Effect of the addition of ammonium and amino acids to musts of Airen variety on aromatic composition and sensory properties of the obtained wine

Musts from Airen grapes to which ammonium (100, 300 mg/l) and amino acids had been added (doubling the level of amino acids in that must) were fermented with three different yeast strains. Statistical treatments showed that the strain of yeast is the major factor affecting wine volatile composition, but must nitrogen supplementation also has an influence. The addition of any source of nitrogen to the must reduces the contents in the wine of β-phenylethanol (ca. 65% reduction), methionol (ca. 70%) and isoamyl alcohol (40-65%) and increases wine content of propanoic acid by 30-130%. Wines from musts supplemented with ammonium are richer in ethyl lactate and c-3-hexenol and wines supplemented with amino acids are richer in γ-butyrolactone and isobutanol. From the sensory point of view, must supplementation with ammonium brings about a decrease in sulphury notes and an increase in citric flavour. The effect of amino acid supplementation depends on the yeast strain. In one case, the effect is similar to that of ammonium supplementation; in the others an increase in fruity and fusel notes was obtained.