Antioxidant activity in a set of sorghum landraces and breeding lines

Sorghum (Sorghum bicolor L) is becoming an increasingly important crop in the developed world especially as a cereal grain option for patients with celiac disease, being also characterized by a high level of bioactive compounds. It is a good source of phenolic compounds, including phenolic acids, flavonoids and condensed tannins, that express antioxidant capacity and potential health benefits. A group of 210 sorghum genotypes was evaluated in terms of physical parameters and resulted to be characterized by a wide range of 1000-seeds weight (6.93 - 42.67 g) and kernel colour. A sub-set of 121 samples were selected by near infrared spectroscopy for chemical analyses, and revealed a wide range of variability for total antioxidant capacity (6.89 - 172.02 mmol TE kg-1 dm-1), phenols (0.60 - 20.73 g GAE kg-1 dm-1), condensed tannins (0 - 28,362.63 μg CE g-1 dm-1) and flavonoids (0 - 8,138.22 μg CE g-1 dm-1). A high negative correlation was observed between antioxidant compounds and the colour parameters L* and b*; on the contrary, correlation of the same parameters with a* was low and positive. The results of these preliminary analyses highlighted genotypes characterized by light-coloured grains (white or yellow), large seeds, high antioxidant properties but absence of condensed tannins, all traits which make them suitable for food industry