The color of beer is measured using a scale called the Standard Reference Method (SRM). This scale allows brewers and beer enthusiasts to quantify and describe the color of different beers. The SRM scale is based on the attenuation of light, specifically a beam of light with a wavelength of 430 nm, which corresponds to a blue-violet color.
To measure the color of beer using the SRM scale, a sample of beer is placed in a container with a thickness of 0.39 inch (1 cm). Then, a beam of 430 nm light is passed through the beer, and the amount of light that is attenuated or absorbed is measured. The more light that is absorbed, the higher the SRM value and the darker the beer.
The SRM scale ranges from pale yellow or straw colors at the low end to deep, dark brown or black at the high end. It provides a numerical value to describe the color of beer, allowing for consistency and comparison among different brews.
The SRM scale is not only a useful tool for brewers when formulating recipes and achieving desired color profiles, but it is also important for consumers who want to understand and appreciate the visual aspect of beer. The color of beer can provide valuable information about the style, ingredients, and brewing techniques used.
Personally, as a sommelier and brewer, I have encountered a wide range of beer colors throughout my career. From light, pale lagers with SRM values around 2-4, to amber ales with SRM values around 10-14, and all the way to rich, dark stouts and porters with SRM values exceeding 30. Each color tells a story and contributes to the overall sensory experience of the beer.
It's worth noting that the SRM scale is just one aspect of beer color. Other factors such as haze, clarity, and the presence of sediment can also affect the visual appearance. Additionally, some beers may exhibit different hues or undertones depending on the ingredients used, such as roasted malts giving a reddish or coppery tint.
The SRM scale provides a standardized method for measuring and describing the color of beer. It allows brewers and consumers to communicate and appreciate the visual aspect of beer, enhancing the overall enjoyment and understanding of this versatile and diverse beverage.