Individual polyphenolic profiles and antioxidant activity in sorghum grains are influenced by very low and high solar UV radiation and genotype

Sorghum is becoming more widely recognised around the world as a valuable crop for its polyphenol antioxidant health-promoting properties and adaptation to harsh environments. The antioxidant capacity of diverse polyphenols in sorghum grain can vary with climatic conditions and genotype. To explore this further, the potential role of UV radiation on the profile and concentration of polyphenols was investigated in six diverse sorghum genotypes in a controlled environment facility using natural UV and visible radiation under either UV-transmitting or UV-blocking treatments. The polyphenol content and antioxidant activity were significantly reduced under the UV-blocking treatment, with contents of individual polyphenols differing among the genotypes. This information is valuable for sorghum breeders enabling them to select genotypes and UV growth conditions to produce sorghum grain with target levels of polyphenols and antioxidant capacity for human foods to meet the nutritional and health needs of different consumers.