Why are Beers Different Colours?
The colour of beer is a clear way of telling one style of beer from another. For example, at one end of the spectrum, you have a pale lager, at the other, a dark, imperial stout. But between these two polarities, there are plenty of different beer colours and tastes.
Why are beers different colours, and how does this affect how beer tastes?
The Colour of Beer
The common colour of beer is red. Melanin is the rust-red pigment that colours grain and therefore impacts the colour of beer.
However, we know that many beers don’t appear red at all. What happens to change their colour?
The answer lies in two chemical processes:
The Maillard reaction, and
Caramelisation.
The Maillard reaction is named after the French physician and chemist, Louis Camille Maillard. He published a paper in 1912 that described the reaction between reducing sugars and amino acids.
What the Maillard reaction does is darken the colour of beer. This occurs when you link amino acids to sugars from the browning of grains.
What happens here is a similar process to browning a piece of toast. Maillard reactions create toasty flavours in beer, but because these reactions can occur at relatively low temperatures, you can also create a broad range of aromas and flavours.
Brewers can vary the duration and temperature of kilning to influence the outcome, creating a desired colour and flavour of brewed beer.
The other chemical process affecting the colour of beer is a simpler one. Caramelisation occurs when you heat sugar until it breaks apart.
The grain itself doesn’t contain sugar, but by wetting it, you convert the starch in the grain into sugar. Following this, you heat it to around 76°C. This develops the sugars in the grain. By increasing this temperature, you can then bake the sugars apart to caramelise them. The longer you do this, the darker they’ll get, producing stronger flavours.
A further method for producing roasted or chocolate malts is to kiln them at high temperatures to roast them to a black colour.
Timing is Important Too
Time is another factor in the colour of beer. Beer ages and as it does, the particles suspended in it fall to the bottom. The remaining beer reflects less light and so appears darker.
The ageing process also affects flavour, as the oxidation process takes hold. Some of these flavour changes are positive, but some can create negative perceptions of beer.
Perception is a significant factor when considering the colour of beer and how it might affect the taste.
How Does Beer Colour Affect Taste?
Colour acts as a visual cue for the consumer. Research shows that different visual appearances lead to differences in expectation when it comes to taste and flavour.
However, colour does influence flavour and, importantly for the consumer experience, aroma. Colour has more of an influence here than it does on the actual taste of beer.
But you shouldn’t underestimate the importance of a beer’s colour as a means of differentiation in the marketplace.
Colour, whether pale or dark, can be an important component of a beer's brand. It drives customer expectations and helps define a beer's identity.
The SRM Scale
SRM stands for standard reference method. This is a set of units that corresponds to the style and colour of different beers.
For example, pale lager has an SRM of 2, for a pale ale, it's 6 and a stout scores 29.
All beers travel in the same direction down the SRM scale. While they’re all red fundamentally, colour perception shifts, from washed-out yellows to opaque, dark browns.
Brewers can use grain to achieve the colour of beer they want, adding caramel or crystal malts accordingly. Caramel malts are kiln-heated, crystal malts are roasted. This distinction contributes to the different flavours in beer.
For example, light caramel malts add sweetness to beer. At the higher end of this range, you get more toffee or burnt sugar flavours.
However, some malts are also just used for colour correction, rather than to alter flavour perceptions.
How Do You Measure Beer Colour?
With so much at stake, brewers need an accurate way to measure beer colour, as well as other valuable properties. An excellent method is near-infrared (NIR) spectroscopy.
The Verum Analytics (not isochem) IsoChem Liquids NIR Analyser is a versatile instrument for measuring various critical parameters in beer, including colour.
It measures properties such as wort and fermentation and supports quality control of finished products.
With a sample process that’s fully automated, non-destructive and takes seconds to complete, this is the perfect answer to measuring colour in beer.
How Do You Test Colour in Beer?
In the brewing industry, NIR is a proven method for quality control of raw materials, but it also applies to testing the colour of beer.
Brewers face challenges in producing beers with identical flavour and colour profiles, batch after batch.
The IsoChem Analyser is suitable for both laboratory and in-line use, which means brewers can incorporate it into their production as a means of online process monitoring.
It’s designed for continuous, 24-hour operation and has a remote user interface with remote diagnostic capability. This makes it ideal for processing environments.
For more information about our complete range of specialist beer testing products, please contact us.