C. GEIßINGER (1), K. Hofer (2), K. Habler (3), M. Gastl (1), T. Becker (1);
(1) Lehrstuhl für Brau- und Getränketechnologie (TUM), Freising, Germany; (2) Lehrstuhl für Phytopathologie (TUM), Freising, Germany; (3) Lehrstuhl für Analytische Lebensmittelchemie, Freising, Germany
Technical Session 6 - Yeast and Microbiology
Monday, June 15
2:00–3:45 p.m.
Flores 1–2
Fusarium infection in brewing cereals is a serious problem and a sign of poor malt quality. To evaluate the amount of Fusarium-damaged kernels, brewers and maltsters use visual assessment. Reddish discoloration is a common symptom of Fusarium-covered kernels caused by Fusarium species. In malt batches up to 5–7 red kernels per 200 g is acceptable for brewing use. Hitherto, little information has been available on the Fusarium species that cause these red kernels. In this study, over 50 barley malt samples were analyzed using RT-qPCR, (agar) plate cultures and visual assessment to determine which Fusarium species are responsible for the red discoloration of the barley kernels. In 2012 it was found that F. avenaceum was responsible for the red coloring of the seeds (R2 = 0.75). However, in 2013 F. tricinctum was the predominant species. In 2014, both, F. avenaceum and F. tricinctum were found to be liable for the symptoms. Correlation analyses were done with the collected data. Fusarium DNA was not only detected in colored malt; F. avenaceum and F. tricinctum DNA could also be found in many of these practice samples which seemed to be clean. To further substantiate these results, dilution series were carried out. In these dilution series, 0 to 40 kernels infected with F. avenaceum and F. tricinctum were added to a clean, greenhouse cultivated batch to a total weight of 200 g. RT-qPCR was done on these samples; a very good correlation between the amount of red kernels and corresponding Fusarium DNA was found. In this study it was possible to establish a correlation between the intensity of Fusarium infection and the proteolytic properties of malt. In the 2012 samples, there was a significant correlation between the amount of red kernels and the Kolbach index. In 2014, however, there was a very significant correlation between red kernels and the soluble nitrogen content. From the data collected in this study, it can be established that visual assessment can indicate increased Fusarium contamination.
After completing an apprenticeship as a brewer and maltster at the Andechs monastery brewery (Andechs, Germany), Cajetan Geißinger studied brewing and beverage technology at the Technische Universität München (TUM), Germany. He carried out his diploma thesis at the Institute of Brewing and Beverage Technology (Prof. Thomas Becker) at TUM-Weihenstephan, where the topic of his work was “Critical Examination and Systematic Assessment of the Modified Carlsberg Test (MCT).” In 2012 he began as a Ph.D. fellow under the supervision of Prof. Becker. A significant portion of his research activities are directed toward the investigation of the influence of fungal contamination on quality characteristics in cereal processing.
