As living organisms, yeasts and malolactic bacteria require specific nutrients in order to thrive. The correct choice of nutrients and timing of their application will guarantee optimum alcoholic and malolactic fermentation.
Microbiological processes, like alcoholic fermentation, are dynamic because they are adapted to the laws of nature and change according to environmental factors. The situation is further complicated by the fact that microorganisms have very complicated metabolisms. This combination forces the wine and sparkling wine industry to face new challenges again and again.
A successful and complete alcoholic fermentation requires wine yeasts to still be alive at the end of the fermentation process because they are the essential interface between grape must and wine. Nutrients available in adequate and sufficient form ensure their survival.
When it comes to yeast nutrients, grape must ingredients are still somewhat of a mystery. Routine measurements of the sugar concentration and pH value and analysis of organic acids are useless for the purpose of yeast development. There is no correlation between the sugar concentration of a must and the nitrogen concentration (amino acid concentration), nor are essential yeast nutrients such as minerals, vitamins, fatty acids, and sterols analyzed. Legislators are trying to compensate this poor knowledge through an approval procedure for yeast nutrient preparations.