Aug 25 2023

2023 Vintage

Harvest Special: Wednesday is YAN Day

YAN stands for Yeast Assimilable Nitrogen. This is the main nutrient that the yeast need for a healthy fermentation. YAN has two parts: Ammonia and  FAN (free amino Nitrogen).

The Ammonia is usually utilized first and is considered to be  of lower quality for fermentation. The FAN, or amino acids, are the higher quality N component.

Low or insufficient YAN can cause stress for the yeast and has been implicated in production of the unpleasant odors of Hydrogen Sulfide (H2S), which is like rotten eggs. These odors can be nasty in themselves and also will mask the desirable aromas of our wines. Over time they will degrade further and totally ruin the wine.

Excess Nitrogen in the must may not be fully utilized during  fermentation. It will then be leftover in the wine,  possibly to feed microbes and cause problems later on.

Knowing the baseline YAN in harvested grapes is therefore essential for healthy fermentation.

Nutrient supplements can then be added to the fermenting must to correct to the best level.

I perform an enzymatic test on a fresh or frozen juice sample. The test is in two parts, one for the Ammonia and the second for FAN. The result will show the value for NH3 (corrected to amino units) and FAN in mg/Liter. The total of the two is your YAN.

This is useful and timely information that will help the winemaker make simple adjustments and prevent difficult problems later on.

The price for this test, and many others, is on my Lab Test prices sheet, 

However, for Georgia winemakers the price will be capped at $35 per sample . This is on the condition that I receive the samples prior to Wednesday at 10 am. They will be run that day and results emailed by noon Thursday!

Remember juice samples for YAN can be frozen when sampled. I will thaw them. This will not affect the results.

Cheers and Happy Harvest

Ariel Wine Consulting.   706-969-1733