Where Does Coffee's Rich Aroma Come From, and Why Does Specialty Coffee Smell More Aromatic Than It Tastes

When you brew coffee and cup it at FrontStreet Coffee, you often catch floral and fruity aromas drifting through the air, or notes of caramel, sugarcane and honey. Yet when you take a sip of the hot coffee, that wonderful sensation you smelled does not translate quite the same way. Put plainly, it does not taste as aromatic as it smelled.

To unravel the mystery, we need to understand coffee flavor and our sense of smell first. Some acidic and sweet flavors are both water-soluble and volatile, meaning they can be detected by smell and by taste alike.

Coffee Flavor

Coffee flavor is made up of volatile aromas (gases), water-soluble tastes and mouthfeel.

Volatile aromas include dry fragrance and wet aroma, perceived through both orthonasal and retronasal olfaction.

Water-soluble tastes cover sour, sweet, bitter, salty and umami, detected by the taste receptors in the mouth.

Mouthfeel, made up of smoothness and astringency, results from the interaction of sour, sweet, bitter, salty and umami in different proportions.

Why Coffee Smells More Aromatic Than It Tastes

The reason coffee smells more aromatic than it tastes comes down to the Maillard reaction during roasting, which combines volatile compounds such as esters and aldehydes with the coffee beans' organic acids.

Coffee uniquely contains an enormous range of complex chemical compounds. Besides those above, it also holds other organic acids, inorganic acids, alkaloids and more.

When the coffee is ground or brewed, these volatile compounds and organic acids vaporize, which is how we perceive the pleasant coffee aroma.

Of the more than 850 aromatic compounds in coffee, most are only volatile and can be identified solely through our sense of smell. A portion possess both volatile and water-soluble properties, so they can be perceived by smell and taste at once. The purely water-soluble aromatic compounds are the fewest and must be picked up by the taste buds.

Because most of coffee's aromatic compounds are volatile, many people find smelling coffee more satisfying than drinking it.

Orthonasal and Retronasal Olfaction

Generally, our sensory perception of flavor follows this hierarchy: smell, then taste, then mouthfeel.

Smell is broader and more accurate than taste and mouthfeel because it is the only sense with a dual function. The nose can detect odors from the outside world, known as orthonasal olfaction, but it can also "smell" the aromas of food and drink inside our mouths, known as retronasal olfaction.

Coffee's volatile components, including caramel, cream, acidity, floral, fruity, herbal, nutty, grainy, resinous, wine-like, spicy, smoky, earthy, woody and medicinal notes, are all perceived through both orthonasal and retronasal olfaction.

Some flavor molecules with sour and sweet characteristics are both volatile and water-soluble, so they can be enjoyed by smell and taste together. Unpleasant bitter and salty flavors, however, are water-soluble but not volatile, meaning they can only be detected by taste, which is why many people find coffee nicer to smell than to drink.

Research also suggests another reason coffee's taste shifts: of the 631 chemical compounds that make up coffee flavor, 300 are destroyed by saliva, so the flavor changes even before we swallow.

In his book "Coffee Science," Mr. Han Huaizong explained that coffee smells more aromatic than it tastes because of the combined action of orthonasal and retronasal olfaction, which can distinguish thousands of different aromas, while taste can only perceive five water-soluble flavors: sour, sweet, bitter, salty and umami.

Studies have also shown that chocolate and lavender are currently the only two known flavors that produce the same sensation whether entering the nasal cavity or emanating from it.

FrontStreet Coffee Recommendation

Since roast level shapes how much aroma a bean releases, a medium roast is a good place to start if you want a balanced, fragrant cup. FrontStreet Coffee's Jamaica Blue Mountain No. 1, grown from the Typica variety, is roasted to a medium level so its distinct sour, bitter, sweet and full-bodied notes blend into one elegant, inviting whole. On the palate it opens quickly onto chocolate, roasted nuts, cream and caramel, a baked, aromatic character few coffees can match.

If you prefer something fruitier, FrontStreet Coffee's Strawberry Candy is a medium-roast blend of a Costa Rican honey-processed coffee and a Panama washed Gesha. The medium roast brings out both an orange-blossom honey sweetness and a rounded body, and it extracts well as a cold brew, a pour-over or an espresso, with an aroma that lifts the moment it is brewed.

For a gentle, everyday option, FrontStreet Coffee's 2013 Natural Typica carries the classic Yunnan small bean character. Roasted to a medium level to keep its balance and softness, it shows layered notes of nuts, brown sugar, black tea and dried apricot, and works in a pour-over, a cold brew or a drip machine at a very reasonable price.