The fruit of the grape is a berry. Berries are attached to the stem. Many berries make
up the cluster or bunch of grapes. The essential parts of the berry include the skin, pulp,
and seeds.
The skin consists of an outer layer covering the berry. It is made up of six to ten
layers of thick walled cells. The outer surface of the skin is covered with a wax-like
coating called the cuticle, which renders the berry waterproof. The main components in
the skin are: coloring matter (red and yellow pigments), tannins, aromatic substances, and
potassium and other minerals.
Below the skin layer lies flesh or pulp which makes up most of the berry volume.
Cells in the pulp have large vacuoles containing the cell sap or juice. When the berry is
gently crushed, the fragile cells in the pulp are broken and the juice is released. This juice
is commonly referred to as the free run.
The seeds are localized in the center of the flesh. The berry contains two to
four seeds. They are rich in tannin which is extracted during fermentation (in red wines)