O’ water; giver of life, provider of beer. Now, you probably clicked on this article thinking “I know what water is, why has this person written a whole article explaining water?” Don’t panic, this isn’t GCSE chemistry (although there is a bit of chemistry involved), because we’re discussing how water is used in beer – historically and today. Take it from an English graduate who has nightmares about retaking science exams, we’ll keep this simple.

Water, by nature, isn’t the most inherently exciting topic. Without it, beer would be dead in the water, and you’d be left with raw malt, leafy hops and yeast all piled up and dry – delicious. While water constitutes roughly 90-95% of the final beer, it rarely gets the love and attention of, say, hops or yeast strains – even malt. Brewers could use the freshest hand-picked hops from Yakima Valley, the most exciting house yeast strain, and carefully selected barley from local producers but, unless they pay attention to their water and treat it accordingly, the final beer will probably still taste off. Water is full of regional differences and quirks that help to accentuate certain elements of the beer; an IPA made with a water profile similar to Burton water will probably taste hoppier than one made with a London water profile.

When exploring water in beer, it’s important to stress the environmental side of wastewater in brewing and how brewers are working to reduce their impact. It’s estimated that every litre of beer produced is made up of 60-180 litres of water – from grain production all the way to brewing. In our climate crisis and all-too-common drought throughout the world, it’s vital now, more than ever, to stress the importance of minimising waste. Treat this article as your guide to all things brewing water; how it’s manipulated, its regional differences, whether it’s hard or soft, and what impact it has on the can you’re drinking now. If you’re lost already, touch up on the brewing process on our Beer 101 page here.

What is water?

Hopefully, it’s something you’re drinking plenty of every day. Water, put simply, is two hydrogen atoms and one oxygen atom, H2O – a chemical substance/liquid that is transparent, mostly tasteless, odourless, and is vital for survival of all known forms of life. We should all know this right? Cool, let’s move on.

Water and brewing…

While water can be boiled down to H2O, that doesn’t actually begin to explain how many trace minerals end up in the water we drink or use to brew with. We’re about to get a wee bit science-y here, but there are some fundamentals you need to wrap your head around if we’re going to start talking about regional water differences and brewing. If you’ve ever wondered why a certain popular Irish Stout tastes better in Ireland, or why a Pilsner might taste better in the Czech Republic, you might want to stick around.

If you pour a glass of tap water from the sink, chances are there are traces of hundreds of different microbes, minerals and other compounds floating around in your glass. This may sound disgusting, but it isn’t necessarily a bad thing as these minerals are usually added to make your water safe. In London, the tap water contains a higher level of calcium bicarbonate and other minerals than water in Pilsen, Czech Republic, for example, which is rich in calcium chloride – hard water vs soft water, high alkalinity vs low alkalinity. Water that’s high in mineral content is considered hard water, whereas water low in mineral content is considered soft water.

Most brewers, through a process of reverse osmosis or distillation, will start with pure water and then add minerals or salts to achieve a certain water profile. There are loads of different potential minerals in water, but the key ones we need to understand for brewing are calcium, sulphates, magnesium, sodium, bicarbonate and chloride.

For brewing, calcium is often considered the most important chemical to manipulate. Calcium is vital for yeast flocculation – put simply, calcium rich water ensures that the yeast drops to the bottom of the fermenter when it’s done bubbling away, as opposed to remaining in the final beer.

Sodium is a simple one as it’s just a scientific name for salt. Salt doesn’t add much in terms of affecting how the beer is brewed, but it will make a difference to the taste and mouthfeel. At the end of the day,

salt is a flavour enhancer in food and drink, but you’re most likely to find higher levels of it in Gose style beers; a traditional sour style that’s brewed with salt and coriander.

Some magnesium is found naturally in malt, but brewers often top it up to achieve a desired flavour profile. At low levels, it can add a touch of bitterness – desirable in something like a West Coast IPA – but high levels can result in unwanted astringency. There’s also evidence to suggest it helps yeast metabolise (eat up) sugars during fermentation.

One of the most important minerals brewers manipulate for beer is bicarbonate content. Bicarbonate has a big impact on the pH level of the final beer – whether it’s more alkaline or acidic. In brewing, it’s used to counterbalance beer that’s becoming too acidic as bicarbonate is inherently alkaline and raises the pH level. Generally speaking, bicarbonate is either avoided or taken out of paler beers but added to dark beers to counteract acidity.

Chloride boosts softness and fullness in the mouthfeel, meaning it’s become very prevalent in modern brewing with the rise of hazy IPAs. Traditionally, it was used heavily for malt forward beers, but most brewers now associate it with NEIPAs. Sulphates are almost exclusively known for accentuating hop flavour and hop bitterness - too much sulphate, however, will result in unpleasant harshness.

Regional water profiles and how it affects beer

No matter where you are in the world, the water you drink, and the water used in beer, will be different to somewhere else. This is down to a few factors such as the actual source, the water treatment, and how the water has interacted with its environment over time. Differences in water profiles have led to the development of certain styles of beer that are uniquely tied to a particular region; however, when designing a recipe, brewers will still alter their water to more closely resemble the water profiles of these regions. Here’s a breakdown of popular water profiles that brewers often try to match or go off of when brewing…

Burton water is probably the most famous water profile in brewing as it’s closely tied to the invention of Bitters, Pale Ales and IPAs. The water in Burton-upon-Trent is famous around the brewing world; its high sulphate content is great for amplifying hop flavour and bitterness, and its calcium content is known for producing a clean tasting final beer. West Coast American water is also very similar in sulphate and calcium content to Burton, giving brewers in the 1970s the tools they needed to showcase US grown hops and kickstart the craft beer movement.

Sticking to the UK, London water is also historic in the making of porters and stouts. London’s alkaline rich water is full of calcium and bicarbonate, making it ideal for extracting colour out of darker malts and balancing the mash pH, resulting in delectable dark beers. Our neighbours in Dublin also have a very similar water profile to London but with less sulphate content, meaning their dark beers generally have less hop bitterness. Dublin stouts are known for being smooth, and I imagine everyone can think of the famous example of this.

Edinburgh has a similar water profile to London too, but with a higher alkalinity, meaning sweet malty beers were a mainstay of beer culture in Scotland – think Wee Heavy’s. Brown Ales and Mild became popular in the West Midlands due to the slightly softer water than the rest of the UK; high in calcium chloride, the water around here provided a softer mouthfeel and accentuated smooth malt characteristics.

Speaking of soft water, Czech water is perfect for brewing the Pilsner-style Lagers that eventually took over the world. Czech water is low in alkalinity and minerals, meaning it’s incredibly soft and perfect for showcasing bready, pale malts and a mellow hop bitterness. The only noticeable mineral is calcium chloride which, again, leads to a softer profile. The water in Dortmund, Germany is remarkably similar, but with a higher chloride content which promotes the sweetness of the malt and provides fullness. Vienna-style Lager originally tried to replicate the stuff from Dortmund, but their water was lower in calcium, chloride and sodium. When breweries in the city decided to add some toasted malt, it was a match made in heaven. The toasty notes of a Vienna Lager are complimented by its water – the lower chloride levels making for a crisper final beer.

The last famous historic water profile includes Munich water. Munich water has very low sulphate levels and higher alkalinity, meaning it’s perfect for big, malt forward Lagers, often with darker malts – think Dopplebocks, Dunkels and Märzens. Even the Munich Helles, benefits from this water as the higher chloride levels boost the softness of the malt and downplays the hop harshness.

It’s not historic, but we’ll give it a mention as they’re so popular; New England IPAs have a very distinct water profile that brewers manipulate every time they make one. NEIPAs are known for their soft body and low bitterness levels, and this is amplified by the water as brewers will add lots of calcium chloride to the water.

These regional differences are tied up in the history of beer and the development of certain styles. Today, brewers still use these historic water profiles as a base for creating a recipe, and often purify and treat their water to reach desired profile – especially important for cuckoo or gypsy brewers who move around from place to place. Water doesn’t do everything in determining the flavour or body of the beer, but it’s vital to understand some of its differences as good water treatment will turn a good brewer into a great one.

Brewing water and sustainability

The beer world has a sustainability problem. Between using countless litres of water for every batch of beer, flying fresh hops over from America, the electricity fermenters use to keep running, importing out-of-season fruit from different countries, or even putting malt in bags that aren’t recyclable, the beer industry’s carbon and waste output is hard to ignore. Luckily, there are some brewers leading change in the industry – especially when it comes to wastewater in brewing.

Not only are Jon and Jen Kimmich from The Alchemist brewery in Vermont credited for inventing the New England IPA, but they’re leading the industry again in reducing wastewater in brewing. Their wastewater is sent to a local college which has a system by which their power is generated from the wastewater. The Alchemist places a lot of thought into their environmental impact, and they’re encouraging more and more breweries to take a more sustainable approach.

Closer to home, Good Things Brewing Co. in Sussex is absolutely smashing it out of the park; they’re the UK’s first closed loop sustainable brewery. From boring their own water out of an underground well, to filtering their wastewater through reed beds (over time going back into the same well they got the water from!), to being fully solar-powered, transporting their beer in a solar powered van, and drying their grain and converting it into flour for local bakeries and pizza restaurants. Good Things are doing good things for planet Earth and have clearly put a lot of effort into their process – they also make damn fine beer, too. Freedom Brewery is another brewery that uses water from a natural well source and filters it through reeds back into the wild – on top of having beehives at their remote, countryside brewery.

These are just a few examples of craft breweries doing their bit to become more sustainable, and we’re going to continue shouting about sustainable breweries in our newsletter. Reducing wastewater is a significant way breweries can reduce their ecological impact as, while our planet is mostly water, only a small percentage of it is actually drinkable. As consumers, we can help do our bit; buy local, buy independent, and buy sustainable. While we can have many pints of beer, we only have the one planet.

Start your beer journey and check out our range of IPAs all brewed by indie breweries here

If hops are the headline act and yeast is the cool, unsung cult hero of beer, then malt and water are definitely treated as the supporting acts – they don’t get the attention they deserve, despite the vital role they play in brewing and the flavour of beer. For a product made up of only four main ingredients, every part is crucial to the process. If the final beer is an orchestra, malt is like the bass section; underappreciated, but it adds depth and it’s very noticeable if something is wrong. Without malt, beer would be an unfermented, sludgy, yeasty hop tea – tasty. Malt not only provides the sugar for the yeast to ferment into alcohol, but it also mostly determines the beer’s colour, body and flavour. If it’s so crucial to the making of beer, why is malt overlooked in the modern brewing scene?

There are a few potential reasons. Unlike hops, where new varieties are coming out every year and being cross bred to create whacky, exciting flavours, malt has been around for a long time. Humans have been harvesting grain (be it barley, wheat, rye or oats) since forever ago. Malt is an ancient institution, and the toasty notes of a Munich malt doesn’t sound as exciting as the creamy, coconutty, lime flavours of new US imported Sabro hops, for example. While some beer cans might list what kind of malts they use, many breweries don’t.

We’re here to demystify malt – the true underappreciated element of good brewing. Use this article as your guide to how malt is made, used in beer historically and today, types of malt and their flavour profiles and more. If you’re feeling lost already and want to touch up on the brewing process, check out our Beer 101 page here. With all that said, let’s go against the grain (pun intended) and talk about the bedrock of all beer: malt…

What is malt?

A simple question with a simple answer; malt is germinated cereal grains such as barley, rye, oats, wheat and spelt, that have been dried out in a process called “malting” – should be easy enough to remember. Before we get deeper into how malt is made, we should go over a bit of malt’s history.

The history of malt (and beer!)

To dive into the history of malt is to explore the history of beer itself. It’s believed that barley was first domesticated around 10,000 years ago, and the first evidence of beer being brewed dates back to roughly 7000 years ago in ancient Iran. The discovery that sugars in cereals can ferment is vital for the story of human survival as it allowed ancient peoples to not only drink something that was safe, but to also make bread – yep, sourdough is more than just a lockdown trend. The Ancient Egyptians, in particular, were known to be big beer drinkers. 

When they weren’t building pyramids, they were cultivating cereals and developing early brewing technology; no, it wasn’t aliens that built the pyramids, there’s strong evidence to suggest it was grain farmers in the off season. Beer was part of the Egyptians daily diet and was made from leftover barley bread, meaning the grain would have had that toasty flavour we associate with some malts today.

Skip forward a few thousand years and malt is commonplace in brewing all around the world; by the late 1500s European settlers in North America were making beer from malted maize/corn, and by the mid 1600s a new malting technique was about to change beer forever.

Before the mid 1600s, most grain was turned into malt by drying it in direct sunlight or, more commonly, roasting it over wood or peat fires – this often imparted a smoky flavour to the malt and the resulting beer. Old techniques like this are still used today in the making of Rauchbier, a traditional German Lager style known for its smoky malt character. This more intense roasting process also meant that most beer was darker in days of yore.

It was the use of coke, a fossil fuel that powered the iron and steel industries in England, that gave us beer how we know it today. Coke has a higher carbon content than wood or peat, meaning the heat it produces is “purer” or, in terms of producing beer, less smoky. The use of coke in malting was the first example of controlled production in making lighter toasted malt – thus, pale malt was born. It wasn’t until 1703 where we first see the term “Pale Ale”, but this less smoky and lighter beer began to catch on. The kilning advances made around this time coincide with the invention of countless new styles of beer, but it wasn’t until October 1842 where pale malt began to take over the world.

In the small town of Pilsen, Czech Republic, 1838, the townspeople were particularly unsatisfied with the local brewery’s beer output this season; and, in protest, they dumped most of it down the drain. Things had to change, so the townspeople threw together some resources and set up a new brewery to make sure the beer tasted better from now on – they even went as far to hire renowned Bavarian brewer Josef Groll, who had been wanting to try out some paler malt in a new beer. This combination of traditional Bavarian Lager brewing techniques with paler malt created something magical: the world’s first pale lager, what we now refer to as Pilsner (Urquell). Its clean, bright and golden colour caught on and became more fashionable to drink than the darker stuff, especially considering this invention coincided with the rise of glassware. Every modern pale lager is a variation or reaction to this original Pilsner style.

From this, malt cultivation and controlled kilning has become an institution. Around 1400 million hectolitres of beer are brewed a year worldwide and all of them, in one form or another, will contain a type of malt. Malted grain is the life-source of beer and without it we would be living in a dark parallel, beer-less world. The stuff of nightmares.

How malt is made and used – from farm to fermenter!

Now we know the importance of malt through time, it’s worth briefly discussing the elusively named process of…malting. While no one seems to question how the grain arrives in the brewery, it’s a pretty cool process that’s not too tricky to get your head around. So, here’s the journey from which a kernel of barley becomes beer….

Grains like barley are grown in fields, harvested and then sent to the malter. The barley is then steeped in some warm water where the germination process is kickstarted – for those who don’t remember any biology from school, germinating is when a seed/kernel begins to shoot and grow. It’s this germination process that converts the starch from the barley into fermentable sugar, and is typically done in big, humidified warehouse spaces. Before the sprouts can really start to grow, the barley is transferred to a kiln, where it’s heated, and dried.

It’s the kilning process that determines most of the barley’s colour and flavour: kilning at lower temperatures for a shorter period of time results in paler malt with more biscuity, caramel flavours; kilning at higher temperatures and for longer means darker malts with more roasty, savoury flavours. The malt in its various forms is then packaged and sent off to breweries – and that’s the entire malting process in a nutshell.

When brewing, malt is first milled (or, crushed) so the sugars are easier to extract. Malt is then mashed – this is basically the beginning step of all beer and is akin to the brewer making a very large batch of porridge. The malt is stepped in hot water for usually over an hour to extract all of its sugars for brewing. If the beer is mashed at a lower temperature such as 62C, then the resulting beer will have a lighter and drier body; if it’s mashed at a higher temperature such as 70C, then the beer will have a much fuller body and will be a bit sweeter. Mashing at higher temperatures creates long-chain sugars which are more difficult for the yeast to eat up, meaning there is more residual sweetness in the final beer. After mashing, the liquid (aka, the wort) is filtered out and transferred to the kettle where it is boiled, and the malt is disposed of. Fun fact: many brewers send their used malt to farms where it is often used as animal feed.

Types of malt

The undisputed king of beer malt is barley. Even so called “wheat beers” are rarely made with less than 30% malted barley. Barley is the key malt brewers use for a number of reasons; not only do barley husks provide a natural filter when brewing (making it easier to brew with), but barley has a unique set of enzymes that put it a notch above its other cereal counterparts. The structure of barley kernels and its enzymes break down much easier than other grains, meaning it can convert its starch into fermentable sugar more efficiently. More sugar = more beer = a good thing.

Historically too, barley is an easier grain to grow as it thrives in different climates and requires less nutrients in the soil. We won’t get too technical, but barley in beer comes in two main forms: Six row barley, which is considered more economical but less flavourful and is often used in commercial brewing; and Two-row barley which is more flavourful and more often used in craft brewing. Two-row and Six-row aren’t mutually exclusive to micro and macro beer, and brewers can use either to achieve a desired result.

Malt is often split into two main categories: Base and Speciality. Your base malts are pale or lager malts that will constitute most of the mash in the beer, even the darkest of all stouts will only contain around 10% dark malt. The most popular pale malt is Maris Otter, which is biscuity and nutty, and the most popular types of lager malt are Pilsner and Munich – both are clean and sweet, but Munich is known for having a toastier, bready edge. Your speciality malts are everything else that is not a pale, base malt: crystal malt which is caramelly and provides an amber colour; amber and biscuit malts which are toastier and provide deep biscuit and toast flavours; and roasted malts which are near black and can impart a bitter chocolate and coffee flavour. There are hundreds of variations that will give off all sorts of flavours and colours, meaning the type of malt a brewer uses is as important as hops or yeast when it comes to overall taste and (especially) appearance.

Every other type of malt is considered an Adjunct; it sounds like a bad thing, but it simply refers to any source of fermentable sugar that’s not malted barley and some types of malted wheat. Speaking of which, wheat is the second most common of all malts and is associated heavily with styles of Wheat Beer – never would have guessed. Wheat in beer comes in two main forms: malted and unmalted.

Malted wheat is similar to barley in that it doesn’t have that sticky outer husk that gets stuck in brewing filters. However, it differs in its protein content. Being much higher in protein, malted wheat gives beer a silky mouthfeel, great head retention and a slightly hazy appearance – this means malted wheat has become a common ingredient in New England IPAs alongside traditional Wheat Beers. Unmalted wheat is the one that’s considered an adjunct and is used much more sparingly due to its very high protein content. Unmalted wheat is traditionally used in lambic brewing as its complex sugars are harder for traditional beer yeast to break down but is suited to wild strains like Brettanomyces.

These days, oats are bloody everywhere in beer – or at least in most hazy beers which dominate the market. From popular NEIPAs to Oatmeal Stouts, oats are known in brewing for one thing: soft mouthfeel. Oats, like wheat, are high in protein, but don’t add much overall sweetness. A beer brewed with plenty of oats tends to have a super hazy appearance and a silky-smooth mouthfeel and body. Although it has been done before, brewing with 100% oats is considered a ridiculous endeavour as oats are notoriously sticky in the mash – oats usually make up a small portion of the grain bill for this reason.

We’ll skip through the last couple as they’re not as common. Rye is delicious but is used predominantly as a complimentary addition (like oats) and gives the beer a slight, dry spice note. Rice is also a complimentary addition to the mash and is famously used in a beer we shan’t mention by name but rhymes with “be wiser” (and support independent breweries). In the malt bill, rice doesn’t add much flavour but can be used well in making beer taste light and clean. Corn is traditionally used in lighter styles such as American Pilsners and Cream Ales as it gives the beer a lighter colour and results in a drier, light flavour.

All in all,

Malt is as diverse, interesting and impactful as any other ingredient in beer. We should be paying attention to malt in the same way we do hops or yeast strains as, without it, we wouldn’t have beer. Grain and malt have played such a vital role throughout human history, let alone brewing; so next time you pick up a can of beer, pour it in a glass, pay attention to the beer’s colour, take a sip, and think about what malt flavours you’re picking up. Is it a toasty, nutty bit of pale malt? Is it a roasty coffee note? A bit of biscuit? Ignore the hops for a second and allow your mind to explore the wonderful world of malt.

Start your beer journey and explore our range of Lager here

Without yeast, beer wouldn’t exist. Yes, you read that right; a universe without yeast would mean a dark, dystopian parallel world without beer. While beer is made up of malt, hops, yeast and water, yeast is probably the most crucial ingredient in beer, and without it you’d be left with an unfermented hoppy malt soup – sounds delicious. Put simply, yeast is the magic ingredient that makes beer, beer.

Yeast is about much more than just beer, too. This single-celled organism has been around since the beginning of life on Earth and laid the foundation of modern civilisation in regard to baking and fermentation – two things that allowed humans to eat food that was safe and free from harmful bacteria. We may be getting too broad here, but it’s vital to stress the importance of yeast and, in this case, yeast in beer.

Yeast is a bit of a rabbit hole topic and different yeast strains can give off all sorts of flavours; there’s endless science and complicated stuff surrounding it and how brewers use it, so we’re here to keep it simple. Treat this article as a guide to what terms you might see on modern craft beer cans – yes, by the end of this, you’ll know what mysterious terms like “Kviek”, or “spontaneous fermentation” mean. Before we get to all the stuff about different yeast strains in brewing, it’s worth understanding a little bit of history and science to better inform how yeast is used in brewing today – who knows, stick around and you might get a bit of pub quiz knowledge in the process. 

If you’re feeling lost already, it’s worth touching up on how beer is brewed on our What Is Beer page here

What the h*ck is yeast?

Yeast is a single-celled microorganism that is part of the fungus family – yep, yeast is a not-so-distant cousin to the humble mushroom. The word ‘yeast’ comes from the Old English word ‘gist’ and Indo-European root ‘yes’ meaning to ‘bubble’ or ‘foam’ – something yeast does during fermentation. While yeast has been around and unknowingly used for fermentation since Ancient Egypt and even before, it wasn’t till the late 1860s that microbiologist Louis Pasteur discovered that it was yeast that did things like give alcoholic beverages their alcohol.

While Pasteur deserves credit for finding out what fermentation was all about, it wasn’t until the 1880s when a man named Emil Christian Hansen (from then small local brewery Carlsberg) managed to isolate a pure yeast cell. It was after this later discovery that brewers really began to pay attention to isolating certain yeast strains to achieve control in fermentation and desirable flavours.

Before this discovery in the late 1880s, brewers would re-use or ‘pitch’ yeast from previous batches of beer to ferment all beer (something that still very much happens today). However, before yeast’s formal discovery, this re-pitching process was based more on superstition and observation. Brewers of yore noted that when they didn’t use the cakey substance found at the bottom of the barrel of the previous batch (the cakey substance being yeast), they wouldn’t have an alcoholic or tasty final product. Other tricks old breweries would employ were along the lines of simply reusing barrels and pots that produced good batches before – superstition over science.

This continuous reusing of equipment and cakey substance at the bottom of each batch is how we ended up with so many different cultivated yeast strains today. Many Belgian Trappist beers have been using the same house yeast strain for generations and generations, meaning the yeast has become incredibly distinct and characterful in flavour. If you re-use/re-pitch yeast from a previous batch of beer and add it to a fresh batch it becomes a ‘second-generation’ yeast; if you use it a third time it becomes a ‘third-generation’ yeast and so on. Many historic brewers have yeast that has been re-pitched so many times that eventually it becomes what is known as a ‘house yeast strain’ – you’ll see this pop up on beer labels a lot these days as more breweries experiment with sour styles, but even some hyped IPA breweries like Verdant have a house yeast strain now too.

What does yeast taste like?

The flavour profile of yeast varies considerably depending on the particular strain. There’s definitely an overarching scent it gives off which is often, unhelpfully, described as “yeasty” – a kind of freshly baked funky bready smell. Ale yeast tends to be a bit fruitier than Lager yeast, but we’ll get into that in a bit. The key description you need in understanding the flavour of yeast is the word ester.

Esters are what give yeast its complex, slightly fruity characteristics, and the flavour components of the esters depend on the strain. If you’re drinking a Bavarian Hefeweizen, it’s the yeast that gives the beer its distinctive banana and clove-like flavour; if it’s a Saison you’re drinking then the yeast is giving your beer an intense fruitiness with a hint of fresh spice and grass, whereas yeast in IPA tends to be in service of amplifying the hop profile and is more of a blank canvas in terms of flavour profile. There’s an endless variety of flavours for different yeast strains, and we’ll get further into its complexities and distinctions, but first…

The sciencey stuff

We’ll keep this brief but let’s run through a few scientific/brewing terms in yeast, just in case they pop up on the occasional beer label.

The by-product of yeast fermentation is alcohol: when yeast eats up sugar created when brewing, it creates ethanol, aka. alcohol in beer. If yeast is fermented under pressure it produces CO2 which then carbonates the beer – put simply, yeast farting under pressure makes your beer fizzy. Delicious.

If a brewer starts talking about something called “attenuation”, this is basically a jazzy way of saying how much sugar will be eaten up by the yeast. If the yeast has an average attenuation of say 80%, the resulting beer will be drier, lighter and less sweet than a beer with an attenuation of 70% as the yeast will have eaten up 80% of all sugar as opposed to 70%. Theoretically, this means that only 20% of sugar will be left in the drier beer, and 30% will be left in the sweeter one – more leftover sugar means a fuller mouthfeel. For example, New England IPAs tend to use yeast with a 70% attenuation rate, resulting in a sweeter, fuller body, whereas West Coast IPAs use a higher attenuating yeast around 80%, resulting in a drier, lighter body.

While you’re less likely to see the term “flocculation”, brewer’s use it all the time to describe what yeast does when it’s finished fermenting. Flocculation is basically how much yeast will remain in the beer when fermentation is finished – will the yeast make the beer hazy or not. Yeast strains used in New England IPAs or Wheat Beers have low flocculation, which means much of the yeast residue is left in the beer and makes the beer hazy. On the other hand, beers with high-to-medium levels of flocculation are more common, and the higher flocculating yeast strains are associated with cask conditioned beer and traditional ales.

Yeast strains: from Brettanomyces and beyond!

Technically speaking, there are only three categories of beer and it all depends on the yeast: Ales, Lagers and Wild Beer. All Ales, everything from Stouts, IPAs, Barleywines, and Wheat Beers, are fermented using a variation of Ale yeast: Saccharomyces Cerevisiae. Ale yeast is known as ‘top-fermenting’ yeast as it’s pitched at the top of the wort and often stays in suspension while fermenting. This type of yeast is most comfortable fermenting around 20C and is known for producing fruitier flavours than Lager yeast.

Speaking of which, Lager yeast, or Saccharomyces Pastorianus, is comfortable at much cooler temperatures around 11C and is known as ‘bottom-fermenting’ yeast. Lager yeasts have much cleaner and less fruity flavours than their Ale-y cousins, but they also produce less fusel alcohol flavours meaning the beer tastes less alcoholic. This is all very broad and there are endless variations, temperature differences and oddities that cross the boundary from Ale to Lager and vice versa, but this should give us a good understanding of the broad categories of beer. We’ll get into Kölsch another time.

What about the third category you ask? If you’re still with me then we’ve truly gone down the rabbit hole now, so let’s talk about Brettanomyces, or Wild yeast. Believed to originally have been isolated from beers in Britain – ‘Brett’ roughly translates to ‘Brit’(ish) – Brettanomyces is commonly associated with Belgium and is used heavily in many traditional abbey beers and Lambic brewing. Brett will eat quite literally any sugar, meaning its attenuation rate is around 85%+, resulting in lighter bodied, drier beer. Flavours produced by Brett can, in most brewing, be considered as off flavours; some have described Brett as funky, acidic, and tasting of a farmhouse-y wet sheep smell. However, in certain styles, Brett is unbeatable as it can produce some of the most complex, interesting flavours in all of beer.

In modern brewing, Brett is often used in conjunction with other wild bacteria strains like Lactobacillus – and this is called mixed fermentation. In fact, any combination of Ale yeast, Brett, Lactobacillus, and Pediococcus (a lactic acid bacteria), can be called a mixed fermentation beer. While it may sound spooky and complicated, mixed ferm is just a more technical term for mixing different types of yeast together to ferment a beer. Easy right?

There’s a lot of confusion around when discussing spontaneous fermentation, so let’s keep it simple. Spontaneous fermentation occurs when a brewer lets their beer cool overnight in large vats that are exposed to open air – this is most common in Lambic brewing as they use big shallow vats called coolships. Yeast, and even brewer’s/Ale yeast, is all around us; floating in the air, in nature, on fruit, attached to your body – everywhere. For the beer that’s being cooled down in open vats, this means that yeast from the surrounding area floats into the beer, infects it, and immediately starts fermenting the cooling beer. Think of biting into an apple: you take a bite, leave it out for 15 minutes, and the apple begins to rot in front of your eyes – a similar thing is happening with spontaneous fermentation.

There are hundreds of different types of microorganisms and yeast in the air, meaning there’s potentially hundreds of different types of wild yeast fermenting the beer – this means that spontaneous fermentation is, by design, a natural form of mixed fermentation as it’s impossible to say how many different strains of yeast are in the beer (unless you sent it off to a lab, but who has the time?). Spontaneous fermentation is one of the earliest forms of mixed fermentation. However, if you were brewing a Brett yeast IPA, for example, and so combining Ale yeast with Brett, this would be an example mixed fermentation but not spontaneous fermentation as the Brett IPA would not be cooled in open vats and be infected with other wild strains in the air. This theoretical Brett IPA would be made in a controlled environment away from the open air, and the brewer would pitch Ale yeast and an isolated Brett strain.

We could talk about brut beer, but their heyday seems to have been and gone so we’ll keep it short: brut beer is beer fermented with champagne yeast, resulting in a very dry, light and wine-like final product. It can be hit and miss.

Last but not least, we’ll go to the hype yeast strain of today: Kviek yeast. No one knows how to pronounce this Norwegian farmhouse strain. I’ve spoken to Norwegian brewers and even they don’t know – “quake”, “kiv-eck” or “k-vayk” are generally accepted, but I doubt anyone really knows for sure. While its pronunciation is shrouded in eternal mystery, Kviek is one of the more identifiable yeast strains in modern brewing due to its use in popular New England style IPAs. Kviek is an ale strain which, unlike most ale strains, can ferment at really hot temperatures – we’re talking up to around 40C, which is the average temperature of a hot shower in the UK. Madness. When normal ale yeast ferments at that kind of temperature, it’ll produce fusel alcohols which will make the beer taste similar to your hand sanitiser. Kviek yeast, however, does not produce any fusel alcohols at this temperature, meaning you’re left with a more intense fruitiness and a slight spice note to your beer. This beer has a crazy high flocculation rate but is often used in hazy IPAs to bump up the juicy flavour.

Out of the rabbit hole…

Phew! That’s a lot of info. Any article about yeast ends up far longer than you expect it to, but we hope this clears up a few things; at least now, if someone asks you the Latin name for brewer’s yeast in a pub quiz, you’ll know (Saccharomyces Cerevisiae).

We’ve hardly scratched the surface, but this article will give you a springboard to understanding what’s being talked about in brewing today. So, next time you’re scrolling through our fridges and looking at all the fancy beer labels, make sure to pay attention to the unspoken hero of the beer world: yeast.

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