YAN & nutrition

[Rice_Guy]

I have been running Yeast Nitrogen for a while and am frustrated that there isn't more about what is normal. As a start I contribute this:

Deetzil in 2013 had a thread which is a good intro to nitrogen calculations for yeast
https://www.winemakingtalk.com/threads/yeast-nutrients.39655/FermCalc.com is a web based program with lots of choices as yeast varieties -> ie nitrogen demand

Notes:
* a test is about 30 minutes, I have run only a few replicates,
* I do not have a reference lab to compare results with ,, therefore If you run it feedback is appreciated
* this data set was generated with the Vinmetrica reagents and a 0.01 accuracy pH meter
* the test involves three pH based titrations, one of the reagents is formalin (yup that smell when dissecting a pig in biology), it is an easy test to run
* the photo is a formaldehyde titration, the wife kicked me out, , , , as a second option this part is run in the bathroom with exhaust running
* YAN is a ppm quantity, ,, ie mg/liter

 

[Raptor99]

Thanks for sharing this! I don't make grape wine, at least not yet. I am surprised by the wide variation from one season to the next, with Italian white buckets ranging from 98 to 600 ppm average YAN. That is quite a range! I guess that the take away for those of us who are not equipped to measure YAN is that we should assume that the YAN is at the low end of the range and add nutrients accordingly.

 

[Rice_Guy]

. . I am surprised by the wide variation from one season to the next, with Italian white buckets ranging from 98 to 600 ppm average YAN. That is quite a range!

My take away was that supplier JM probably diluted the juice with a solution of urea. (I could organize the rest of the test numbers on buckets at some time).
(This was part of a science committee report to Prairie Home Vinters last week)

 

[MrFrench]

My take away was that supplier JM probably diluted the juice with a solution of urea.

Wait… what?

 

[RylanJacobs]

My take away was that supplier JM probably diluted the juice with a solution of urea. (I could organize the rest of the test numbers on buckets at some time).
(This was part of a science committee report to Prairie Home Vinters last week)

Rice_Guy, can you elaborate on the dilution with urea?


I know that "excess" yeast nutrient can lead to microbial issues. However, between the pH and ethanol, how much of a risk is it really? Seems to me it would be a greater (more real) risk to underestimate nutrients and end up with H2S and/or a stuck ferment.

 

[Rice_Guy]

Rice_Guy, can you elaborate on the dilution with urea?

Looking back at past club purchases the numbers for 2023 were unusual. ex red varietal SpGrav, Was 2023 a bad crop year in California? High moisture El Nino year? Other change in how ripe 15 varieties of grape would get?

Then why would the nitrogen read so high? Wouldn't it be more organic nitrogen with lower ppm readings? ,,,, So far the only really high nitrogen, local juice, I have seen was a vineyard with fertilizer in summer. ,,, And asking I find the purchasing person switched vendor.


note: the food industry buys ingredients based on specification

 

[RylanJacobs]

Looking back at past club purchases the numbers for 2023 were unusual. ex red varietal SpGrav, Was 2023 a bad crop year in California? High moisture El Nino year? Other change in how ripe 15 varieties of grape would get?

Then why would the nitrogen read so high? Wouldn't it be more organic nitrogen with lower ppm readings? ,,,, So far the only really high nitrogen, local juice, I have seen was a vineyard with fertilizer in summer. ,,, And asking I find the purchasing person switched vendor.
View attachment 108207

note: the food industry buys ingredients based on specification

So perhaps the YAN levels are correlated with the use of fertilizers in the vineyard? That makes sense.

Given the importance of YAN, I am surprised that this testing is not more common in the home winemaking world. To my knowledge, Vinmetrica is the only supplier of YAN testing for the home winemaker.

 

[Rice_Guy]

So perhaps the YAN levels are correlated with the use of fertilizers in the vineyard?

One of the samples looked at was a commercial winery/ club member who fertilized. his Marquette as a rose had 264ppm, with a nine day steep that grape was 276ppm. (Highest local sample to date) As a comparison my unfertilized Millot as a rose was 32ppm and with a nine day steep was 14ppm. I tested a @wood1954 finished 2021 Marquette wine at 24 ppm. M.D. in the club has 2023 unfertilized Marquette berries in the freezer and I am trying to get a control sample.

My unfertilized Petite Pearl as a rose was 110ppm. ,,, More numbers after the next club get together. ,,, It is an easy test to run.

 

[RylanJacobs]

One of the samples looked at was a commercial winery/ club member who fertilized. his Marquette as a rose had 264ppm, with a nine day steep that grape was 276ppm. (Highest local sample to date) As a comparison my unfertilized Millot as a rose was 32ppm and with a nine day steep was 14ppm. I tested a @wood1954 finished 2021 Marquette wine at 24 ppm. M.D. in the club has 2023 unfertilized Marquette berries in the freezer and I am trying to get a control sample.

My unfertilized Petite Pearl as a rose was 110ppm. ,,, More numbers after the next club get together. ,,, It is an easy test to run.

Do you think that YAN levels could vary based on press lots? Do you think a free run/light press would have lower YAN than a heavy press?

 

[Rice_Guy]

Do you think that YAN levels could vary based on press lots? Do you think a free run/light press would have lower YAN than a heavy press?

1) yes, currently I feel that more dirt/ urea from birds/ insects is better.
2) unknown, I have asked around for samples that might be worth testing.
3) the start of this project was to eliminate “fried chicken” flavor @weaverschmitz named in contest wines. AKA reductive flavor.

 

[Rice_Guy]

A FEW YAN NUMBERS FOR COUNTRY WINE MUST

Notes:
* the must columns are estimates, when appropriate calculated at two kg per four liter batch (approx four pounds per gallon)
* a test is about 30 minutes, I have run only a few replicates, other than the crabapple mead must they represent collected juices.
* I do not have a reference lab to compare results with ,, therefore If you run it feedback is appreciated
* this data set was generated with the Vinmetrica reagents and a 0.01 accuracy pH meter, Vinmetrica developed this test for grape juice, not country fruit. University folks have used formalin titration on other fruits.
* the test involves three pH based titrations, one of the reagents is formalin (yup that smell when dissecting a pig in biology), it is an easy test to run
* YAN is a ppm quantity, ,, ie mg/liter

 

[Raptor99]

Thanks for sharing this! Am I correct in understanding that the readings are taken on the must, with the % of fruit given in the MUST usage rate column, with the rest of the volume made up by water?