Physico-chemical separation process for fine-grained solids. Originally, it was mainly used in ore mining for the separation of ore from waste, non-ore bearing rock. In this process, the pale (more difficult to wet, lighter) rock or components are separated from the heavier ore containing rock. The deaf and lighter rocks rise to the surface and are skimmed off. Flotation agents are added to optimise the process. In the production of beer this has long been used to clarify the beverage from the wort (concentrate of water, malt and hops).
This flotation technique has now also been used for a relatively short time in winemaking for degumming, i.e. the removal of trub particles (grape skins and stalks etc.) from the grape must. Nitrogen or air is added to the must under pressure. When the pressure is released, tiny bubbles are formed to which the cloudy particles adhere and which float to the surface and can be removed. A distinction is made between continuous flotation (permanent skimming of the foam from the surface) and discontinuous flotation (respective draining of the clear must from below at short intervals of up to a maximum of two hours). Similar techniques used in viticulture are filtration and centrifugation.
Complete lists of the numerous vinification measures or cellar techniques, as well as the various types of wine, sparkling wine and distillate regulated by wine law are included under the keyword vinification. Comprehensive information on wine law can be found under the keyword wine law.