Fate of Ergot (Claviceps Purpurea) Alkaloids during Malting and Brewing

Abstract

Ergot, caused by the fungus Claviceps purpurea (Fr.) Tul., is a disease that can infect cereal grains, including barley. The presence of ergot sclerotia in harvested grain is regulated in many countries, because the sclerotia contain alkaloids that can be harmful to humans and livestock. Although the impact of thermal treatment on ergot alkaloids has been investigated in food-processing studies, there is no information available on the effects of malting and brewing processes on ergot alkaloids. The objective of this study was to determine the fate of ergot alkaloids present in sclerotia obtained from barley and wheat during malting. This type of data is essential for the determination of potential exposure and the assessment of risks associated with mycotoxins in brewing grains. Individual peptide alkaloids were determined by HPLC, and water-soluble alkaloids were determined by ELISA. Steeping appears to solubilize a small amount of peptide and water-soluble alkaloids, with kilning resulting in a more significant reduction (≈30%). The results of malting studies also suggest that cross contamination of barley with ergot alkaloids can occur. Beer was prepared from malt grist containing 0.1% (w/w) sclerotia. Mass balance calculations indicated that 32, 10, and 2 of the original total peptide alkaloids were recovered in the spent grain, wort, and beer, respectively. Average levels measured in beer were ≈10 ng/mL. A large amount of the original peptide alkaloids was lost during brewing and is believed to have resulted from thermal degradation. This was investigated further by treating aqueous extracts of sclerotia (pH 5.0) at 45, 70, and 100°C for 1 hr. Losses of up to 46% of the original peptide alkaloids were observed after 1 hr at 100°C.