Collective term (also fine) for processes to "beautify", "improve", "purify" or "preserve" a young wine. Degumming or clarifying, on the other hand, is usually understood to mean the processes for grape must. In the past, fining mainly meant the clarification of lees in a wine after fermentation, which was also called aerial fining. Today, the term encompasses many different technical cellar measures. By adding substances to the freshly fermented wine, unwanted suspended matter is bound by chemical reactions and/or adsorption. All these substances are electrically charged. Either negatively like yeasts and tannins or positively like proteins and gelatine. The fining agents must be oppositely charged in order to bind the lees particles to themselves. They are added in dissolved form and form insoluble flakes with the unwanted wine constituents, which sink to the bottom.
In ancient times, the Romans were already aware of the effect of whipped egg whites in winemaking. In the Middle Ages, there were some questionable procedures (or wine adulterations); for example, a "colour and taste improvement" with cattle blood. In the famous classic "Von Baw, Pfleg und Brauch des Weins" by the clergyman Johann Rasch (1540-1612), who worked in Wien, some techniques are described in detail. Among other things, he explains how to restore a cloudy wine, namely by adding freshly milked milk that is still warm from the cow. It was also known that certain substances such as isinglass, gelatine, Spanish earth (kaolin clay) and coal bind the suspended particles in the wine.
Fining ultimately achieves several effects. First of all, the natural settling of lees is accelerated considerably. Furthermore, substances bound in the wine are removed, which can lead to turbidity or negative effects after bottling. In addition, the removal of filtration-inhibiting substances facilitates any subsequent filtration. Finally, wine defects are at best prevented in the first place or eliminated after they occur. A distinction can be made between the three groups of physical-chemical substances such as proteins, tannins, crystals (tartar) and heavy metals, biological substances such as yeasts and bacteria and other substances such as dust, filter material and cork abrasion. Fining works best for wines with high acidity.
Optimal for many fining agents is a temperature...