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.