The effect of hull removal and pearling on Fusarium species and trichothecenes in hulless barley

Abstract

Fourteen samples consisting of three cultivars of hulless barley (Hordeum vulgare L.), grown commercially in southern Manitoba in 1994, were examined for levels of Fusarium species and seven fusarium trichothecene mycotoxins: deoxynivalenol (DON), diacetoxyscirpenol, 15-acetyldeoxyni-valenol (15ADON), fusarenone-X, HT-2 toxin, neosolaniol and T-2 toxin. Four fractions from each sample were analysed. These consisted of kernels with the hulls still attached, kernels whose hulls had been removed at harvest, kernels that had been dehulled in the laboratory using a deawner, and kernels that had been pearled in the laboratory to 60% of their original weight. A composite sample of the hulls, obtained from the laboratory dehulling, was also tested. Mycotoxins were determined by gas chromatog-raphy-mass spectrometry. DON and 15ADON were the only trichothecenes detected in this study. The greatest numbers of propagules of Fusarium spp. and the highest concentrations of DON and 15ADON were found in the hulls. The average concentrations of F. graminearum Schwabe and DON in barley were reduced: 90 and 49%, respectively, as a consequence of laboratory dehulling; 95 and 59%, respectively, as a result of dehulling during harvest; and 99 and 86%, respectively, as a result of pearling. Results suggest that growing hulless cultivars shows promise for management of mycotoxin problems associated with FHB. Key words: Fusarium graminearum, Fusarium poae, Fusarium avenaceum, deoxynivalenol, 15-acetyldeoxynivalenol, fusarium head blight