Name (also glycerol or propanetriol) for a colourless, syrupy, trivalent type of alcohol. It is produced as a primary and valuable by-product mainly at the beginning of the alcoholic fermentation, mainly by wild yeasts which are typical of vineyards. This means that a spontaneous fermentation usually results in higher amounts of glycerine. In a controlled fermentation with artificial yeasts, the ratio of glycerol to ethanol (the most common type of alcohol in wine) is about 1 to 12. The higher the alcohol content, the higher the glycerol content. The name is derived from the Greek "glykos" (sweet), as the substance tastes slightly sweet. However, it only has a slight influence on the sweetness of a wine. A high proportion causes a positively evaluated viscosity (thick liquid) in the wine. This is why glycerine is also colloquially called "oil sweet".
Such a wine is described as fatty (rich in alcohol) and/or oily (full-bodied, velvety) or also extract sweet (oil-sweet). The proportion is between 6 and 10 g/l for healthy grapes, and even up to 25 g/l for noble sweet wines. Glycerine, however, has no influence on the phenomenon of church windows, the "tears" in a wine glass. By forbidden addition of synthetic glycerine, low extract wines can be "improved". However, such adulteration of wine must be proven by analytical methods. In the 19th century scheelisation (addition of glycerine) was still an official procedure. An increase in the glycerine content can be achieved by the Governo process, which is common in Chianti. See a list of all wine ingredients under total extract.