Yeast Assimilable Nitrogen

Question 1

What is YAN

Answer 1

The part of nitrogen that can be used by yeast during alcoholic fermentation

Question 2

2 Different levels for YAN Importance

Answer 2

1. Important nutritional factor for yeasts during alc ferm due to its function as protein synthesis and sugar transport
2. It is important for the biosynthesis of wine quality markers like higher alcohols, thiols, and esters by wine yeast

Question 3

Nitrogen deficiency situations

Answer 3

Deficiency conditions = limited yeast growth and ferm speed. A low intial YAN concentration has been shown to cause slow and sluggish ferm. This is why nitrogen addition has become necessary in wine production.

Question 4

YAN Measurement

Answer 4

Good way to asses the general state of grapes in terms of nitrogen quantity, but not quality (key factor from ferm point of view and sensory quality of final wine)

Question 5

Organic or in-organic nitrogen

Answer 5

Organic has been shown to be most efficient and complete nutrient for securing ferm and developing full aromatic potential.

Question 6

In-organic nitrogen

Answer 6

Ammonium salts

Question 7

Organic Nitrogen (4)

Answer 7

Proteins, peptides, tripeptides, and free amino acids issued from yeasts

Question 8

Nitrogen impact on aroma (3)

Answer 8

• The metabolism of nitrogen, notably amino acids, generates the formation of numerous aroma compounds involved in the aroma matrix of wine: higher alcohols and their acetates.
• As a result, the nitrogen composition of the must can modulate the aroma profile of the wine.
• We need amino acids to get esters

Question 9

Esters

Answer 9

• The metabolism of amino acids (anabolism and catabolism) by yeast leads to the formation of higher alcohols, esters acetate and ethyl esters.

Question 10

Production of sulfites and sulfides during the fermentation is related to (5 things)

Answer 10

1. The amount of sulfates in must
2. The excessive clarification of must.
3. The lack of Nitrogen- containing nutrients (especially organic nutrients).
4. The excessive multiplication of cells, which leads to the depletion of nutrients.
5. Yeast genetics

Question 11

Role of Sulphur (3)

Answer 11

• Sulfur amino acids
  required for essential
  amino acids
• No varietal thiols for SB if we dont have sulfites
• Sulphur amino acid precursors–> alc ferm –> Varietal thiols