Determination of free sulfur dioxide in cider

Sulfur dioxide (SO2) is used in oenology mainly as preservative, but also for other purposes (for example for antiseptic, antioxidant, antioxidasic, solubilizing, combining and clarifying functions). Part of the SO2 that is added as potassium metabisulfite to cider undergoes a series of reactions. Therefore, after a short period of time, most of the sulfur dioxide reacts with some of the substances present, binds with them and forms addition compounds (combined sulfur dioxide) that are unable to express the typical properties of unbound molecules. Therefore, only the part that does not combine (free sulfur dioxide) plays an important role in preserving cider from oxidizing alterations and from some micro-organisms. This test can be used to determine the fraction of free SO².

The Analyzers CDR CiderLab for determining Free sulfur dioxide in Cider

The system is supplied pre-calibrated and ready for use.
Results are expressed in accordance with the reference method.
The reagents have a shelf-life untill 18 months
The analytical methods are simple: the system does not require an equipped laboratory or skilled staff.

	CDR CiderLab	CDR CiderLab JUNIOR
Analyses	Fermentable Sugars Total Acidity Acetic Acid L-Lactic Acid L-Malic Acid Alcohol Free sulfur dioxide (Free SO2) Total sulfur dioxide (Total SO2) pH Yeast assimilable nitrogen (YAN) Glycerol TPI – Total Polyphenols Index	Configuration with tailored panel of analyses
Simultaneous Sample Analyses	16	3
Multiple Analyses on a Sample		–

Method

Test type: kinetic.
Testing time: one test 3 minutes – 60 Tests/hour.
Are possible test sessions with several samples, up to a maximum of 16.

Calibration curve

The calibration curve of CDR CiderLab, obtained using reference methods.

Test Principle

SO₃^2- + RSSR <—–> RSSO₃– + RS-.
The free fraction of sulfur dioxide is made to react with an organic disulphide in order to form a colored compound, whose intensity, measured at 420 nm in kinetics, is directly proportional to the concentration of free sulfur dioxide in the sample.

Reagent test Kits

The reagents are packaged in foil pouches containing 10 tubes useful to perform 10 analyses.

This is the minimum package that allows the use of CDR systems even to those who need to make a few analyses, thus not wasting reagents.

There are also boxes of 100 tests, however, packaged in 10 bags of 10 tubes containing the reagent.

Code *300345 – The kit, designed for 10 tests

Code *300333 – The kit, designed for 100 tests

The reagents have a shelf-life of 18 months.

Processing – Sample Volume – Measuring Range direction

Use the cider as is.

Test	Measuring range (mg/L SO2)	Resolution	Repeatability
Free SO2	1 – 60	1	1,5 mg/L

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