Coffee gets most of its flavor from the great variety of chemical compounds released when the ground particles make contact with water. Under normal circumstances, the water extracts about 80% of the available water soluble, flavoring compounds, which constitute the beverage's aroma, taste, body, and color. Together, these compounds create the sensory aspects of coffee's flavor.

Coffee beverage flavors differ, not only because of differences in blend and roast but also because the water removes each flavoring compound at a different rate. For example, water readily extracts the aromatic portion. Although small and hardly measurable in relation to the total extract, aromatic compounds significantly contribute to the perception of beverage flavor. The compounds responsible for taste (which dissolve in the water) and for body (which doesn't dissolve) are less easily removed. Both sets of aromatic and taste compounds contain many different chemical components, which combine to produce different beverage flavors.

During brewing, the total amount of flavoring material in the beverage changes, as does the proportion of each compound. In other words, the flavor changes continuously as time elapses. As a general rule, the most flavorful compounds are extracted first. The longer coffee particles remain in contact with the water, the greater the quantity of less flavorful compounds released. Prolonged extraction results in an unacceptable beverage flavor. The most desirable mixture of flavor elements occurs before you remove the maximum amount of material available. Consequently, for optimum results, you must stop the brewing process before the point of maximum extraction.

2. A coffee grind that matches the brewing time. Once you've established a coffee brewing formula, the method of brewing and the operation of the equipment come into play. To prevent under development or over extraction of the flavoring compounds, you must match the correct particle size (grind) of the coffee to the brewing method and type of equipment used. As a general rule, longer brewing times should be paired with larger (coarser) particles, and shorter brewing times should be paired with smaller (finer) particles.

3. Proper operation of brewing equipment: Brewing equipment normally controls three variables:

Time of contact between the coffee grounds and water. It takes time for the coffee particles to absorb the water, for the water to dissolve and extract the soluble material in the particles, and for the dissolved material to migrate into the beverage. Because water extracts different chemical compounds from ground coffee at different rates, the mixture of soluble materials in the beverage changes continuously. Therefore, controlling the brewing time contributes to optimal extraction and produces uniform results.

Temperature of the water. Cold water doesn't extract coffee acids as completely or as rapidly as hot water. Water that ranges in temperature from 195F to 205F liberates the aromatic materials more rapidly and permits proper extraction of other solubles within a reasonable time. As a general rule, the temperature should remain constant throughout the brewing cycle.

Turbulence. As water passes through and over the coffee grounds, it creates a mixing action known as turbulence. Sufficient turbulence is necessary to first wet the coffee particles and then to cause the water to flow uniformly through them. Wetting allows the water to penetrate the particle fibers, and a uniform flow allows the soluble material to dissolve. In addition, adequate turbulence prevents the water that is in immediate contact with the coffee from becoming so saturated with dissolved material that it can no longer remove additional flavoring compounds.

4. Optimum brewing method. Using the same type of coffee in different brewing equipment will create coffee beverages with different taste and body characteristics. The equipment's design will use one of six(6) basic methods to extract the flavoring materials from the ground coffee:

Decoction: Loose coffee grounds are mixed in a container with water that continues to boil for an arbitrary length of time. complete extraction usually occurs during this preparation method, due to the elevated water temperature of 212F and the extreme turbulence created by the boiling water. (Turkish Method)

Steeping:In this brewing method, coffee grounds in a container are mixed with hot water, lift in contact with the water for a specified length of time, and then separated from the extract or brew. The time of contact depends on the particle size, the water temperature, how much the grounds are agitated, and how quickly the grounds are separated from the beverage.

Percolation. The ground coffee is placed in a container that serves both as a brewing chamber and as a means of separating the grounds from the beverage. A pump moves the hot water to and through the coffee again and again. First the water, then the beverage extract, recirculates through the grounds, in this case, the time of contact depends upon grind size, the temperature of the water or extract, and the rate of recirculation. (Common Percolator Method)

Drip Filtration.: As with percolation, the grounds are placed in a container that serves both as a brewing chamber and as a means of separating the grounds from the beverage. In this method, however, the hot water flows through the coffee only once. The extract drips from the brewing chamber into a pot or other beverage receiver. The time of contact depends principally upon the rate that the water flows into the brewing chamber and the size of the grind. Other important factors include the water temperature, the chamber's shape, and the type of filter.(Common U.S. Drip Method)

Vacuum filtration: This method, which uses a two chamber device, is a variation on the steeping method. Steam pressure forces hot water from the lower chamber up through a filtering unit into the upper chamber, which contains coffee. Escaping vapor and stirring serve to agitate the coffee and water. When heat is removed after an arbitrary length of time, steam condenses in the lower chamber and creates a vacuum. The vacuum pulls the beverage down through the filter and into the lower chamber but leaves the grounds behind. The time of contact depends on how quickly a vacuum forms, the properties of the filter unit, and the particle size of the ground coffee. (Vacuum Press)

Pressurized infusion: Pressurized water between 2 and 10 atmospheres of pressure forced through the coffee grounds, which are compacted into a small cake in the brewing chamber. The combination of heat and the force of the water extracts soluble flavoring materials,.emulsifies insoluble oils, and suspends both ultra fine bean fiber particles and gas bubbles. This creates a beverage with an extremely high solubles concentration. To produce a uniform beverage with this method, rapid brewing times and extremely fine particle sizes are essential,. The brewing temperatures, 190-195F is slightly lower than for other methods. (Espresso)

5. Good Quality Water. When preparing a coffee beverage, water is just as important as the coffee. In fact, water represents more than 98% of the beverage. Water that contains some minerals favors the development of optimum beverage tastes. As a rule, water containing 50 to 100 parts per million of dissolved minerals will produce the best tasting beverage. The water should taste like fresh, good quality drinking water, have no odor, and contain no visible impurities.

6. An appropriate filtering medium. unless something separates the extract from the coffee grounds, the resulting beverage will be murky and difficult to drink. Filters, to varying degrees, clarify the beverage by separating the insoluble material from the brew. As a result, the filtering method directly affects the body of the beverage, and indirectly affects the flavor of the beverage.

1. A narrow range exists for extraction of the most flavorful soluble material. Solubles yields below 19% tend to have grassy and peanut-like tastes and are classified as 'under developed' tastes. Solubles yields above 22% tend to have unpleasant astringent and bitter tastes and are classified as 'over extracted' tastes. Extraction levels between 18% and 22% exhibit the most desirable flavors.
2. Concentration levels of soluble flavoring material have a broader range. Solubles concentrations below 1.15% coffee are considered 'weak'. They tend not to present the flavor of the coffee at an intensity where all of the components are above the taste threshold of the average person. Concentration levels above 1.35% coffee are considered 'strong'. They tend to present the flavor components at too intense a concentration to be easily perceived. for the average person, solubles concentrations between 1.15% and 1.35% tend to offer the most enjoyable level of intensity.
3. To reach the optimum flavor, solubles concentration needs to be in balance with solubles yield; the most flavorful mixture of soluble flavoring and material is presented at the most pleasing level of concentration. To reach this optimum balance between strength and extraction brewing formulas must fall within these specified ranges: