Determination of Yeast Assimilable Nitrogen (YAN) in Kombucha
The symbiotic culture of acetic and yeast bacteria immersed in the sweetened tea infusion triggers an alcoholic fermentation. This fermentation can be favoured by the presence of assimilable nitrogen (organic and inorganic) which can be added before fermentation starts. The quantity of assimilable nitrogen can also be controlled during the fermentation process itself in order to guarantee a complete evolution of the fermentation avoiding undesired organoleptic deviations in the finished product.
Method
Sample treatment
For precise and repeatable analysis, degas the sample using the ultrasonic bath (code 222062) and clarify it, if necessary, using the centrifuge (code 222061).
Principle of the test
Organic nitrogen (α – amino nitrogen) and inorganic nitrogen (ammonium ion) are determined separately. In the presence of ammonium and NADH the glutamate dehydrogenase (Gl-DH) reacts with α-keto glutarate to form L-glutamic acid and NAD+. The decrease in absorbance, measured at 366 nm (end-point), of the NADH solution is proportional to the quantity of Inorganic Nitrogen present in the sample expressed in mg/L.
The Organic Nitrogen (α-amino) reacts in the presence of N-acetyl-L-cysteine with the o-phthalaldehyde forming an isoindolic derivative. The difference in absorbance, measured at 366 nm (end-point) is correlated with the quantity of organic nitrogen expressed in mg/L.
Calibration curve
The calibration curve of the CDR KombuchaLab, carried out using the known concentration of isoleucine for the organic nitrogen and ammonium chloride for inorganic nitrogen, confirmed an excellent linearity of the system over the entire measurement range.
...
...
Reagent test Kits
Kit Organic Nitrogren:
Code*301430: 100 tests
Code*301435: 10 tests
Kit Inorganic Nitrogren:
Code*301440: 100 tests
Code*301445: 10 tests
Please note: Organic (*301430, *301435) and Inorganic Nitrogen (*301440, *301445) kits must be used together.
Measuring range
| Analyses | Measuring range | Resolution | Repeatability |
|---|---|---|---|
| Organic nitrogen | 30 - 300 mg/L | 1 mg/L | 15 mg/L |
| Inorganic nitrogen | 30 - 300 mg/L | 1 mg/L | 11 mg/L |
The Analyzers for process and quality control in kombucha brewing
CDR KombuchaLab
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 KombuchaLab Jr
Partial analysis panel, customisable configuration
Up to 3 determinations simultaneously
Wireless connection to external printer
USB connections