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.

Determination of Yeast Assimilable Nitrogen (YAN) in Kombucha

CDR KombuchaLab the easy-to-use analysis system to optimise your kombucha production process by obtaining results in real time.

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CDR KombuchaLab

Test type: End Point.
Time testing: [uni].
Analysis sessions with multiple samples are possible for up to a maximum of 16 tests for CDR KombuchaLab and 3 tests for CDR KombuchaLab Junior.

Method

For precise and repeatable analysis, degas the sample using the ultrasonic bath (code 222062) and clarify it, if necessary, using the centrifuge (code 222061).

Sample treatment

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.

Principle of the test

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.

Calibration curve

Calibration curve of CDR KombuchaLab, performed using isoleucine standards with known organic nitrogen concentrations. R² = 0.9911

Calibration curve of the CDR KombuchaLab instrument, carried out using standards with a known concentration of ammonium chloride for inorganic nitrogen. R²=0.9945

Kit Organic Nitrogren:Code*301430: 100 tests Code*301435: 10 tests Kit Inorganic Nitrogren:Code*301440: 100 tests Code*301445: 10 tests<div class="font-bold">The reagents have a shelf-life of 9 months</div>Please note: Organic (*301430, *301435) and Inorganic Nitrogen (*301440, *301445) kits must be used together.

Reagent test Kits

<table class='table-auto'><tbody><tr style='border-bottom-width: 1px; border-color:#e4e9f2;'><th style='padding: .75rem 1.5rem .75rem 0; text-align: left;'>Analyses</th><th style='padding: .75rem 1.5rem .75rem 0; text-align: left;'>Measuring range</th><th style='padding: .75rem 1.5rem .75rem 0; text-align: left;'>Resolution</th><th style='padding: .75rem .75rem .75rem 0; text-align: left;'>Repeatability</th></tr><tr style='border-bottom-width: 1px; border-color:#e4e9f2;'><td style='padding: .75rem 1.5rem .75rem 0; text-align: left;'>Organic nitrogen</td><td style='padding: .75rem 1.5rem .75rem 0; text-align: left;'>30 - 300 mg/L</td><td style='padding: .75rem 1.5rem .75rem 0; text-align: left;'>1 mg/L</td><td style='padding: .75rem .75rem .75rem 0; text-align: left;'>15 mg/L</td></tr><tr><td style='padding: .75rem 1.5rem .75rem 0; text-align: left;'>Inorganic nitrogen</td><td style='padding: .75rem 1.5rem .75rem 0; text-align: left;'>30 - 300 mg/L</td><td style='padding: .75rem 1.5rem .75rem 0; text-align: left;'>1 mg/L</td><td style='padding: .75rem .75rem .75rem 0; text-align: left;'>11 mg/L</td></tr></tbody></table>

Measuring range

CDR KombuchaLab: the easy-to-use analysis system to optimise your kombucha production process by obtaining results in real time. Junior version