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Wine Sulfur Dioxide

Early in the winemaking process winemakers add sulfur dioxide (SO2) to wine in order to inhibit bacteria and wild yeast growth, although this is typically considered only if malolactic fermentation isn’t intended. Later in the process after fermentation SO2 is added to wine as an antioxidant and for its anti-microbial properties. As an antioxidant SO2 helps preserve the color, flavor, and stability of the wine. As an antimicrobial SO2 interferes with the metabolic pathways of yeast and bacteria.

When SO2 is added to wine, a portion of it becomes immediately bound while a remaining portion is unbound SO2 . The portion that is unbound is also called free SO2 and it is responsible for protecting the wine. The bound and free SO2 together are referred to as total SO2.

Free SO2 exists in two forms. The first form, bisulfite (HSO3-), is the predominant form but is relatively ineffective. The second form, molecular SO2, is the minor form and is responsible for protecting the wine. The amount of molecular SO2 available in wine is dependent upon the amount of free SO2 present and the pH. Typically 0.8 ppm of molecular SO2 provides adequate protection against bacteria growth and oxidation.


Titration Systems

A variety of titrations systems are available including one that is programmed with only wine methods including free and total sulfur dioxide, total titratable acidity and yeast assimilable nitrogen. Titration systems are available with 1 or 2 analog input boards that allow multiple sensors to be used. These systems can also be configured to have one or two dosing pumps. Having multiple dosing pumps allow for the use multiple titrants.

For high throughput some of the titration systems can be connected to an auto sampler for automated analysis of multiple samples.



Mini Titrators

Hanna Instruments pioneered the innovation of mini titrators for customers that were performing the sulfur dioxide titration manually to be able to use an automated system at a fraction of the price.

The mini titrators offer the precision of dosing by a syringe with the ease of pre-measured reagents and pre-standardized titrants.





A variety of ORP electrodes are available that include application specific versions made specifically for grape juice and must. These versions feature a ground glass junction with a plastic sleeve. These features are part of Hanna CPS (clogging prevention system) technology to prevent clogging of the reference junction by solids found in grape juice and must.




Accessories include the spare parts for the mini-titrators. These include the replacement tubing with valve, syringe, beakers and stir bars.


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