Designation of various substances that promote yeast propagation during fermentation. The yeasts need, among other things, potassium, sulphur, nitrogen and phosphorus for multiplication (sprouting). These nutrients are normally present in the grape must. A lack of nitrogen in particular can inhibit the formation of yeast cells or, in extreme cases, even lead to a fermentation standstill (stuck fermentation). For this reason, various nutrients are often added, which is mainly done with rotten or botrytised grapes or also in the production of fruit brandies. Such yeast nutrients are, for example, ammonium sulphate, diammonium phosphate and thiamine(vitamin B1). If necessary, these are sometimes added together. Within the EU, the maximum permissible amount of thiamine is 0.6 mg/l, of ammonium sulphate and/or diammonium phosphate 0.3 g/l. In the fermentation of nutrient-poor and highly clarified musts, the addition has a positive effect on the fermentation process and the aroma. Yeast rinds are also used as a supplement.
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