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Anthocyanins in must

Anthocyanins in must

Anthocyanins are chemical compounds present in the grape berry skin. They have a very low solubility in must and water but very much soluble in the alcohol that is produced by the alcoholic fermentation. Hence, wine colour is influenced by vine maturation and by the duration of the skin-juice maceration period.
Winemakers are deeply involved in enhancing red wine quality and for what concern vine and territory characteristics there is an increasing interest on studying of the phenolic compounds of grapes and wines. Mr Glories has developed a test method for phenolic maturation that permits to distinguish the phenolic potential of a specific vine, territory and year from the extractability characteristics of anthocyanins during the fermentation process.
The method is based on the use of two different pH values: the solution with pH equal to 1, extracts all the anthocyanins present, the one with pH 3,2 reproduces winemaking conditions. The difference between the two values gives an indication of the extractability of the pigments (Ea%) that is calculated through a mathematical expression. These parameters have a very high practical meaning since they can be used to monitor anthocyanins extraction process and adapt winemaking techniques to the real conditions in which the process undergoes.
CDR innovative method has simplified and speed up the extraction process and the testing time making possible to work directly "on the field": having test result in a few time, it is possible to make real time decisions.

Instruments to Use

WineLab is simple and reliable system to perform wine analysis.

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.

Reagents

Code *300459 – The kit, designed 10 antocyanes tests in must, contains:
- Bottle with A extraction solution, pH 1.0
- Bottle with B extraction solution, pH 3.2
- 20 cups with cap for extraction operations
(Syringe micro-filters for filtration may also be supplied on request)

Test method

Estimated extraction time: 1 hour ca.
Test type: End Point
Colorimetric reaction at 505 nm
Testing time: immediate
Calibration can be performed by aligning the test to reference values.

Test principle

Total Anthocyanins present in wine in a very acid environment (pH 1), develop a specific colour whose intensity, measured at 505 nm, is directly proportional to its concentration in the sample. It is expressed as mg/L
CDR innovative method simplifies and speeds up the reference test method.

Sample

Simplified must extraction method at pH 1 and pH 3.2. Modified Glories method.
Operating extraction technique

Grind the sample formed by full grapes in a mixer for 30 seconds at a medium-high speed.
Draw two samples, each of 6 g, and place them in the “disposable” cups provided for this purpose.
Add 6mL of solution A with pH 1 to the first sample.
Add 6mL of solution B with pH 3.2 to the second sample.
Cover the cups and wait 1 hour. Manually mix them a couple of times.
Filter or centrifuge the suspensions. 0.5 mL of filtered sample is sufficient for the test.