Definition - What does Juicing mean?
Juicing is the act of extracting liquid from vegetables or fruit. This can be done by pressing the fruit or vegetables or by creating an opening in order for the juice to run out. In winemaking, juice is the raw material needed to create wine which is expressed from the grape berries via a manual or mechanical tool that crushes or presses the grape clusters until the juice is expelled. Wine can also be made from the juice of other fruit.
WineFrog explains Juicing
The juicing of grapes following harvest can be done via two methods. For red grapes, the method for extracting juice is to "slice" or "crush" the grapes in order for the juice to run free from the fruit. This is called free-run.
In the case of white wine grapes, juice is carefully extracted from the fruit via a mechanized press. The grapes are then loaded into a large cylinder where an air bladder will inflate, slowly and gently expressing (pressing) the juices from the grapes.