Yeast assimilable nitrogen

Yeast Assimilable Nitrogen or YAN is the combination of Free Amino Nitrogen (FAN), ammonia (NH3) and ammonium (NH4+) that is available for the yeast to use during fermentation. It is a critical nutrient for yeast health and performance, and can affect the quality of the wine, beer, and other fermented products.

Overview

YAN is used by yeast during fermentation to synthesize amino acids, proteins, and other molecules necessary for growth and metabolism. The amount of YAN in the must or wort can significantly influence the fermentation kinetics and the formation of fermentation aromas.

Importance in Fermentation

During fermentation, yeast cells rapidly multiply and metabolize sugars, producing alcohol, carbon dioxide, and other compounds. Adequate YAN levels are essential for yeast to maintain a healthy fermentation. If YAN levels are too low, yeast may become stressed, leading to sluggish or stuck fermentations and the production of undesirable sulfur compounds. If YAN levels are too high, it can lead to an overproduction of biomass and excessive heat generation.

Measurement and Adjustment

YAN can be measured in the lab using various methods, including the NOPA (nitrogen by o-phthaldialdehyde) assay and the Formol titration method. If YAN levels are found to be too low in the must or wort, additional nitrogen can be added in the form of diammonium phosphate (DAP) or complex yeast nutrients.

See Also

• Fermentation (wine)
• Fermentation (beer)
• Yeast
• Nitrogen

‎

‎ Template:Brewing-stub