Determination of tannins in wine and must

CDR WineLab analysis system fast, simple to use and reliable for determining multiple parameters in wine and must

Tannins are relatively large phenolic polymers that derive from the polymerisation reaction of phenolic monomers. Their reaction with glycoproteins present in saliva determines the sensory sensation of astringency. They are present in all the solid parts of the grape (skins, seeds and stalks), flow into the must during the maceration phase and end up in the wine.

The CDR WineLab® method aims to monitor the concentration of tannins in wine in order to monitor the evolution of these both during alcoholic fermentation and during the micro-oxygenation phase.

The reference method used for comparison (Ribérau-Gayon and Stonestreet 1966) is based on the hydrolysis of these compounds in an acidic environment (Bate-Smith reaction) which releases highly unstable carbocations which precipitate in the form of brown-coloured polymers. The reference method is very complex and requires the sample to remain in a bain-marie at 100°C during the reaction. The reaction time is 30 minutes.

Optimisation of the CDR method reduces reaction time to just 5 minutes using a  microwave

So the CDR WineLab method® optimises the reference method because it reduces the analysis time and is very simple to perform directly in the winery.

In addition, the CDR WineLab® method® optimises the reference method for repeatability: the standard deviation ranges from 0.13 g/L with the reference method to 0.07 g/L with the CDR method. 

The determination of tannins is part of a broad analysis panel developed by the CDR laboratories, implemented on CDR WineLab®®, which offers the oenologist a precise and accurate control of both the polyphenolic extraction phase in red wines (maceration), and the subsequent phase of polyphenolic stabilisation (and therefore of colour stabilisation) that occurs with the  micro-oxygenation process.

To learn more read ”Controlling Maceration and Micro-oxygenation in the wine-making process“.

The Analyzers CDR WineLab® for determining Tannins in Wine and Must

The system is supplied pre-calibrated and ready for use.
Results are expressed in accordance with the reference method.
It is also possible to standardize the system using samples with a known titration.
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 WineLab wine analyzerCDR WINELAB® CDR WineLab wine analyzer Junior VersionCDR WINELAB® JUNIOR
Analyses Wine and Must:

Acetic acid (volatile acidity)
Fermentable Sugars
Total Acidity
L-Lactic Acid
L-Malic Acid
Free sulfur dioxide
Total sulfur dioxide
Alcohol by Volume
Yeast Assimilable Nitrogen (YAN)
Gluconic Acid
Acetaldehyde (Ethanal)
pH
Total Polyphenols Index
Glycerol
Colour (tonality and intensity)
Total Polyphenols
Total Anthocyanins
Polymerised Anthocyanins
HCl Index
Tannins
Catechins
Copper
Configuration with tailored panel of analyses
Simultaneous Sample Analyses 16 3
Multiple Analyses on a Sample si

Method

Test type: End Point.
Time testing: 5 minutes.
Are possible test sessions with several samples, up to a maximum of 16.

Calibration curve

The correlation curve of the determination of tannins in wine and must with CDR WineLab®, carried out with respect to the reference method Ribérau-Gayon and Stonestreet 1966.

Correlation curve Tannins CDR WineLab reference method Ribérau-Gayon and Stonestreet 1966

 

Test Principle

The method developed by CDR for the determination of tannins is aimed exclusively at the category of condensed tannins. Normally, the concentration of condensed tannins ranges from approximately 1 to 4 g/L.

The CDR WineLab® method is based on the hydrolysis of tannins in an acidic environment (Bate-Smith reaction) which releases highly unstable carbocations which precipitate in the form of brown-coloured polymers when exposed to high temperatures. For this reason the CDR WineLab® method involves using a microwave to heat the tubes inside which the tannin hydrolysis reaction takes place.

The 520 nm precipitate reading performed with the CDR WineLab® instrument is directly proportional to the concentration of tannins in the sample, which the instrument returns at the end of the analysis in g/L.

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. *300xxx: 10 tests 

Code. *300xxx : 100 tests (10 packages of 10 tests)

The reagents have a shelf-life of 8 months.

Sample Processing

Wine: Use the wine as it is after centrifugation.
Must: Use the must as it is after centrifugation and degassing.

Measuring Range

Test Measuring range Resolution Repeatability
Tannins 0.3 – 5.5 g/L 0. g/L 0.1 g/L

Reagents developed by CDR S.r.l - Quality System Certified ISO 9001 Ed. 2015 - Certificate n. 9115

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Tannins was last modified: February 11th, 2019 by CDR s.r.l.