Green Pepper - the 'Bellpepper' or Capsicum kind, is a characteristic note of Cabernet Sauvignon. It comes from the group of aromas called 'pyrazines' which pack a punch; only a small amount of this aroma compound is needed for us to detect it. In wine, they are most prominent in Cabernet Sauvignon grown in a cooler climates, as the pyrazines are lost when grapes develop lots of riper flavour in warm climates. Other grapes related to Cabernet Sauvignon also develop pyrazines - the green grape Sauvignon Blanc (asparagus, gooseberry, box leaf notes), the red grape Carmenere which can have very distinctive 'snow pea' notes, and Cabernet Franc which can smell leafy. If you smell Green Pepper in a red wine, along with high tannins, high acid, and a black fruit, blackcurrant (ribena, cassis) fruit character, it's a good sign you've got a Cabernet Sauvignon on your hands.