Grape must is the juice and crushed grapes that are used to make wine. It is typically made from fresh, ripe grapes that have been harvested from the vine and crushed to release their juice.

Grape must is an important component of the wine making process, as it provides the raw materials for the fermentation process that produces alcohol. The sugar in the grape must is converted into alcohol by the action of yeast, which is added to the must along with other ingredients, such as enzymes and nutrients.

The quality and character of the grape must can have a significant impact on the resulting wine, and winemakers often carefully select the grapes and adjust the must to achieve specific flavors and characteristics in the finished wine.

In addition to its use in wine making, grape must is also used in the production of other products, such as grape must syrup, which is a sweet, thick syrup made from concentrated grape must, and grape must jam, which is made by cooking down the must until it is thick and spreadable.