Comparison of Antioxidant Activity of Barley (Hordeum vulgare L.) and Malt Extracts with the Content of Free Phenolic Compounds Measured by High Performance Liquid Chromatography Coupled with CoulArray Detector

Hot water (45°C) extracts of ten barley varieties and their corresponding malts were analyzed in terms of antioxidant activity. The ferric reducing antioxidant power (FRAP) and radical scavenging activity (ABTS), ranged from 0.23-0.45 mg GAE/gdw for malt and 0.12-0.25 mg GAE/gdw for barley. The hull-less malt KM 1910 was the variety with the best antioxidant properties, whereas the highest antioxidant capacity for barley was detected for the variety Merlin. A significant positive correlation between the methods FRAP, ABTS and ITT was found (p < 0.01). The influence of fertilization (20 kg N/ha) on barley antioxidant capacity was studied. The results obtained suggest that the impact of fertilization was not evident and that it depends significantly on barley genotype. The total polyphenol content, as measured according to Folin-Ciocalteu's method, ranged from 0.6-2.9 mg GAE/gdw and correlated positively with all the antioxidant methods used (p < 0.01). Free phenolic compounds were measured by HPLC with a CoulArray detector. The dominant phenolic compound was ferulic acid and its content ranged from 12.5–21.9 and 7.8–56.1 μg/gdw for barley and malt, respectively. The content of catechin ranged from 11.0–17.0 μg/gdw in barley and 0.9–12.1 μg/gdw in malt.