Determination of the HCl index in wine and must

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

The HCl index is an indicator of the tannin polymerisation state and provides an indication of how these develop over time.

The evolution during the micro-oxygenation of tannins involves an increase in their volume and this index tends to decrease during this phase while it decreases more significantly after fining or during ageing.

The CDR WineLab®method optimises the reference method (Ribéreau-Gayon and Stonestreet) both from the point of view of ease of use and repeatability The standard deviation, in fact, ranges from 4.6 of the reference method to 2.5 of the CDR WineLab® method.

The determination of the HCl index 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), of the subsequent polyphenolic stabilisation phase (and therefore of the 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 HCl index 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®
Analyses Wine and Must:
Alcohol by Volume
Acetic acid (volatile acidity)
Fermentable Sugars
Total Acidity
L-Lactic Acid
L-Malic Acid
Free sulfur dioxide
Total sulfur dioxide
Yeast Assimilable Nitrogen (YAN)
Galacturonic Acid
Gluconic Acid
Acetaldehyde (Ethanal)
Total Polyphenols Index
Colour (tonality and intensity)
Total Polyphenols (Folin Ciocalteu)
Anthocyanins Extraction on Grapes
Total Anthocyanins
Polymerised Anthocyanins
HCl Index
Simultaneous Sample Analyses 16
Multiple Analyses on a Sample si


Test type: End Point.
Time testing: 6 minutes.

the analysis involves a sample incubation time of 7 hours.
Are possible test sessions with several samples, up to a maximum of 16.

Calibration curve

The correlation curve of the determination of the HCl index in wine with CDR WineLab®, carried out with respect to the Ribéreau-Gayon and Stonestreet reference method.

Correlation curve of HCL index with CDR WineLab method - reference method


Test Principle

This index is based on the instability of procyanidins, catechin oligomers, in a highly acidic environment. In conditions of high acidity these molecules tend to polymerise, forming brown polymers. The most condensed molecules precipitate rapidly while the least condensed tannins remain in solution.

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. *301035: 10 tests 

Code. *301030 : 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
HCl Index 5 – 50 1 2.5

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

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With the CDR system, you can perform your tests in total autonomy

Neither skilled staff nor a dedicated external laboratory is needed to use our systems. CDR FoodLab® optimizes traditional testing methods, making them faster and easier, while guaranteeing accuracy standards in line with the reference methods.

Analytical kit

CDR FoodLab® Analysis Systems use disposable pre-vialed reagents specifically developed by the research laboratories of CDR. The use of pre-vialed reagents and the analytical procedures allow:

  • a sample preparation that is quick and easy, when needed at all;
  • making analytical procedures extremely fast and easy;
  • removing all needs for complex calibration procedures.

Reagents come in aluminum packages containing 10 test tubes each to perform 10 tests (or packages for 100 tests containing 10 single packages of 10 test tubes each).

Just a few steps and results are yielded right away

Just a few steps will suffice to carry out your analysis in a rapid way in total autonomy. The system is composed of both the analyzer based on photometric technology and a kit of low toxicity, pre-vialed reagents, developed by CDR.

CDR FoodLab® is cost-effective because it does not require the use of expensive equipment and does not entail maintenance, assistance or calibration costs.
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