Determination of the Gluconic acid in must and wine
Musts and wines from grapes affected by grey mould may contain varying concentrations of gluconic acid depending on the severity of the attack. In fact the enzymatic action of mould on grapes results in the generation of gluconic acid due to the oxidation of glucose.
This situation leads to deterioration of the health status of the must and possible difficulties in triggering of alcoholic fermentation.
The Analyzers CDR WineLab® for determining gluconic acid 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® |  CDR WINELAB® JUNIOR | |
|---|---|---|
| Analyses | Fermentable Sugars Total Acidity Acetic Acid L-Lactic Acid L-Malic Acid Malolactic Fermentation Alcohol Free sulfur dioxide (Free SO2) Total sulfur dioxide (Total SO2) pH Yeast assimilable nitrogen (YAN) Gluconic Acid Glycerol Polyphenols TPI – Total Polyphenols Index Acetaldehyde (Ethanal) Anthocyanins Catechins Colour intensity and tonality Copper | Configuration with tailored panel of analyses |
| Simultaneous Sample Analyses | 16 | 3 |
| Multiple Analyses on a Sample |  | – |
Method
Test type: End Point.
Time testing: one test 6 minutes – 50 Test/Hour.
Analysis sessions with multiple samples up to a maximum of 16 are possible.
Correlation with the reference method
The correleation curve of CDR WineLab®, obtained using reference methods.
Test Principle
Gluconic acid is phosphorylated by the action of a suitable enzyme in the presence of ATP.
The adduct, formed through the action of NAD+, results in the formation of NADH in the ratio of 1:1 with gluconic acid present in the sample. The reaction, at end point, is measured at 366 nm and an increase in absorbance is directly proportional to the concentration of gluconic acid.
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. *300583 : 10 tests
Code. *300580 : 100 tests (10 packages of 10 tests)
The reagents have a shelf-life of 6 months.
Processing – Sample Volume – Measuring Range
MUST
For precise and repeatable analysis on the must, the sample must be degassed with the relevant ultrasonic bath and spun with the mini-centrifuge to separate the solid particles present in the solution.
WINE
Take the sample in its unaltered state (possibly degas with the relevant ultrasonic bath
| Test | Measuring range | Sample volume | Resolution | Repeatability |
|---|---|---|---|---|
| Gluconic acid | 0,05 – 3 g/L | 100 µL | 0,01 | 0,02 g/L |
