Carotenoid profiles in maize genotypes with contrasting kernel hardness

Kernel hardness is commonly related to total maize (Zea mays L.) carotenoid concentration. Based on the specific interactions between carotenoids and hardness related zeins, we tested the hypothesis that hardness is associated with the ability to store different carotenoids. Carotenoid profiles and flour color were measured in 13 flint and 5 dent temperate commercial hybrids, with known differential hardness and dry milling quality. They were grown in two environments during one season in Argentina. Significant genotype and environmental differences (p < 0.05) were found in all analyzed kernel hardness traits and total carotenoid concentration (11.85–28.68 mg kg−1). Kernel type (flint, dent) showed significant differences in the concentration and proportion of specific carotenoids. Flint genotypes had higher β-branch carotenoids (zeaxanthin, β-cryptoxanthin, and β-carotene), while dented hybrids had higher α-branch carotenoids (lutein, α-cryptoxanthin, and α-carotene). On average flint kernels had twice as much provitamin A concentration than dent ones. This had a direct impact on kernel flour color, flints yielded more saturated orange-colored flours and dents light-yellow colored flours. Our results support the concept that kernel hardness is an important driver for carotenoid profiles in yellow and orange temperate maize genotypes.