Definition - What does Chocolate mean?
Chocolate is a wine descriptor sometimes used when smelling a rich wine that has a perfume similar to chocolate. This is a characteristic typically imparted by using certain toasted barrels to age wine.
Chocolate nuances which exist in wine are not the result of a winemaker adding chocolate in the winemaking process.
WineFrog explains Chocolate
The barrels which can impart a chocolate character will have a Medium Plus (M+), Heavy (H) or Toasted Heads (TH) toast. These are barrels that are used to age medium- to full-bodied wines which can handle the richer and heavier notes that will be imparted from the higher level of toasting.
A chocolate descriptor is what can be found in a wine's bouquet. On the palate, one may perceive it as mocha, cocoa powder or baking chocolate.