Color Analysis

Color is the first characteristic perceived by consumers and often the criterion with the greatest influence on consumer’s perception of quality, safety, and preferences. Therefore, food products must clear quality control specifications that must be carefully monitored and controlled. While subjective visual assessment and use of visual color standards are still used in the food industry, objective instrumental color measurements are extensively employed. This chapter provides a brief description of human physiology of vision and an overview of the different color-ordering and color-measuring systems, including visual and instrumental color measuring tools. Included are the CIE tristimulus system, tristimulus colorimeters, and spectrophotometers, with coverage of the Hunter Lab system and the CIELAB system (describing L*, a*, b* and L* C*ab, hab for color communication). We also introduce the use of advanced optical systems and digital imaging techniques. Finally, we present examples of how the food industry uses color measurements and discuss how the tools presented in the chapter can be used to assess food quality, shelf life, and meet tolerances. Also covered is sample preparation and presentation to get measurements that are repeatable and that better correlate to visual appearance.