Must: The unfermented juice of grapes extracted by crushing or pressing; grape juice in the cask or vat before it is converted into wine.
Must Weight: Measurement of the sugar content in grape must, or unfermented grape juice, which indicates the potential alcohol of the juice were all of the sugar to be converted to alcohol during fermentation. Like Brix, Baumé and Oechsle, must weight is more accurately a measurement of the must's density or specific gravity.
Musty: Having an off-putting moldy or mildewy smell. The result of a wine being made from moldy grapes, stored in improperly cleaned tanks and barrels, or contaminated by a poor cork.
Oechsle: Scale used in Germany to measure sugar levels and other solids in grapes or must to determine ripeness and potential alcohol. This scale is based on the density or specific gravity of the must. See also Baumé and Brix.
Brix: A measurement of the sugar content of grapes, must and wine, indicating the degree of the grapes' ripeness (meaning sugar level) at harvest. Most table-wine grapes are harvested at between 21 and 25 Brix. To get an alcohol conversion level, multiply the stated Brix by .55.
Baumé: A measurement of the dissolved solids in grape juice that indicates the grapes’ sugar level and ripeness and therefore the potential alcohol in the wine. Commonly used by winemakers in France and Australia. Other sugar measurement scales include Oechsle and Brix.