Reflectance colorimetry as a simple method for estimating carotenoid content in maize grain

Abstract

Yellow corn grain is the only cereal containing appreciable amounts of carotenoids, compounds that can act as antioxidants, pigments or vitamin A precursors. Current methods for determining carotenoids in corn grain are costly and time-consuming, so the aim of the present research was to evaluate whether simple grain color measurement might serve as a fast, low-cost and reliable method for predicting carotenoid content. The six commercial corn hybrids were analyzed for carotenoid profile using HPLC and color parameters using reflectance colorimetry (CIE L*a*b*). The hybrids varied substantially in carotenoid content and color parameters. Levels of zeaxanthin correlated positively with redness (a*) and hue angle (hab), while levels of lutein, β-cryptoxanthin and β-carotene correlated positively with yellowness (b*) and chroma value (Cab*). The level of total carotenoids correlated positively with all color parameters except hab. Multiple linear regression was carried out in which scalar color coordinates (L*, a* and b*) and angular coordinates (L*, hab and Cab*) were considered independent variables, and equations with R2 > 0.9 were obtained. The results show that individual and total carotenoid content of corn grain can be accurately predicted using colorimetry, making it a fast and inexpensive method for carotenoid estimation in this crop.