Colors of Beer: What are SRM and Lovibond?

colored beers

Brewers only have one chance to set the first impression of a beer as it pours into our glass. The color is the first indicator for what we want in a beer, based on the beer’s flavor. It covers an infinite variety of colors. Today we’ll learn more about the beer color:

  1.  How it’s measured
  2.  Color limitations
  3.  Estimation and limitations of the color of a beer recipe

How it is Measured

There are 2 methods used to measure the color intensity of the beer:
  1. SRM is a measure of the concentration of a beer’s colour. Measure in a path length cell for 0.5 inches (1.27 cm), with a wavelength shade of 430 nm. The resulting absorbance value is multiplied by 10 to obtain the color value by any dilution. The sample requires dilution to put the color within the spectrophotometer accuracy. If the length of the route is 1 cm (most spectrophotometer cuvette), then the multiplier would be 12.7 instead of 10.
  2. Joseph William Lovibond invented the Lovibond “52” in Greenwich, England. The visual comparison of standardized colors. (in the form of colored glass discs, with samples of beer.) A light golden lager may have a color of 2 or 3 on the Lovibond scale. Pale ale has a color of 10 – 13. Brown ale or dark lager has a color 17˚–20˚, all the way through to the near-black of imperial stout at 70˚.

Due to limitations with the way people perceive color, a new system was created—the Standard Reference Method (SRM) & European Brewing Convention (EBC). The SRM method contains the procedure of a spectrophotometer. It is to measure the light of a specific wavelength of 430 nanometers. It passes through a sample of homebrew contained in a cuvette. Then in the light path of the spectrophotometer. There is a lower SRM number for lighter values and a higher SRM number for darker ones. SRM values greater than 50 are considered black.

COLOR CHART:  Color Ranges
BEER STYLECOLOR RANGES
PILSNER2-7
Witbier, Berliner Weisse2-4
Belgian Strong Ale4-7
Maibock4-10
Vienna Lager7-14
Oktoberfest4-12
American Pale Ale6-14
Pale Ale5-14
English Golden Ale4-8
Bavarian Weizen4-10
Bitter, ESB8-14
Märzen7-15
Imperial Pale Ale5-11
Bière de Garde          6-13
Dunkel Weizen9-13
Amber Ale11-18
English Brown Ale12-22
Bock15-30
Porter20-40
Oatmeal Stout25-40
Baltic Porter17-40
Foreign Stout30-65
Imperial Stout50-80
CALCULATIONS: Estimation & limitations
  • The beer’s SRM color’s calculated using a 1⁄2 “glass cuvette. A spectrophotometer observes it at 430 nm of light wavelength. The SRM hue, which you can express on a logarithmic scale, is about ten times the amount of absorbance. In most cases, the SRM color is roughly equivalent to the old Lovibond scale. The other typical process’ called the European Brewing Convention (EBC). It is calculated in a smaller 1 cm cuvette but at the same wavelength, in action, the EBC color is around 1.97 times the color of SRM. (SRM = 1.97 * EBC)
Dan Morey Equation

You can use this equation in beer software to approximate color.

SRM = 1.4922 * (MCU ^ 0.68590)f

good for color < 50 SRM

MCU = grain color * grainWeightLBS / volumeGallons

A Malt Color Units (MCU) is the appearance of each grain times the weight of the grain in pounds. It’s divided by the volume of the batch in gallons. When using more than one fermentable. The color of MCU for each fermentable is measured and then applied together.

Note: Lovibond is used for malt calculation, while SRM is for the beer’s final color.

  • If you don’t have a spectrophotometer handy in your laboratory, some tools are available to help you measure the color of your beer. A beer reference color card is the most common and easy to use, to have a visual comparison of your beer against standard reference colors. I suggest you buy a guide from your local shop.
  • Another way is to dilute the beer with distilled water and compare it to established color norms ( such as mass-produced commercial beer)

Limitations of Beer Color and Color Estimates

No matter how precise your color estimate or calculation is. You need to remember that there are very real limitations to all current beer color schemes. The SRM color scheme is defined by absorbing a single wavelength of light. It can’t tell the difference between commonly colored red beers and amber beer. At a wavelength of 430 nm, the subtle shades of red and brown can look similar.

The specific color of a beer with a standard “beer darkness number” such as SRM can not be defined. In a single dimension, the slight variations in red, brown, black, copper, and straw can not be captured. Irish Red is a perfect example. If you do a color estimate on an Irish Red, you will possibly get something on the card that doesn’t look very red at all. Yet a tiny amount of roasted barley gives it the distinctive red hue that the SRM system simply can’t capture.

Extract brewers need to be aware that particularly liquid extracts tend to get darker as they age. And also, the extracts can darken when they boil in a cycle called caramelization. The net result of the aging and boiling effect is that many extract beers come out darker.

In practice, these issues are not a problem for the average homebrewer. Commercial breweries often use coloring agents. It’s a mix of batches and other techniques to achieve exact color matching from batch to batch. As a homebrewer, it is enough to know that a color estimate has limitations.

USING CRYSTAL MALTS / CARAMEL MALTS
  • Crystal malts are grains of specialty which add flavor and color to any brew. You can use these malts to manipulate the flavor of your beer. The sweetness of crystal malt has readily distinguishable caramel tones to it. Therefore crystal malts are often referred to as caramel malts. For several types of beer, the flavor of crystal malt is a significant attribute. (For pale ales and related styles most notably)
  • Crystal malts also add color to your beer. You can grade crystal malts according to their depth of color. It is normally measured in Lovibond (° L) degrees. Crystal malts range from 20 °L to around 200 °L, and the most common crystals are in the 30 ° to 40 °L range. Pale malts, by comparison, are usually rated between 1.5 ° and 3 °L. Rated chocolate malts around 350 °L. On the low end of their color range, they look only slightly darker than pale malts. As you move up the color range, they appear more reddish. The darkest crystal malts are nearly brown. A feature of how it was prepared is the color of the crystal malt.
Crystal Malts Recipe Formulation 
  • The quantity of crystal malt used can vary according to the beer type. Pale ales, bitters, or ESBs can contain up to 20 percent of crystal malt. Warehouses such as Octoberfests or lagers in Vienna can hold up to 15 percent of malt. Darker ales may also contain crystal malt along with more darkly roasted grains. E.g., porters and stouts.
  • You can rate crystal malts in degrees Lovibond. You can calculate how many colors you are adding to your beer. Calculation of the amount of color contributed by the crystal malt, use the following formula:

HCU = [color rating of grain (°L) x weight (lb) ]/volume of beer (gallons)

  • HCU stands for units of color in the homebrew. It has poor comparison with SRM. SRM stands for Standard Reference Method. It is the unit preferred by the American Society of Brewing Chemists for measuring the color of. For beers that measure from zero to 10, the two-color measures — HCU and SRM — are roughly equivalent. For beers over ten on either scale, the HCU value will be higher than the SRM value. A dark brown beer with 50 added HCUs will usually have a 20 SRM as a rough reference. Measuring actual SRM requires the use of a spectrophotometer.
  • HCUs only calculate how much grain you add to your beer. But many things that affect beer color do not enter into the HCU equation. For example, extended boil times darken the wort, and oxidizing hot wort will also darken it. In contrast, fermentation decreases wort color. Also, various mash/steeping conditions remove different amounts of color from the grain.
  • Another limitation of HCUs is that they only measure the amount of color, not the hue. So calculating HCU does not tell you everything you might want to know about color.

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