Name (also flor yeast) for special yeasts of the species Saccharomyces bayanus, capensis, cheriensis, fermentati, montuliensis and rouxii. These are able to convert sugar into alcohol in the first anaerobic phase (without oxygen) of fermentation. Afterwards, the flor yeasts can switch the metabolism to aerobic (with oxygen), so that a waxy, initially white coating is formed from alcohol and oxygen, which coats the individual yeast cells. This causes the yeast cells to rise to the surface of the wine and form a centimetre-thick layer (film) that increasingly turns brown. This protects the wine from air...