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Beer color - how it's defined
what makes it, what impacts it, and how to predict it ....
The following information has been extracted from a variety of sources including the Internet Homebrew Digest (#1328) and some recent personal correspondence. The source was invariably Dr. George Fix; except for a little editing here and there, my only contribution to the following was inserting references to Brewer's Workshop software for the development of recipes that include accurate color predictions.
Color affects the appreciation and evaluation of beer in subtle but definite ways. The color of beer can be a powerful but often subconscious generator of positive or negative response to the "brew in hand". A brew that "looks like it should" will undoubtedly taste better, if you know what I mean ... ?<g>? As a consequence, the control of brew color is important - it fits right in there with aroma, clarity, head, and other sensory turn-ons that contribute to the enjoyment of a tall cool one.
The ability to control the color of your brews is made a lot simpler if it is understood just how beer color is measured. There has always been a strong preference in brewing for visual units to be used for the evaluation and determination of beer color. There are many reasons for this, not the least of which is the fact that the classic beer styles are defined in part by definite visual images concerning what is appropriate. Beer and wort color traditionally have been measured visually, and early on the Lovibond (degL) scale was adopted as a standard. This scale consists of a well-defined set of color samples that are used for comparison. A visual match with a beer or wort sample defines the degL of the sample.
In the 1950s it was discovered that for pale beers absorbance so measured was essentially proportional to visual units like the Lovibond scale. In 1958, the American Society of Brewing Chemists proposed that the absorbance of beer in a 1/2" ID jar using a monochromatic light with a wavelength of 430 nm be used; the procedure was called the Standard Reference Method (SRM). They proposed a correction factor of 10 so the numbers reported would match up with the Lovibond scale. Commercial beer brewed at this time was almost always below 4 Lov., and hence SRM became viewed as an equivalent of Lov.
All is well - Lov. and SRM can be used interchangeably ... unless beer color moves into the amber regime at which time the relationships between visual and spectrophotometric units start to diverge sharply. Large commercial breweries continue to use spectrophotometry for color determination even for the amber and dark beers they started brewing in recent years. Their approach has typically been to develop new in-house correction factors for each of their brews which allows them to match up absorbance with the Lovibond scale within the range of variations seen in production.
So - homebrew is in hand - your looking at it admirably and wondering what color is it. You mean you don't have a spectrophotometer in your basement?? Don't despair!! For normal color determination, such as needed in recipe design and judging your homebrews, a little dohingy called the Davison Color Chart has proven to be quite satisfactory. This chart is actually a transparent film strip tinted at ten beer color increments between yellow (3 Lov.) to brown (19 Lov.). Most homebrew suppliers carry them or you can find them in their catalogs (about $7) - if all else fails, try calling 414-545-9246 which is a phone number provided with the strip's instructions. If properly used, errors will be at most 5% with this chart. The following table contains an intuitive description of the Lovibond scale which matches up well with the Davison chart.
Basic Color Hue Lovibond Units
light 2.0 - 3.0   medium 3.0 - 4.5   deepstraw/gold 4.5 - 6.0   deep gold 6.0 - 7.5
light 7.5 - 9.0   copper 9.0 - 11   red/brown 11 - 14
light 14 - 17   medium 17 - 20   dark - light black 20 - 25
start of full black >25
It should be noted that the visual units start becoming highly suspect once the full black regime is reached. For example, it is reported that highly qualified national judges have been unable to correctly distinguish beers at 40, 50, and 60 degrees Lovibond. A strong case can be made however that once a beer is in the full black regime, then flavor oriented issues should dominate the sensory perceptions of such beers - hey, black is black!
OK; so now we know what a 17 Lov. brew looks like - how do you make one ... ?? If you're using extracts, start your brew with a light extract and add steeping grains to adjust brew color (as well as for the inherent taste effects). Typical values for various malt types are shown in the following table ... the general properties of grains as well as their color properties can be found on my Grain Page
Malt Type Color degL U.S. two-row 1.4 - 1 8 U.S. six-row 1.5 - 1.9 Canadian two-row 1.3 - 1.7 Canadian six-row 1.4 - 1.9 German Pils (two-row) 1.6 German lager (two-row) 1.7 CaraPils 1.3 - 1.8 Wheat malt 1.6 - 1.8 Pale ale 3 Vienna 3 - 5 Light Munich 8 - 11 Dark Munich 18 - 22 Caramel 10 - 120 Chocolate malt 325 - 375 Black 475 - 525 Black barley 500 - 550
A rule sometimes used by homebrewers is that the color contributed by a malt is equal to its concentration in pounds per gallon times its color rating in degL. For pale beers this rule can give reasonable results. For example, 10 pounds of pale malt with color 1.6 degL in five gallons should produce a beer whose color is near
1.6 x 10/5 = 3.2degL.
For darker colored beers, this rule can give erratic results. Beers with an actual degL of 23 will be predicted at 70+ using the simple degL/lb/gal calculation. This is where Brewer's Workshop brewing software is invaluable (a link to the Brewer's Workshop website is on my OtherSites page. This little gem of a program includes a color calculator that is right on the money and the recipe printout will show you the individual color contribution of each component (note that the color units are incorrectley related to SRM - it should be Lov. The program takes into account the color rating of the components, boil/steep time, boil size/batch size, and spits out a number that matches reality as represented by the Davison Chart or the above table ... It's a great tool for recipe formulation when color is important. For example, you want to do a dark brown, but want to stay away from black/opaque - how much chocolate and or black patent do you add?? Just work up a trial recipe, do a print preview, check the color ... not what you want / too dark?? ... reduce the black patent by 2 oz. and the chocolate by 1 oz. .. ; a little trial and error but when you get what you want, save that recipe, print it, brew it ...
In the above discussion re. the prediction capabilities of Brewer's Workshop, I mentioned several factors that have an impact on brew color. More specifically, differences in a number of brewing conditions can lead to substantial color changes in the finished beer, these effects being particularly important for beers at 5 degL or less.
- Water: As the alkalinity of the water increases, so does the extraction rate of the coloring pigments in malt. The mash pH has the same effect, and increasing pH leads to worts with deeper color.
- Mash or Steep Time: Color increases with the amount of contact time with the grains. Thus, a prolonged mash (or steep) will produce a deeper-colored beer than a short mash.
- Kettle Boil Time: Wort color increases with boil time. A fact that is sometimes overlooked is that wort simmering has the same effect. The point is that this will lead to an incomplete hot and cold break, which in turn leaves more coloring elements in the finished wort.
- Hops: Some color is obtained from hops both in the kettle and in storage containers when post-fermentation hopping is used.
- Fermentation: The proteinous matter produced during the cold break is full of coloring materials and, hence, removal of these materials will reduce color. It has also been reported that color changes during fermentation vary with yeast strain.
- Filtration: This can dramatically reduce color. It should be noted that a clear beer will appear to be lighter color than turbid beer.
- Oxidation: At all stages of brewing, air pickup will deepen beer color. This is as true of hot wort production as it is of bottled beer with head-space air.
Hope the above information helps; may your next brew be a pretty one .. :-)