Alpha-Amino Nitrogen (PAN)

Alpha-Amino Nitrogen (PAN)Alpha Amino Nitrogen (PAN FAN) is a combination of 20 amino acids utilized by vines, yeast, and bacteria. While they are naturally occurring in grapes, nutrient cocktails are also commonly added early on to facilitate complete fermentations and to prevent eggy H2S formation. These products used for supplementation are powerful modern tools that should be used sparingly and in consideration of their limitations. Not all amino acids are equal, and not

Alpha-Amino Nitrogen (PAN/FAN) is a combination of 20 amino acids utilized by vines, yeast, and bacteria. While they are naturally occurring in grapes, nutrient cocktails are also commonly added early on to facilitate complete fermentations and to prevent eggy H2S formation. These products used for supplementation are powerful modern tools that should be used sparingly and in consideration of their limitations. 

Not all amino acids are equal, and not all nutrients are nitrogen. In addition to amino acids, yeasts also require minerals from the soil and micronutrients from the vine, both of which increase in uptake and availability when grown on healthy soils. Healthy soils are full of bacteria, fungi, insects, grazing animals, and other plants that contribute to the biodiversity of the vineyard. As organic matter increases in healthy soils it facilitates the transport of amino acids and minerals to the vine. Utilizing natural systems to regulate the balance in a vineyard is far more advanced technology than we could ever supplement through nutrient cocktails. This is because these nutrients can be important precursors for flavor and phenolic metabolism that can’t be compensated for later. The soil and vine supply water, sugar, amino acids, minerals, and micronutrients, but the berry is solely responsible for synthesizing all secondary metabolites, including phenolics and flavors (Kennedy, 2002).

As far as nitrogen goes, amino acids are approximately 1.2x more effective than inorganic ammonium (DAP), but they have to be added early on in fermentation to be taken up by the yeasts. Alcohol strongly inhibits amino acid uptake transporters in yeast cell walls by as much as 90% at 3% ABV (Monteiro and Bisson, 1992). If added before, yeast can store excess nutrients in their vacuole for later use. Winemakers also need to consider the timing of their additions when targeting which microorganisms to supplement. If added before a cold soak, for instance, many of those nutrients can be taken up by non-fermentative bacteria and yeasts, therefore limiting the efficiency of the addition. 

The other benefit of limiting nutrient levels is aromatic complexity. Amino acids with simple structures like valine and alanine are utilized more readily by yeasts while complex structures like phenylalanine require more effort. Broadly speaking, simpler structures make faster fermentations and simpler flavors, whereas complex structures make slower fermentations and more complex flavors. Allowing the yeasts to metabolize all available nutrients is a moderate form of stress that can be beneficial to quality.

So, if you do choose to add nutrients, do so at the right time. Nitrogen supplementation is a convenient tool that can easily become a crutch for poor vineyard practices. Our ever-evolving understanding of vine and wine nutrition necessitates a more holistic understanding combining nitrogen, vitamins, minerals, and oxidation derived from balanced grape and wine production. 

To learn more about alpha-amino nitrogen and its importance in winemaking, become a Bound advising client.

References:

Kennedy, James. “Understanding Grape Berry Development.” Practical Winery and Vineyard24 (July 30, 2002).