Grape juice

Grape juice meaning in winemaking

Grape juice is the liquid extracted from grapes through natural drainage or mechanical pressing, representing the foundation of all wine production. When grapes are crushed or pressed, they release their cellular contents including water, sugars, acids, and various flavor compounds. Free-run juice flows naturally from grapes under their own weight and is typically considered the highest quality, containing optimal sugar-to-acid ratios and fewer harsh tannins. Pressed juice is extracted through mechanical pressure and may contain higher levels of phenolic compounds and tannins from prolonged skin contact. In winemaking terminology, unfermented grape juice is specifically called must, which contains dissolved solids, pulp particles, and grape skins. The sugar content of grape juice, measured in degrees Brix, typically ranges from 20-25 degrees at harvest, directly correlating to the potential alcohol content of the finished wine. The pH level usually falls between 3.0-4.0, providing the necessary acidity for fermentation and wine stability. Different extraction methods and timing significantly influence the juice’s composition, color intensity, and ultimate wine character. Quality winemakers often separate free-run and pressed juices, using them for different wine styles or blending purposes to achieve desired flavor profiles and structural balance.