During fermentation the grape skins and seeds float to the top of the fermenting bin, and how you manage that cap of skins has a big impact on the style of wine that comes from that fermentation. For a more extracted wine you need to keep the skins in contact with the fermenting juice more than if you are trying for a more elegant styled wine. In this Winemaker's Minute Crushpad CEO Michael Brill explains styles of cap management for small lot fermentation.
