NITROGEN AMMONIA and a-AMINIC NITROGEN KIT

Nitrogen sources are a fundamental factor for the multiplication and development of yeasts, protagonists of alcoholic fermentation, and protagocatechinetic bacteria of malolactic fermentation. These sources are present in the must but are often added, e.g. in warmer vintages, to obtain a level of APA (Readily Assimilable Nitrogen) of at least 200 mg/l. APA is identified in the amino acid fraction of the must (yeasts do not metabolise proline), which is metabolised and catabolised with varying intensity by the yeasts depending on the fermentation progress. In general, these microorganisms utilise the ammonia fraction in the first fermentation phases, while in the later phases they make greater use of the amino acid fraction. The latter is integrated into the must/wine in the form of mixed activators and/or yeast derivatives. In addition, the nitrogen content influences the organoleptic characteristics of wines as it modulates the production of higher alcohols (precursors of esters with fruity notes) and sulphur molecules that can give wines a reduced taste.