Coffee’s flavor potential is constantly changing, whether in green, roasted or liquid form. As a result, coffee must be considered a moving target. One’s impression of coffee at one point will not match one’s impression at another. it’s this fickleness that makes coffee one of the most challenging beverages to measure with accuracy or precision.
Since water represents the vast majority of the beverage, it is important to understand the interaction between water and specific flavor-producing substances found in the coffee bean. The flavor components that are ultimately extracted will depend upon the quality of the solvent (i.e., water), the solute (i.e., coffee) and the temperature and other conditions under which the brewing occurs.
The coffee liquor is comprised of liquids (including oils), gasses and partially dissolved solids. Some substances emerge from the liquid surface as aromas, while the more solid substances often sink to the bottom of the cup. This process can be observed when a paper filter has not been used, because a light layer of oil appears on the liquid’s surface, along with an accumulation of solids that are apparent once the cup is finished.
The flavoring-producing compounds found in brewed coffee have their own individual properties that may evolve once in a solution. These compounds must be viewed as individual entities as well as how they work with, or against, other compounds present. These various compounds can accentuate, contrast or conceal one another’s flavors. Understanding this essential concept will explain why certain minerals in water affect the overall flavor profile of the brewed coffee.
The flavor of coffee is an extremely complex balance of several individual flavor qualities and sensations. Many of the flavor compounds that are appreciated in the beverage would be unacceptable in isolation, or in too great a concentration. In most sensory literature, taste qualities are classified according to how they are perceived by the human body. Olfactory sensations, perceived by the olfactory lobe at the top of the nasal cavity, are classified as aromas when they originate from a food and are meant to be consumed, and fragrances, or olfactory sensations from non-foods that will not be consumed. Gustatory sensations are perceived by the taste buds on the tongue and around the mouth. Physical mouth sensations, such as body, smoothness and temperature, are tactile senses arising from nerves that are sensitive to texture and pressure. The trigeminal nerves sense pungency and are responsible for the fact that we can experience hot peppers, cool mint and a tingling sensation in the nose when sniffing certain spices such as black pepper. Other chemicals may create sensations of astringency, the drying of the mouth and tightening of mouth tissues.
