Oechsle scale The mass difference between equivalent volumes of must and water is almost entirely due to the dissolved sugar in the must. Since the alcohol in wine is produced by fermentation of the sugar, the Oechsle scale is used to predict the maximal possible alcohol content of the finished wine. This measure is commonly used to select when to harvest grapes. In the vineyard, the must density is usually measured by using a refractometer by crushing a few grapes between the fingers and letting the must drip onto the glass prism of the refractometer. In countries using the Oechsle scale, the
Late harvest wine Late harvest wine Late harvest wine is wine made from grapes left on the vine longer than usual. "Late harvest" is usually an indication of a sweet dessert wine, such as late harvest Riesling. Late harvest grapes are often more similar to raisins, but have been naturally dehydrated while on the vine. Botrytis cinerea, or "noble rot", is a mold that causes grapes to lose nearly all of their water content. Wines made from botrytis-affected grapes are generally very sweet. Botrytis cinerea is a fungus that affects many wine grapes and causes them to shrivel into moldy raisins. The fungus