(passion fruit, citrus ...) which are naturally very soluble in the wort and are particularly suitable for some varieties such as Sauvignon and Colombard. In the "maceration of lees", the lees from the static settling are gathered in a refrigerated tank and agitated for several days. After filtration and fermentation they give a white wine also rich in thiols. The making of the wine The wort is then placed in a tank to undergo fermentation. These fermentation tanks can be of several types: oak, cement coated with epoxy, stainless or enamelled steel, or epoxy resin. For large volume tanks the control of temperature, which typically is around 18 °C, becomes necessary. The majority of aromatic components (acetates of alcohol and ethyl esters of fatty acids) are synthesized by the yeast during fermentation of light juice below 18 °C. However, clarity and low temperatures are factors which slow fermentation. Recourse to the addition of selected yeasts for these difficult working conditions becomes crucial. In contrast some producers grow their vines organically or biodynamically: the lees are of good quality without synthetic chemicals harmful to yeast so they are kept in the wine. Turbidity of the must ensures a good supply of yeasts and fermentation in small tanks or in barrels then does not require mastery of cold. Fermentation starts spontaneously under the action of the natural yeasts from the grapes. The winemaker can choose to use a commercially available active dry yeast. It can help to express the characteristics of a variety or a method of manufacture. For a dry white wine fermentation continues until the sugar runs out. The wine is then usually decanted to eliminate the lees. When fermentation is done in barrels the temperature often exceeds 20 °C or even 25 °C. After the end of fermentation, the wine may also have malolactic fermentation or FML. This second fermentation carried out by bacteria deacidifies the wine: it transforms the malic acid, which has two carboxyl groups, into lactic acid. This operation, which reduces the biting acidity of the wine, is not always desirable nor practiced. In southern areas the acidity is carefully preserved to give the wine its liveliness for refreshing Aroma of wine. During the fermentation of the grapes varietal aromas are reduced in favour of an increase in roundness and volume in the mouth of the wine during ageing in oak barrels. It gives a better