has. It's made our products more expensive. It's made the beer that everybody buys in the pub or the supermarket, it has made that more expensive and it's made the whisky, which is being laid down for the future, more expensive as well. Chris - For people who didn't get to experience the sauna. It looked pretty similar to where we just were, except that it was 9 million degrees. It was really, really hot. But it's basically the same thing. You've got a thinner bed of malt and you're turning that for a period of time and you're just drying it out. So how long will it spend in there doing that?Richard - Our heating process, our burn process, is about 19 hours. And then there's the filling and emptying as well. And that allows us to take the moisture maybe from about 40% going in, reduce the moisture level down, and then start to build the temperature up towards the end of the process, which we just felt there just now. And those latter stages, they start to create the flavour and colour compounds and also fix the enzyme potential. Holds those enzymes in stasis for the onward processing at brewing or distilling phase. Chris - So despite the extreme heat in there, the enzymes in the grains do remain viable and intact. And when they go to the brewery or the distillery, they will reactivate, reanimate, and start to break down the seed. Richard - It's absolutely imperative that we give the brewer and distiller a high degree of enzymes as well as the starch, which we're giving them. So the brewer needs the starch to then convert into sugar. But to convert it into sugar, it needs the enzyme. So we need to give them a high level of enzymes as well. And of course, once the brewer, say, has converted their starch into sugar with the enzymes, that's when the yeast can then utilise the sugar to convert into alcohol. Chris - Where does it go next after it's been dried?Richard - So we put it into our storage facility where we take a sample and we analyse it in our central laboratory in Arbroath. When we have a full set of analysis, we can then determine that it meets our customer specifications and we can then set it for delivery to one of our many customers from this site, either in the UK or abroad, along the lines of their schedule. Chris - And then next stop for stuff that comes out of here is your home hunting ground where you hail from. And that's going to be Scotland and the whisky industry. Richard - Yes, exactly. So the whisky distilling industry requires a very high quantity of malted products each year. Largely distilling malt, plain distilling malt, and a little bit of peated malt, which we produce for our customers in Scotland. Chris - Well, I've had a blast. It's been amazing to see this. And I started by saying I've stood outside this plant on that railway station and looked up at this for so many years and wondered what goes on here. And now I know. Richard - Well, I'm very pleased to be able to show you and allow your listeners to hear about what we do. You know, people don't really understand what it takes to get a pint of beer on the bar or a bottle of whisky on the shelf. Chris - Are you a Burns Night man?Richard - I definitely am. Yes. I'm going to a Burns supper in the outskirts of Edinburgh. Chris - Do you get some freebies? Will you be able to turn up with a decent bottle of stuff?Richard - Sadly, we don't get too many freebies from our customers, so, no. No, sadly not