Coffee aroma is the fragrance of brewed grounded coffee when infused with hot water.
The coffee aroma is closely related to coffee flavor, responsible for all coffee flavor attributes other than the mouthfeel and sweet, salt, bitter, and sour taste attributes that are perceived by the tongue. Therefore, it might be said that coffee aroma is the most important attribute of top-graded coffees.
Coffee aroma is perceived by two different mechanisms. It can either be sensed nasally via smelling the coffee through the nose or retronasally. Retronasal perception occurs when the coffee is either present in the mouth or has been swallowed and aromatic volatile compounds drift upward into the nasal passage.
Instant coffee also contains the components responsible for stimulation of our taste buds. The difference, however, is that instant coffee lacks most of the aromatic volatile compounds causing a dramatic decrease in the overall coffee flavor. Typical coffee aromas include floral, winey, chocolaty, spicy, tobaccoy, earthy, and fruity. Coffee aroma is also experienced after drinking the coffee when vapors drift upward into the nasal passage. This “retronasal” aroma is responsible for much of a coffee’s aftertaste. A coffee’s aroma is strongest shortly after roasting and then declines rapidly. Coffee freshness, including aroma, can be maintained for months if placed in proper storage immediately after roasting.
Perception of Coffee Aroma
Coffee aroma is perceived by two different mechanisms. It can either be sensed nasally via smelling the coffee through the nose or retronasally. Retronasal perception occurs when the coffee is either present in the mouth, or has been swallowed and aromatic volatile compounds drift upward into the nasal passage.
The number of aromatic compounds found in coffee increases every year. Today the number is well over 800, and as our analytical methods become more precise, more will be uncovered. Yet the perception of coffee aroma depends both on the concentration of the compound and its odor threshold. With that said, understanding coffee aroma is not as difficult as understanding how over 800 coffee elements interact with the olfactory epithelium. It is probable that a relatively small group of compounds that share both a high concentration and a low odor threshold make up the fragrance we know as coffee aroma.