/ WORT, BEER AND BEER-BASED BEVERAGES / Beer / Oxygen and Air

B-420.31.100 [2020-10] "Air" and Oxygen in Headspace of Bottles and Cans – Underwater Funnel Method with Auxiliary Burette

The significance of oxygen over the course of the different stages of beer production varies:

If oxygen enters the process during mashing and wort handling, unsaturated fatty acids can become oxidized and phenolic compounds diminished, while the processes of starch degradation, lautering and extract yield are generally considered to be negatively affected [1]. However, the significance of the influence of oxygen at this stage of the process has been called into question [2, 3].

Oxygen is required for yeast reproduction immediately prior to the beginning of fermentation. However, excess oxygen can foster the formation of elevated concentrations of undesirable fermentation by-products. Downstream from primary fermentation, oxidation exerts an undesirable influence on the substances in beer, where the most harmful effects occur following filtration.

In the packaged beer, aside from the dissolved oxygen taken up during filtration and filling processes, the oxygen remaining in the headspace of bottles and cans is of consequence, as it can enter the beer through gas exchange.

Through the use of a properly designed filter with a well-devised system of bright tanks, wherein the tanks are thoroughly purged with CO₂ prior to filling, as well as suitable bottling and kegging lines, values for oxygen as low as 0.1 mg/l can be reached at the filter inlet and below 0.3 mg/l in the finished beer [4–7].

Literatur

L. Narziß, BWelt 127, 207, 1987
F. Schur, BR 97,117, 1986
H. Hug, P. Anderegg, H. Mändli und H. Pfenninger BR 97, 113, 1986
F. Ullmann BR 92, 143, 1981
H. G. Bellmer, BWelt 122, 1150 und 1166, 1982
L. Narziß, BWelt 122, 2293, 1982
P. Hoeren, MB 30, 36, 1977

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Application/Purpose

Determination of the "air volume" (gas volume other than carbon dioxide) and oxygen in the headspace of cylinders and cans

Scope of Application

Suitable for determination in beer, mixed beer beverages and carbonated beverages

Principle

The burette containing the caustic solution, in this case, is equipped with a short capillary outlet. A tube is attached to this outlet, connecting the burette to a second burette with a lower capillary outlet. The second burette contains an alkaline solution of sodium dithionite, which binds oxygen [1, 2]. In the first burette, the volume of air is measured, and in the second, the volume of nitrogen.