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Sulfur Dioxide in Beer

Sulfur dioxide or sulfite is contained in almost all types of beer. Learn how to quantitatively determine sulfur dioxide in beer swiftly, efficiently, and reliably.

Picture with saying about measuring sulfur dioxide in beer Sulfur Dioxide in Beer
TestkitsSpectroquant® Sulfite Test

Photometric Determination of Sulfites with Ellman’s reagent

This Application Note demonstrates how the Spectroquant® Sulfite Test can be used to quantitatively determine sulfur dioxide in beer swiftly, efficiently, and reliably. Sulfur dioxide or sulfite is contained in almost all types of beer. On the one hand, it occurs in beer as a natural result of yeast fermentation. On the other hand, it is also an agent used as an additive to preserve the beer and its raw ingredients, e.g. hops.

Due to its characteristic property as a radical scavenger, the presence of SO2 prevents oxidative processes and also triggers the binding of carbonyl compounds, agents that cause a stale flavor in beer. Some people, however, react sensitively to SO2, showing symptoms such as nausea, vomiting, or headache. For this reason, some countries have defined limits that specify the maximum permissible concentration of SO2 in beer. In the EU, for example, according to Commission Regulation (EU) 2011/1129 the sulfur dioxide content may not exceed the limit of 20 mg/l SO2.2 Concentrations exceeding 10 mg/l SO2 must be indicated by the label “Contains sulfites”. The same mandatory declaration also applies in the USA.

Measuring deviceSpectroquant® Spectrophotometers
There are various analytical methods available to check the compliance with these limits. The European Brewery Con­vention (EBC) advocates a distillation method for quanti­fication, which, however, involves a high investment of time, thus making swift analysis difficult.5 A further method for the measurement of sulfur dioxide in beer – one advocated by both the EBC and the American Society of Brewing Chemists (ASBC) – is the so-called p‑rosaniline method. The disadvantage of this method is that it uses toxic, in some cases carcinogenic substances, for instance p-rosaniline, formaldehyde, and mercury chloride.

 

The Spectroquant® Sulfite Test using the photometric DTNB method offers a swift and precise alternative to the methods named above, with the additional advantage that it does not use any carcinogenic chemicals.

 

Sulfite Test Method Method Measuring range

Sample material in neutral solution, sulfite ions react with 2,2’-dinitro-5,5’-dithiodibenzoic acid (Ellman’s reagent) to form an organic thiosulfate. This reaction results in the release of a thiol, which is then determined photometrically. 0.8 – 48.0 mg/L SO2 1.0 – 60.0 mg/L SO32- Pale, clear beers In the case of dark and cloudy beers it is advisable to check the suitability of the test kit beforehand. 

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