Fusarium Profiling and Barley Malt Gushing Propensity

This study aimed to characterize and identify Fusarium fungi associated with barley malt samples showing gushing activity in quality control. The study included six different barley samples from different geographic locations in Europe. Barleys were malted in specially designed, computer- controlled micromalting equipment. Fungal contamination was determined with various polymerase chain reaction (PCR)-based assays including real-time PCR with group and species-specific primers, fungal profiling with PCR with denaturing high-performance liquid chromatography, and PCR with denaturing gradient gel electrophoresis. Furthermore, samples were tested for the presence of hydrophobins. Alternaria, Cochliobolus, and Fusarium were the dominant fungal genera in the barley samples. Two malt samples induced vigorous gushing in beer and in mineral water. Relatively high F. culmorum levels were determined in these malt samples. F. graminearum, F. poae, and F. Tricinctum were also detected in gushing-active samples. The production of gushing inducers during malting by F. culmorum, F. graminearum, and F. Tricinctum was verified by artificial contamination of barley. All strains multiplied in malting conditions and produced hydrophobins. However, differences were observed between isolates of the same species from different origins. This study showed that F. culmorum, F. graminearum, and F. Tricinctum are associated with elevated gushing risk.