Organic acids in the form of nitrogen compounds. They are the basic building blocks for animal and vegetable proteins and elementary components of enzymes, glutamines and vitamins. There are about 100 different forms, about 20 of which are also contained in grape must. During the fermentation process, yeasts need certain amino acids to supply nitrogen during metabolism. They have to extract these from the must. If the soil is sufficiently supplied with nitrogen, the must also contains a sufficient amount of amino acids (about 1 g/l). The nitrogen content in the grapes is negatively influenced by botrytis (damage to the berry skin and leaching), water shortage, insufficient absorption of nitrogen via the roots and soil vegetation (competition for elementary nutrients).
A high degree of ripeness of the grapes has a positive effect on the nitrogen content. This is because amino acids are strongly formed especially towards the end of ripening, when the elementary nutrients are removed from the autumn leaves. Biogenic amines are formed from the amino acids by enzymatic decarboxylation. This is the most well-known histamine formed from histadine. Others are cadaverine, putrescine, spermidine, tryptamine and tyramine. Histamine is partly formed during alcoholic fermentation, malolactic fermentation and in higher concentrations during storage in wooden barrels. During autolysis (dissolution of yeast) the desired aromatic amino acids are formed. The wine contains 1 one to 4 g/l amino acids (see under total extract). The taste sensation umami is based on glutamic acid; one of the amino acids.