Dried Distillers Grain (DDG) is a cereal byproduct of distillation processes, usually from brewers, and fuel ethanol production. The byproduct is dried to give it a longer shelf life. DDG is sold as a high nutrient feed for livestock. The picture above shows four different DDG samples which exhibit visual differences from one another. Like most products, the color of DDG is directly linked to the quality.
High quality DDG is usually a golden honey or golden caramelized color, like that of the lower right sample. Darker colors of DDG are an indicator of poor quality and are a result of excessive heat during the drying process. When evaluating the quality of the DDG with color measurements the L* value from the CIE L* a* b* color scale is used as the primary indicator. Low L* values indicate that a sample is dark and of poor quality. Medium L* values indicate the ideal golden honey color of good quality DDG. High L* values indicate that the sample is too light and not of good quality.
HunterLab instruments are able to accurately measure the L* value of opaque non-metal samples, such as the DDG samples. By measuring the L* value, you are able to determine the quality of the DDG product.