Simple method for detecting sulfite in wine and other beverages

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Traditionally, sulfur dioxide (SO2 or sulfite) has been thought of as a relatively innocuous preservative agent, acting mainly as a barrier against oxidation and undesirable bacteria. SO2, however, affects not only the stability but also the taste, bouquet and color of wine.

Prof. Levine’s group reported on a novel detection method for sulfur dioxide in aqueous solutions, in which the presence of sulfur dioxide leads to color changes of filter paper modified with both β-cyclodextrin and manganese. β-cyclodextrin was attached to the paper via coupling with succinic acid to get the sulfur dioxide sensor with outstanding practicality, as measured by the rapid color changes on paper visible by naked eye detection in the presence of sulfur dioxide concentrations that are relevant in the food and beverage industry.

This detection method is rapid (less than 5 min required for complete color change), sensitive (limits of detection as low as 33 ppm), broadly applicable (tolerant of a range of pH values), and practical (color changes can be observed via naked eye detection and quantified via straightforward color analysis). Extensive optimization of each component provides insight into the unique stabilizing effect of cyclodextrin in preventing the filter paper from permanganate-induced degradation, and mechanistic analysis points to an oxidation-reduction reaction as responsible for the observed color changes. Overall, these results lay the groundwork for the development of practical sulfur dioxide sensors for use in the food and beverage industry, and provide precedent for the use of cyclodextrin as a stabilizing force in paper-based chemical sensors.

Illustration of colorimetric changes of Whatman #1 filter paper functionalized with β-cyclodextrin and high oxidation manganese before exposure, and after exposure to solutions of 0 ppm SO2, 200 ppm SO2, and a commercial white wine sample. (Top: quantitative colorimetric values; Bottom: photographs of the papers under the investigated conditions).

Vincent Joseph, Oran Warhaftig, Shay Klein, Mindy Levine (2022) Paper-based manganese and β-cyclodextrin sensors for colorimetric sulfur dioxide detection. Analytica Chimica Acta, 1200, 339629,

Featured image: pixabay

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