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

B-420.29.900 [2020-10] Total Oxygen In Beer - Bottles and Cans

Only through measuring the total oxygen can the threat presented by oxygen uptake in beer packaged in bottles and cans be assessed. The total oxygen consists of the sum of dissolved oxygen in the beer together with the oxygen contained in the headspace [1].

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 total oxygen content (dissolved and in the headspace) in filled containers

Scope of Application

In the packaging immediately after filling in the container will be some oxygen in the liquid phase (dissolved) and also oxygen in the headspace.

The determination must be made within two hours after packing. After more than two hours after packing, the content of oxygen in the bundle will have already decreased considerably.

Principle

The bottled or canned beer is brought to 20 °C and mechanically shaken, thereby achieving equilibrium between the oxygen dissolved in the beer and the oxygen present in the headspace (Henry’s and Dalton’s laws). By directly measuring either the oxygen in the beer or in the headspace, the total oxygen can be calculated through referencing a table of values, which includes the headspace volume as a percentage of the fill volume.