We all know the so-called yeast. pressed, for baking bread. If we were to look at a tiny crumb of this yeast through a magnifying glass (n. p. under the microscope), then we would have noticed, that the crumb is made up of thousands of tiny cells, not exceeding length 1/100 millimeters. Each cell separately, it is a plant that lives for itself. Other types of yeast will look similar under glass, thus brewer's yeast, spirit and wine. The latter are distinguished by special features from the mentioned yeast species, and the most important of them is the ability to impart a characteristic wine aroma and taste to beverages. Apart from the name of wine yeast, there are again a whole host of species (about 100), which come in two types, t. j. as racial, that is, noble wine yeast and wild yeast, that is, yeast. Both types of wine yeast are found on grapes, as well as our fruits, but wild yeast, as more resistant to environmental conditions, far outweigh the noble ones. And because wine, made with wild yeast often has many disadvantages, and suede gives way to wine made with noble yeast, Therefore, when making wine, we try to prevent the growth of wild yeast, while creating the best conditions for the development of noble yeast. The easiest way would be to kill all yeasts by pouring boiling water over the fruit, and even better by boiling them or their juice, and then, after cooling, the task of the thus sterilized racial juice with wine yeast. We will often meet with this method in detailed regulations, because using it, we achieve two goals at the same time : to sterilize the fruit and make it easier to extract the juice from the fruit.