The “What beer is made from” series is deep dive into beer’s four main ingredients and their impact on its flavour. New to the series? Start here.
Malt (aka malted barley) is the main sugar source used in brewing. But it also gives beer much of its colour and flavour.
(If you’re wondering why we need a source of sugar to brew with, learn more here.)
Malt is shorthand for malted barley, in other words barley grains that have gone through the malting process.
Barley is a grain that contains starches, which are long chains of sugars. But yeast can only ferment simple sugars or short chains.
So, the barley is put through a process called malting, so that its starches can later be converted to sugars during the brew.
Why does barley contain starches? They serve as energy reserves for growing a new plant. But they’re kept under lock and key until conditions are just right for germination. By malting barley, brewers can trick the grain into thinking it’s time to germinate… making those all-important starches accessible.
Before we get into the malting process though, let’s take a moment to discuss why barley is the perfect grain for brewing.
In addition to its starches, barley also contains proteins, which give beer body and help support its head of foam. (And importantly it doesn’t contain too much, as that would give the beer a hazy appearance.)
It also acts as a source of nutrients for yeast during fermentation and it has an outer husk, which helps with filtration during the brewing process.
While different types of barley do exist, like two-row and six-row, winter and spring, and plenty of individual varietals, like Tipple and Maris Otter, our focus here is on the flavour impact of malting and kilning, less so on the individual varietal.
So, let’s talk about the malting process!
The malting process
The malting process has three steps: the grains are soaked, begin to sprout, then sprouting is stopped by applying heat to dry, then toast, the grains. (If germination continued, the grain’s energy reserves would be used up by the new plant.)
It’s this final step that has the biggest impact on the finished beer.
The length of time and temperature in the kiln (where the grains are dried, then toasted or roasted) determines the colour, flavour and how much energy – or fermentable extract – each type of malt contributes to the brew.
Malt is broadly grouped into two categories based on how much fermentable extract it contains: base and specialty.
Base malts have loads of available energy reserves, but they also contain all-important enzymes that allow brewers to put this energy to use. (Enzymes are molecules that help speed up chemical reactions.)
As we mentioned, plant energy is stored as starch – a long chain of sugars. Yeast, however, can only ferment simple sugars, or short chains.
Base malts are not only rich in starch, they’ve also got the enzymes needed to convert that starch to sugar. (This conversion happens during the first step of the brewing process, called mashing, which we’ll discuss in the next series on ‘How beer is made’.)
Base malts are kilned at lower temperatures, which not only keeps their enzymes alive, but keeps these malts light in colour, too.
A few base malts to be familiar with are golden Pilsner malt, pale ale malt, and copper-coloured Vienna malt.
Specialty malts, on the other hand, are added just for colour and flavour, not as a sugar source. The high temperatures they are exposed to in the kiln destroy the enzymes needed for starch conversion.
But, these high temperatures produce a reaction, called the Maillard reaction, that creates some incredible colours and flavours… but we’ll come back to that in a bit!
Some specialty malts, like chocolate and black malts, are roasted. While others, the crystal or caramel malts, are stewed.
Produced by a special method, crystal malts are roasted when wet. The moisture plus the high kilning temperatures causes the sugars in the grains to caramelize. As these sugars are a bit too complex to be fermented by yeast, they remain in the finished beer, making it taste sweeter and feel fuller.
Generally speaking, base malts will make up around 90% of the total grain bill. The last 10% is a mix of specialty malts for colour and flavour, as a little of these goes a long way!
While malt is primarily a sugar source, I can imagine you’ve started to notice by now that it plays a big part in determining beer’s colour and flavour, too.
Flavour-wise, nearly all beers will have some sweetness from malted barley, but as most of malt’s sugars are fermented by yeast, beer should only really taste sweet if there is any residual, or unfermented, sugar.
That said, the flavour contribution from malt is largely determined by its colour:
- In straw coloured beers, like a Belgian witbier, we might expect to find doughy flavours, like bread dough or uncooked flour.
- Gold coloured beers, like a Czech pilsner lager, tend to have flavours of white bread or water cracker.
- Amber coloured beers, like American pale ales, often taste biscuity, toasty and caramelly.
- Brown beers, like the British brown ale, should have a range of nutty, toffee and chocolatey flavours.
- Finally, in black coloured beers, like Imperial stout, you’ll find roasted, burnt, or coffee-like notes from the dark malts used.
Many of these flavours, particularly in amber-coloured beers and darker, come from a reaction called the Maillard reaction. The chemistry is rather complex, but the main takeaway is that at higher temperatures, malt’s proteins and sugars combine to produce brown colours and toasted or roasted flavours.
Interestingly, these colours and flavours are also produced in other foods as they’re exposed to heat – like meats, bread, and coffee – hence why beers can have flavours so similar to food, and why beer works so well as a match for food! But that’s a story for another time…
For now, the main takeaway is that one single grain can give beer and incredible range of colours and flavours!
That said though, while malted barley is the main sugar source used in brewing, other grains can be used alongside it.
To get technical for a moment, any source of fermentable extract – other than malted barley – is called an adjunct.
Commonly used adjunct grains include wheat, oats, rye, rice and corn:
- Wheat has a higher protein content than barley, so it adds a fuller body and slightly hazy appearance to styles like German wheat beer.
- Similarly, oats add a bit of body and a smooth, creamy texture when added into an oatmeal stout.
- Rye also adds body and a hint of spice. It can really complement the hop aromas when added into an IPA, for example.
- Corn and rice are not used to add to, but to thin, the body styles like American Lager. They provide a source of sugar, without much additional protein, so the beer stays light and crisp.
- Brewers can also add sugar directly to their brews. This won’t sweeten up the beer, as the yeast will ferment it. Instead it increases the alcohol content and helps to lighten the body.
While malt largely determines a beers color, it isn’t the only contributor to beer’s flavour, texture and strength. Beer’s other ingredients – water, yeast and hops – all play their part.
Now, let’s move on to ingredient #2: water.