Determination of Yeast Assimilable Nitrogen (YAN) in Must
Yeast assimilable nitrogen (YAN) is a test to manage correctly the alcoholic fermentation. The nitrogen deficiency can in fact cause a slowdown or even stoppage of the fermentation, which seriously affects the quality and organoleptic characteristics of wine. YAN is the sum of two contributes, the inorganic nitrogen present in the wine as ammonium ion and the organic nitrogen present in the α-amino form (amino acids). YAN analysis, with CDR method, allows to check the concentration of the two components separately giving the possibility to carry out with high accuracy, the necessary corrections before and during alcoholic fermentation.
The kit for the organic nitrogen component is selective for the α-amine to the exclusion of proline. In fact, this amino acid, present in high doses in the must, does not contribute to the improvement of fermentation because is not metabolized by yeast. The CDR method for YAN is more accurate than number of formalin, which partially intercepts the proline.
The inorganic nitrogen test is selective for the ammonium and it gives the possibility to adjust the amount of ammonium sulfate / hydrogen phosphate ammonium to add in the must.
Benefits of the CDR WineLab® method for the determination of YAN
The CDR WineLab® analytical method for the analysis in must:
- it is much easier than the method of the formol number generally used and it can be done in autonomous way in winery in real time without using toxic substances and with a simple photometric reading.
- it allows the determination of the two nitrogen parameters separately, giving the possibility of making any corrections in a way more accurate than the analysis with formol number;
- The result is not influenced by the presence of proline and hydroxy-proline, amino acids present in must, and not assimilated by yeasts.
Method
Test Principle
Organic Nitrogen
The α-amino nitrogen reacts, in presence of N-acetyl-L-cysteine, with the o-phthalaldehyde to form a isoindolic derivative. The difference in absorbance, measured at 366 nm (end-point) is correlated with the amount of organic nitrogen expressed as mg/L of N.
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Inorganic Nitrogen
The ammonium reacts by enzimatic path-way with NADH and α-ketoglutarate to give NAD+ and glutamate. The decrease in absorbance of the solution of NADH, measured at 366 nm (end-point), is proportional to the amount of ammonium nitrogen in the sample.
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Calibration Curve
Organic Nitrogen
The calibration curve of CDR WineLab® for the organic nitrogen analysis, obtained using reference methods, confirms the excellent linearity of the system over the whole testing range.
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Inorganic Nitrogen
The calibration curve of CDR WineLab® for the inorganic nitrogen analysis, obtained using reference methods, confirms the excellent linearity of the system over the whole testing range.
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Reagent test Kits
Measuring range
| Analyses | Measuring range | Resolution | Repeatability |
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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® Junior
- Partial analysis panel, supplied configured with 3 analyses of your choice, implementable
- Up to 3 determinations simultaneously
- Wireless connection to external printer
- USB connections