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 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).
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FAQs
Frequently Asked Questions
Supplies
- Centrifuge Tubes (SKU: G1005-50-2)
- Blank Label Sheets
- Label Template (Download)
- We supply 50 mL centrifuge tubes and labels for local Santa Barbara clients upon request.
Best Practices
- Collect a sample of your wine in a way that is most representative of the entire lot (i.e. practice flushing your sample valve, collecting after movements like pumpovers, stirring your barrel, etc.).
Label
- Label each sample appropriately with your Client ID, Sample Date, and Sample ID. Samples for Phenolics analysis also require a Crush Date, Varietal, and Appellation. The analysis cannot be performed without the applicable information for each sample.
- Mark the panel.
- Individual parameters can be added at the bottom of the label. A full list can be found on our ANALYSES page.
Clients are able to submit samples by contacting us directly and scheduling a pickup, delivering directly to our lab, or sending via the mail.
To arrange for pickup, clients must be located near Lompoc, Buellton, Santa Ynez, Goleta, or Santa Barbara and notify us by 11 am for same-day retrieval. Please contact us for more information.
- We provide same-day results by 7 pm with a guaranteed turnaround within 24 hours of sample receipt.
- Samples that are not analyzed same-daly are refrigerated overnight and analyzed first thing the next morning.
- Results are delivered via email in PDF format and uploaded to your account.
- Our invoices are sent via email and are due upon receipt.
- Your payment iOur invoices are sent via email and are due upon receipt.
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To ensure their stability, we ask our clients freeze their juice samples before shipment. Please contact Bound with any additional questions about sample preparation before shipment. We recommend expedited same-day to one-day shipping with a tracking number included.
Frozen
Samples can be placed in a freezer 24-hours in advance and shipped with an ice pack. Do not over-fill the polypropylene tubes or use glass containers as the frozen liquid will expand and could pose a safety concern. Freezing samples is a better alternative to boiling when analyzing compounds like ethanol, volatile acidity, free sulfur, and phenolics. Label each sample as "FROZEN".