Initiation of fermentation in the juice.
Who has good juice and wants to turn it into an equally good wine, will buy precious wine yeast before pressing, to set the so-called "mother yeast" before fermentation. To do this, you need a liter of self-pressed or store-bought fruit juice (the latter is most often pasteurized, and therefore free from any harmful microbes).
The juice is mixed in a large bottle with yeast. As already mentioned, different races are available, depending on the type of fruit, e.g.. such, which are best for apple wine or such, which are most suitable for currant wine.
Neighborhood residents, where grapevines are grown, can buy powdered yeast, they are dissolved in must, preparing "mother yeast". However, such yeast can only be purchased in large quantities, in quarter packs- and log frame shelves. Of course, only a few grams are needed for smaller amounts of wine (at normal fermentation temperature approx. 10 g na 100 l). The rest of the yeast should be packaged well and stored until the use-by date in the freezer compartment of the refrigerator (they have an expiry date of approximately one year, up to two years).
The three-quarters full bottle is covered with cotton wool and placed in a warm one (25°C) place. You need to shake the bottle from time to time, but yes, so as not to get the cotton wool wet. In this way, lying on the bottom and not yet activated yeast cells are lifted upwards and stimulated to fermentation.. Movement in the "mother yeast" is usually visible after a few hours, after one or two days at the latest. Foam forms, sok mętnieje, and when you smell cotton, there is a pungent smell. Carbon dioxide escapes, one of the products of yeast decomposed sugar (alcohol, Thank God, remains in the wine!).
After five days at the latest, yeast cells proliferated to this extent, that you can season all the juice with them. The addition of "mother yeast" acts as an injection; after another three days, turbulent fermentation begins in the actual fermentation vessel.
• For a quick start of turbulent fermentation, wine yeast should be multiplied in advance in a small amount of juice (1-2 l). The "yeast mother" fulfills the same role, what leavening the yeast dough.