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.
Late Harvest: On labels, indicates that a wine was made from grapes picked later than normal and at a higher sugar (Brix) level than normal. Usually associated with botrytized and dessert-style wines.
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.
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.
Polyphenolic Ripeness: Also known as physiological ripeness, is the concentration of polyphenols in grape skins, seeds and stems, in contrast to the traditional form of measuring ripeness based on sugar content (Brix, Baumé, Oechsle). It has become a trend among vintners to rely more on polyphenolic ripeness than on sugar levels in recent years, as polyphenols are the source of wine's color, flavor and mouthfeel. As grapes mature, particularly in warmer climates, sugar levels frequently rise faster than polyphenol concentrations. Leaving grapes on the vine longer to achieve polyphenolic ripeness has led to an increase in alcohol levels due to higher sugar contents, particularly in California.
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.