The variability associated with YAN provides a challenge to winemakers: the lack of predictability associated with hydrogen sulfide formation during primary fermentation due to unfulfilled nitrogen needs by wine yeasts.

One of the main arguments for avoiding “sulfur” as a description term for an aroma is due to the fact that there are actually several forms of aromatic sulfur-containing compounds found in wine, and they can have very different aromas (smells, odors) associated with that one compound.

Yeast nutrients are added to fermentation primarily to ensure the completion of fermentation and to limit the formation of sulphur-like off odours. It is a fairly common practice seeing that grape juice often contain insufficient nitrogen. This article covers some of the basic concepts of yeast nutrient management in winemaking.