An article by Anne Ortiz-Julien, Ann Dumont, Edouard Lordat and Gordon Specht which appeared in the January edition of Practical Winery & Vineyard discusses the relationship between nitrogen and aroma development during fermentation.
Nitrogen is a key factor that has a significant impact on wine fermentation. It is the most important yeast nutrient, influencing both fermentation kinetics and wine quality. Nitrogen is present in grape must in different forms: inorganic (ammonium) and organic (amino acids, peptides and proteins). Nitrogen that can be used by yeast during alcoholic fermentation is called “assimilable nitrogen.” The needs for assimilable nitrogen are different according to the wine yeast used.
Yeast cells also contain nitrogen in the form of proteins, peptides—particularly tripeptides—andamino acids. YAN (yeast assimilable nitrogen) includes free α-amino acids (AA), ammonium
and some peptides. Inactivated yeast-based nutrients can also be used by wine yeast to efficiently carry out alcoholic fermentation.
A full copy of the article can be downloaded by clicking on the following link: PWV Jan 2016 Nitrogen Roles article.