C. HOLTZ (1), M. Gastl (1), T. Becker (1); (1) Lehrstuhl für Brau- und Getränketechnologie, Freising, Germany

Analytical
Friday, June 6 - 2:00 p.m.-3:45 p.m.
Level 4, Red Lacquer Ballroom

Lautering is known to be an important process step within the brewhouse. The insoluble parts of the mash are held back to gain high-quality wort. The most important wort quality attributes are high extract content and turbidity. The wort turbidity level influences further process steps as well as the final product. So far, fatty acids and starch are identified, among others, as the most important turbidity-causing substances. To investigate the extent of the influence of fatty acids and starch on turbidity levels, a synthetic wort medium was used. First the individual influence of both fatty acids and starch was investigated in distilled water and synthetic wort. Concentrations of single fatty acids (C14, C16, C18, C18:1, C18:2, C18:3) were added to distilled water and synthetic wort. The addition of single fatty acids to distilled water and synthetic wort showed similar results, with a linear correlation between fatty acid concentration and turbidity. Saturated fatty acids caused significantly higher turbidity levels than unsaturated fatty acids. Furthermore, increased concentrations of fatty acids caused both higher turbidity levels and an increase in relatively large particles based on agglomeration processes. For the investigation on the impact of starch on turbidity levels, gelatinized barley starch was added to distilled water and synthetic wort. Turbidity levels showed a linear correlation with the gelatinized barley starch concentrations. The addition of gelatinized barley starch to synthetic wort with fatty acid concentrations, equivalent to fatty acid concentrations in kettle full wort, showed cumulative effects on turbidity levels. To relate the results for the impact of fatty acids and starch on synthetic wort turbidity to findings in process wort with negative iodine tests, iodine tests were applied to find the achroic border for gelatinized barley starch in distilled water (1 mg/L) and synthetic wort (10 mg/L).

Christopher Holtz studied brewing and beverage technology at the Technische Universität München, Weihenstephan. Since 2010 he is a Ph.D. student at the Lehrstuhl für Brau- und Getränketechnologie, TU München-Weihenstephan. Christopher works in the field of NIR applications for analysis, evaluation, and prediction of lautering process performance parameters according to malt spectra.