3.4. Nitrogen compounds
The nitrogen content is important because it can be a growthlimiting
factor for S. cerevisiae (Ingledew & Kunkee, 1985) and it is the primary origin of premature fermentation arrests (Bisson,
1999). The composition of the nitrogen source in grape must depends
on a number of factors including the particular grape variety,
harvesting time, use of fertilizers and clearing method used.
Ammonium ion and amino acids are the main sources of nitrogen
for yeasts during the fermentation of grape must. Nitrogen metabolism
by yeasts produces compounds with a strong influence on
wine quality and sensory properties (Moreno-Arribas & Polo,
2009).