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.
Method
Sample treatment
Wine is analyzed as it is. If necessary (sparkling or fermenting wine), the sample shall be degassed using the specific ultrasonic bath (code 222062). In case of tests performed on must, the sample shall be centrifuged (code 222061) or filtered (code 300210).
Principle of the test
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.
Calibration curve
The calibration curve of the CDR WineLab® instrument was made using standard solutions. The curve obtained confirmed an excellent linearity of the system on both measurement ranges.
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Reagent test Kits
Code*300583: 10 tests
Measuring range
| Analyses | Measuring range | Resolution | Repeatability |
|---|---|---|---|
| Gluconic Acid [0.1-3 g/L] | 0.1 - 3 g/L | 0.01 g/L | 0.04 g/L |
| Gluconic Acid [0.05-1.5 g/L] | 0.05 - 1.5 g/L | 0.01 g/L | 0.02 g/L |
Analyzers for process and quality control in winemaking
CDR WineLab®
Complete analysis panel, supplied already configured
Up to 16 determinations simultaneously
Possibility of carrying out analyses of the same sample
Integrated printer
Full connections (LAN - USB - Bluetooth barcode/QR code reader)
CDR WineLab® Jr
Partial analysis panel, customisable configuration
Up to 3 determinations simultaneously
Wireless connection to external printer
USB connections