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The many facets of coffee aroma.

The many facets of coffee aroma

Aroma is such an important factor in establishing and maintaining a coffee franchise, that more attention should be paid to its components and how individuals detect, identify and react to their specific smells. There is no question that the aroma of fresh percolating coffee is one of the most delightful scents known to mankind: Compensating for a difficult awakening; adding enjoyment to a pleasant work break; supplying a gratifying top note at the end of a banquet. But this aroma is a complicated perfume made of many different notes. Why and how people react to various constituents of this odor might lead to the development of even more attractive bouquets.

Coffee aroma is a delicate composition, with several recognizable individual effects by average consumers; and many more detectable by a professional nose. More volatile oils come off first, followed by a heavier basic aroma. It is highly distinctive, with practically no other common aroma even coming close to imitating it. It has never been established whether it is an acquired affection or an innate taste; but few individuals are repelled by it, even if they have never previously encountered it.

Detection of this aroma occurs only in the nose, never in the mouth, even though most people feel they detect it on the palate. Many coffee flavor effects, other than aroma, are detected in the oral cavity--the mild bitterness, a slight astringency, a barely noticed salinity, a mild acidity; but the aroma notes, whether directly from the cup, or from the ingested brew, all must enter the nasal passages to achieve recognition.

Lower portions of the nose are insensitive to aromatic gases. Detection occurs high up in the nasal cavity. There, in about two square inches of surface, some 50 million olefactory nerve endings react to volatile stimuli. These endings consist of tiny delicate hairs which hang down from the roof of the nose, where they are constantly bathed in a film of liquid mucus.

When some of the coffee bouquet arrives with inspired air, various components dissolve in the mucus. Each stimulates a different nerve end. Individuals vary in their sensitivity to the quantity of aromatic reaching these nerves--some being appreciative of one part per million or less, while others may be totally blind to specific chemical vapors.

The nerve endings translate these odor stimuli to an electrical impulse which varies with the character of the aroma and its concentration. This electrical charge is transmitted as a signal via a nerve tunneling through the skull to a section of the brain containing olfectory bulbs. These are two match-head size organs located under the front of the brain, about eyebrow level. There, in the bulbs, it is believed that we first become aware that we smell something. But actually identifying the odor probably occurs in the olfactory cortex, deep inside the brain.

The cortex, it is theorized, puts a label on the particular aroma. The other brain centers combine the electrical signals with other senses and trigger memories and emotions associated with past exposure to that particular odor. Within an instant of exposure to coffee roasting, percolation or brew, the brain compares the aroma electrical charge with others in its memory bank and identifies it. An instant later the brain forms a mental picture of a hot cup of coffee and a feeling of awakening, pleasure or contentment permeates it. That's smelling!

Floral Note

When a can of roasted, ground coffee is opened and inhaled, a number of volatiles enter the nostrils. Foremost is a definite floral note. Absence of this bright impression is responsible for the lower value of many growths. It is not a single impression but is composed of a number of components recognizable by educated noses which are trained to differentiate between odors such as rose, lilac and other floral chemicals present in multi-blended perfumes.

A second important aromatic factor is an unpleasant mercapton note. Mercaptons are a large family of chemicals which are combinations of hydrocarbons and sulfur. One of its members is utilized in minute amounts in heating and cooking gas so that a gas leak becomes easily detectable before an explosion or asphyxiation occurs. Another is a major ingredient of the fluid a skunk ejects when angered or frightened. "Coffee-Captan," a close relative, has been isolated from coffee aroma. It is the combination of this repulsive note underlying a greater proportion of floral attractiveness that is partially responsible for coffee aroma appeal.

Another important integral adjunct of coffee aroma is the empyreumatic or burnt tone resulting from roasting. This varies in proportion from a minimum in a moderate roast to a strong heavy charge in espresso brands. Lack of it in popular West Coast light roasts was responsible for many accusations that "they taste like dishwater." While burnt aromas are usually distasteful, their combination with floral and mercaptan effects makes coffee distinctive.

Temperature Variation

An important characteristic of coffee aroma is its variation with temperature. Variation of this flavor intensity with temperature follows roughly one of the basic laws of thermodynamics: Rate of reaction doubles for every 10 [degrees] C rise on the thermometer. Since 10 [degrees] C is equal to 18 [degrees] F, we approximate coffee flavor increase as follows: Assuming the flavor level of a cup of iced coffee at 32 [degrees] F is one, at 50 [degrees] F it would go up to two. At 70 [degrees] F it would double to four. At 90 [degrees] F it would grow to eight and 110 [degrees] F, a good drinking temperature, it would come up to 16; while at 130 [degrees] F, the maximum before burning the mouth, it would afford 32 times the flavor afforded by the cold coffee.

To recap, there are a number of aromatics present in coffee in addition to the basic three described. These are all detected individually by different nerve endings in the nose. These are instantly converted to electrical impulses which are severally transmitted to the olfactory bulbs. Here they are integrated and projected to the olfactory cortex for identification.

Coffee aroma is one of the few major commoditities that have remained relatively unchanged for well over three centuries. Blends with other common flavors such as cinnamon, peppermint, etc. have been marketed but have exhibited relatively little success. A more fundamental study of how we smell the various natural constituents, their cerebral activity and their contribution to acceptance or rejection of the beverage is indicated.
COPYRIGHT 1990 Lockwood Trade Journal Co., Inc.
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Copyright 1990 Gale, Cengage Learning. All rights reserved.

Article Details
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Author:Lee, Samuel
Publication:Tea & Coffee Trade Journal
Article Type:column
Date:May 1, 1990
Previous Article:On the market.
Next Article:The case for generic advertising in Britain.

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