Yeast needs nitrogen, among other things, to grow and ensure a smooth and complete alcoholic fermentation (AF). If the assimilable nitrogen is less than 140 mg/L, the grape must is considered deficient, and in this case wine yeasts need an addition of external nitrogen.
Nitrogen for the yeast comes in different forms
- Inorganic nitrogen or ammonium salts (ammonium sulphate or diammonium phosphate) provide nitrogen in mineral form. They are inexpensive and rich in assimilable nitrogen, but there is a risk of rapid fermentation at the start of the AF, with damaging peaks in temperature and sometimes even the production of undesirable aromas (sulphur compounds, volatile acidity).
- Organic nitrogen, which comes from yeast autolysates and provides nitrogen in the form of free amino acids and peptides. Organic nutrition based 100% on yeast autolysates ensures a smooth fermentation and has a positive influence on the sensory qualities of the wine through a natural supply of nitrogen in the form of easily assimilated, bio-available amino acids. It is also a source of minerals and vitamins to optimise growth and the fermentation and secondary (aromatic) metabolism of the yeast.
- Are there several types of organic nutrient? Some organic nutrients come from inactivated yeast, which is a product of living organisms and hence organic. However, inactivated yeast is less rich in amino acids and peptides than nutrients derived from yeast autolysates, and thus less effective. These differences are due to the processes used to obtain either inactivated yeast or yeast autolysates.
What is complex nutrition?
- A complex nutrient is a mixture of inactivated yeast and ammonium salts, with or without thiamine. It contains inorganic and organic fractions, with the proportions varying according to the application and the manufacturer. Depending on their formulation, they can be a good compromise for the secure fermentation of nitrogen-deficient (or highly nitrogen-deficient) musts.
Published Jan 26, 2024 | Updated Oct 1, 2024
NutritionOrganic nutrientsYeast nutrients