Simply put maceration is the process of soaking crushed grapes, seeds, and stems in a wine must to extract color and aroma compounds as well as tannins. This is where red wines get their color and tannins and it is the lack of maceration that makes white wines so light in color and nearly tannin free.
Maceration may take place either before or during fermentation. A cold soak takes place prior to yeast fermentation while an extended maceration takes place during primary fermentation at least but may be allowed to continue throughout the entire fermentation.
Provided by: Wine Makers Academy