Accurate technique for measuring color values of grain and grain products using a visible-NIR instrument

Measuring color is important when assessing grain and grain products as this has a major influence on the end-product quality. To objectively measure color, grain processors and plant breeding programs use colorimeters to measure L*a*b* values as defined by the Commission Internationale de L'Eclairage (CIE). In addition to color, most laboratories undertake other tests, often utilizing NIR (near infrared reflectance) technology. It is possible to improve laboratory efficiencies and remove double handling of samples by using one instrument, a visible-NIR spectrophotometer (400-2,500 nm), to measure color and other quality traits such as protein. In this study, we compared two techniques for measuring color of flour, barley, and lentils with a visible-NIR instrument. The first technique involved calibrating the visible-NIR instrument with colorimeter values using calibration models. However, calibrations are product-specific and require the development and maintenance of specific equations for each product analyzed. For the second technique, we calculated the color values from the visible reflectance spectra using the standard practice (E308) based on the CIE system. Our study showed the most accurate, efficient method for measuring the color of products with a visible-NIR instrument is to apply calculations using the standard practice based on the CIE system.