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Enhancing Flavour Stability in Beer Using Biological Scavengers (Part 1: Methodology and Preliminary Trials)
J. Kreim, L. Stumpf, S. Dobrick, J. Hinrichs, R. Pahl, J. Brauer and S. Schildbach

The diffusion of oxygen into the bottles and the subsequent oxidation of beer components is the main cause for deteriorating flavour during storage, limiting the shelf life of the beer. Active aerobic or facultative anaerobic microorganisms should be able to metabolise the oxygen before beer components are oxidized. In order to investigate this approach, two acetic acid bacteria (Acetobacter pasteurianus and Gluconobacter oxydans), as well as four yeasts (Rh bottom fermenting yeast, 68 obg. top-fermenting yeast, Saccharomycodes ludwigii and Brettanomyces bruxellensis), were tested. At first, these microorganisms were inoculated into a model beer. As the results were poor a second test series was conducted, in which the microorganisms were added into commercially available beer (German Pilsener). All microorganisms were capable of decreasing the initial oxygen concentration of approx. 2 ppm faster than the beer matrix itself, whereas the yeasts showed better results in a non-representative sensorial evaluation regarding prevention of oxidation smell and flavour than the bacteria. Especially long-term stability of the acetic acid bacteria seems to be an issue. Based on the results of the preliminary trials further investigation is required. Results will be presented in a second part following this paper.

Descriptors: biological scavengers, flavour stability, beer, bottle fermentation

BrewingScience, 71 (January/February 2018), pp. 12-17