Pre-fermentation of the fruit pulp.
Some types of grapes and fruits are not pre-fermented as juice, but as a pulp, that is, in the form of crushed, but not the imprinted fruit.
This is what is done with the first dark grapes, because only by fermenting the pulp can their color be preserved in the later wine (only their skins contain the dye). Most berries also belong to this group. The wine obtained from them, especially high-percentage desserts, it should have a beautiful, intense color. This also applies to all fruits with a low juice content, which only after initial fermentation become more efficient. Belong to them: hawthorn, rowan, pigwa, tarnina. Finally, this group also includes fruits with a high pectin content, which gel easily and therefore harder to release juice (currants, agrest, plums). As a result of initial fermentation, the setting is degummed. Increasing the amount of juice can be obtained by adding an anti-gelling agent (I myself, however, never had to use it).
During the initial fermentation in the pulp, all parts of the fruit are fermented and leached, thanks to which the later wine will receive a stronger aroma and a more intense color.
Pulp fermentation must not take too long, nor should it be interrupted too quickly just because of that, that you have any doubts. These parts of the fruit, which are discarded during the pressing of the juice – skins, seeds, peduncles – contain large amounts of tannins, which cause, that the wine is more durable and clear, but they also make the wine taste sharper.
Pulp fermentation should then be stopped, when-according to our assessment – there has been enough juice to be squeezed out and when the color intensity is sufficient.
The pulp is set to ferment or in a balloon (from 15 liters) or in a barrel (a large infusion is required) or in another vessel with a wide neck and also with a closure. There are also special wooden fermentation containers, but – as far as I know – you can only buy them used and they are very hard to get. They are more practical – at least with large amounts – plastic containers with a capacity 100 liters with screw lid, which has a hole for the fermentation tube.
A large opening is important, because you have to stir the pulp thoroughly every day. During fermentation, a "cap" of foam forms on the surface of the liquid, pieces of fruit, earwig, stalks and pips, due to its large surface, it is an ideal breeding ground for acetic bacteria and wild yeast.
The wooden fermentation containers have a perforated lid, which traps the "cap" below the surface of the fluid.
• To get a wine with a cleaner "tone", you have to mix wine yeast or "mother yeast" with the pulp.
• The pulp vessel should also be fitted with a hydraulic seal filled with water.
• The sugar and acid content is not corrected in the pulp, but only in the must.
• Pulp not intended for wine, but for the distillate, it is neither sweetened nor crowded. It should ferment whole, then in that state, as it is, it is distilled.
• Careful winemakers add to the pulp made of very ripe or even overripe or not completely healthy fruit 10 g of potassium metabisulphide na 100 liters. This prevents wild fermentation and limits the action of other harmful microorganisms. The problem of sulphurization of the pulp, must and wine will be discussed in the next chapter.
• After a few days, the pre-fermented pulp is drawn into the appropriate fermentation vessel, and from the residue, i.e.. from the remnants of crushed fruit, the juice is squeezed out in a press.
• The weight of the pulp should be measured when setting it to ferment, for when the fermentation of the juice has already begun, sugar had already broken down into alcohol and carbon dioxide and Ochsle's weight would have to be recalculated backwards, which would take up too much space here.