Recently the Beer Judge Certification Program (BJCP) released a beer Color Guide for use by all judges at BJCP sanctioned competitions. It is a 2.5 x 5 inch glossy card with instructions for use and is available for free to all current BJCP judges. This is a good tool and should help standardize perceptions of beer color at homebrew contests across the country.
The only problem with comparing beer color to a printed standard is that the appearance of actual beers is not consistent for a given value. In other words, you can have two beers that are visually different colors, ex., amber and copper, and these two beers can have exactly the same color value of 10.0 SRM. (In fact, the worts in Figure 1 above all measured 10.0 SRM) How can this be? The problem lies in the test method.
In 1950, the American Society of Brewing Chemists (ASBC) adopted the method of spectrophotometric absorption to measure the amount of light that passes through a standard-sized sample. The cause of the problem is that the particular wavelength of light they picked (430 nm) works best for light lagers. The darker beers (>10 SRM) that are common today are poorly differentiated by that wavelength, and can only be measured by careful dilution to allow enough light to reach the detector. (More information on beer color measurement can be found in my article, “Raise the Colors,” in Brew Your Own, May-June, 2003.)
Bob Hansen, of Briess Malting and Ingredients Co., brought these shortcomings of the modern method to light at the 2008 Craft Brewers Conference in San Diego. His presentation, “Beyond Lovibond — Understanding Beer Color,” is freely available on Briess’s website at http://www.brewingwithbriess.com/Assets/Presentations/Briess_2008CBC_UnderstandingBeerColor.ppt.
His presentation was a revelation to most of the brewers there, and certainly was to me. He explained the basis of the light absorption color measurement system, and revealed that there are basically two kinds of malts when it comes to color: kilned and roasted. The kilned malts include everything from base malt to Munich to amber to crystal malt (120 °L) — anything that has experienced a temperature of less than 325 °F (163 °C) during the malting and kilning process.
Roasted malts have experienced temperatures higher than 325 °F (163 °C) and they include chocolate malt, roast barley, and black malt. Another way to differentiate these malts is by the Lovibond color rating, where everything over 200 °L is generally a roasted malt. So, what is this difference between these two malts in terms of color? The answer is that below 325 °F (163 °C), the Maillard reactions predominately produce a color product known as chromophores. The color products from Maillard reactions above 325 °F (163 °C) are predominately melanoidins, and these two classes of compounds have different colors — and hence different absorption spectra when measured in a spectrophotometer. The chromaphore malt colors consist of yellow and red, while the melanoidin colors consist of more brown hues.
In addition, the high-color kilned malts have better antioxidant properties than the roast malts.
Effects on Beer Judging
Figure 1 shows different 10.0 SRM worts brewed with different malts. From the left, the first three malts are Munich (10 °L), Caramel 20, and Caramel 60 and these show an orange colored wort. (In the photo, these worts look slightly different. But, according to Hansen, the beers all looked identical and differences in the photo are likely due to slight diffreences in lighting.) The fourth wort from the left is made with Caramel 120 and, due to higher roasting temperatures, the malt contains a small proportion of melanoidins. As a result, the color of the wort deepens to red. The last two worts are clearly more a chestnut-brown color than red, and are made with roasted malts.
Figure 2 shows the same series of malts, but in worts at four different SRM values. All worts were measured down to one-tenth SRM. The rows are, from the bottom up, wort of 2.0, 10.0, 20.0, and 30.0 SRM. There is a clear visual difference between these two groups of malts that the standard ASBC color test measures to be the same. Thus, a beer that is brewed with a greater percentage of roasted malts is going to look visibly darker than the style guidelines would indicate, yet would still measure within the guidelines. I think that BJCP judges are going to need to keep this new understanding in mind when judging the amber, copper, and brown categories, and focus on beer flavor and allow for small differences in color if the flavor is appropriate.
Effects on Residual Alkalinity
For several years now, I have been preaching the virtues of understanding residual alkalinity (RA) — the key to understanding the mash pH balance between brewing water alkalinity and malt acidity.
In the mash, calcium and — to a lesser extent — magnesium push the pH lower. Alkalinity (from carbonates) resists this drop in pH. Residual alkalinity can be thought of as the amount of alkalinity “left over” after the effects of calcum and magnesium on the mash have been accounted for. When the mash pH is in the right range, and the fermentation is good, the beer pH will be in the right range and the beer will taste like it should. In practical terms, it means that if you have alkaline water and want to brew a pale beer, you need to add hardness (calcium or magnesium) to counter the alkalinity of the water. If you want to brew a dark beer in an area of low alkalinity water, then you need to add alkalinity to counter the acidity of the dark malts. You can add alklinity by adding either chalk (calcium carbonate) or baking soda (sodium bicarbonate) to your mash. Brewing a pale beer with low alkalinity water and brewing a dark beer with high alkalinity water works just fine because the malt acidity and water alkalinity balance each other.
But how do you know how much alkalinity or hardness to add? Well, that is where my RA nomograph and Mash pH Spreadsheet step in to help. (See Figure 3 on page 58 and also http://howtobrew.com/section3/chapter15-3.html for more information). Those resources make a correlation between RA and beer color that allows you to estimate a range of residual alkalinity that is appropriate for a recipe of a particular color.
To use the nomograph on page 58, you need to know the level of calcium and magnesium in your water, plus its alkalinity. Mark the points on appropriate number lines that correspond with your calcium, magnesium and alkalinity. Connect the dots on the calcium and magnesium lines with a straight line. Place a dot where this line crosses the “Effective Hardness” number line. Draw a straight line from this point, through the point on the alkalinity line corresponding to your alklinity and extend this line to the color bar. This will tell you the color of beer your tap water is most suited to brewing. It can also serve as a guide to making water chemistry corrections for beers in other color ranges.
There has always seemed to only be a general relationship between final beer color and malt acidity. And now, thanks to Briess’s work, I think I understand why. Looking at Figure 2 again, it is easy to see how a 10 SRM beer could be mistaken for a 20, and a 20 for a 30, and vice versa. It points out the problem of trying to predict how much residual alkalinity is needed to brew a recipe based on the SRM number listed on a brewery website or in the BJCP style guidelines versus the “perceived” color of a commercial beer.
I had noticed this in my development efforts years ago and compensated by specifying a range of 5 SRM for any particular value of RA, though looking at Figure 2, it may be reasonable to extend that to 10 SRM. Another factor to consider is predicting the beer color from the recipe. You cannot predict the final beer color simply from the malt color units of the recipe (a weighted average of the malts/Lovibond), because the actual color diverges from the MCUs once you get past 10 SRM. There are three popular color models that track this shift (Morey, Mosher, and Daniels) and the results for darker beers tend to be within 5 SRM of each other, so the potential error between models is not that large.
You should also think about the relative proportions of the two specialty malt types in the recipe to help you decide whether to choose the high or low end of the suggested range, instead of relying solely on the estimated color. For example, American amber ale (ex. 15 SRM) contains a lot of color solely from kilned specialty malts like crystal and biscuit making up about 25% of the grain bill. Contrast that with a robust porter (ex. 30 SRM) with about the same overall percentage of specialty malts (25%) except that total is split 50/50 between roast and kilned malts. Pound-for-pound, roast malts are more acidic than the kilned malts, so it would be logical to choose the lower end of the suggested RA range for the amber ale color (15 SRM = 60–120 RA), and the middle of the range for the porter (30 SRM = 244–303 RA). For a Russian imperial stout, with a color of 55 SRM, the spreadsheet calculates an RA range of 549–608. However, I don’t recommend exceeding 300 ppm as calcium carbonate (CaCO3), even for Russian imperial stout, unless you are monitoring your mash pH with a pH meter. The point is to not simply rely on the calculations, but to think and use your experience and intuition when formulating your recipe and adjusting your water. The flavor of your resulting beer will tell you if your experience and intuition were correct.
Fortunately, my recommendations for working with the nomograph and spreadsheet have not changed with this new information on malt color. Lots of brewers have used the nomograph and spreadsheet over the years and have reported success in beers they hadn’t been able to brew satisfactorily before. The purpose of this article was to make you aware that there are two different types of malt color, and to point out some of the ramifications of this to your brewing. Hopefully this has made you aware that there is a lot more to beer color than meets the eye.John Palmer is Brew Your Own’s Advanced Brewing columnist.