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P-57. Inhibition of oxidative aging compounds in beer using active packing material vs. SO2-addition

Presenter: Constanze Ruff, Technische Universität Berlin, Institute of Food Technology and Food Chemistry, Chair of Brewing Science, Berlin, Germany
Coauthors: Thomas Kunz, and Frank-Jürgen Methner, Technische Universität Berlin, Institute of Food Technology and Food Chemistry, Chair of Brewing Science, Berlin, Germany

The origin of beer off flavors caused by oxidation has been attributed to the formation of specific aging compounds. The formation mechanisms, as different they are, mostly involve reactive oxygen species (ROS), highlighting the importance of intercepting oxygen reactions in the beer matrices or avoid oxygen entry during the brewing process and storage. The aim of this study was to figure out the different influences of oxygen entry and oxygen entry inhibition using active packaging material in the crown cap compared to the antioxidative activity of SO2 addition on the formation of aging indicators during storage. In this correlation also the combined application of active packaging material and SO2 addition on oxidative stability was investigated. Could the well-tried SO2 addition obtain the best results or is it possible to offer brewers new knowledge to improve beer flavor stability? Previous investigations have shown that techniques combining EPR spectroscopy and ascertainment of specific aging compounds as oxygen indicators via GC-MS can be used to investigate the influences of SO2 addition and different crown liners with O2-scavenger properties on oxidative beer stability. The results after addition of oxygen to fresh beer samples verifies that the formation and increase in aging compounds is accelerated over storage time. In summary, the inhibition of oxidative processes by adequate SO2 addition in combination with after filling O2-scavenger material in the crown liner is the best way to increase oxidative beer stability during storage. However, the achievable increase in oxidative stability using different crown liner materials is strongly dependent on O2-scavenger properties. The compound with the lowest O2-scavenger properties showed an effect only after a longer storage time by the inhibition of oxygen diffusion through the crown cap and wasn’t able to compensate for the advantage effect of SO2 addition at 6 mg/L on oxidative stability. The best O2 scavenger acted directly after filling, as well as during storage, and was able to compensate for SO2 addition at higher than 6 mg/L. A remarkable and, for the mechanism, important point is that a comparable increase in oxidative stability with SO2 addition or O2 scavenger leads to a different positive effect on the formation of aging compounds during storage. In this connection with use of O2-active packing materials, a stronger reaction inhibition in the generation of specific aging compounds (oxygen indicators) was detectable. Altogether this research offers brewers useful further knowledge about how to proceed to increase oxidative beer stability through SO2 addition and/or active packaging material.

Constanze Ruff started her scientific career by participating in chemistry summer school at the Freie Universität Berlin before graduating. After school she interned for three months at Herbstreith & Fox Company in Neuenbürg, Germany. She then began studies in chemistry at the Freie Universität Berlin. In March 2011 she switched to TU Berlin to the Department of Food Chemistry to complete her course of diploma studies in food chemistry. At the moment she is working on her pre-diploma (Studienarbeit). She began her research work in November 2010 as a student research assistant at the Technische Universität Berlin, Institute of Food Technology and Food Chemistry, Chair of Brewing Science, where she works on GC/MS detection of aging compounds and improvement of oxidative beer flavor stability. 

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