What Is Coffee Aroma?

Wake up and smell the coffee, the saying goes. The aroma of coffee entices us to drink our java but just what is coffee aroma? The tongue tastes sweet, bitter, salty and sour. The rest of what we call taste comes from aroma and coffee has lots of it. Coffeeresearch.org tells us all about coffee chemistry and coffee aroma.

Coffee aroma is 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 to specialty coffee. Even instant coffee has 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.

It seems like every year more and more aromatic chemical compounds are discovered in coffee. The count today is more than 800 of these. However we don’t experience most of these. The coffee aroma we experience is based on the following:

How strong is the aroma of the compound?
How much of the compound is in your coffee?
How receptive are you to that particular aroma? This is known as the odor threshold.

What compounds provide the most aromas and what aroma do we experience from them? These are the big four in descending order.

Furans: These compounds come from the breakdown of sugars in the coffee bean during roasting and result in a caramel-like aroma.

Pyrazines: These compounds are responsible for cereal, roasted, cracker, toast-like walnut aromas in coffee.

Pyrroles: The sweet, caramel-like and mushroom-like aromas in coffee can come from these compounds.

Thiophens: If your coffee has a meaty aroma it probably comes from the breakdown of amino acids and sulfur in these compounds.

These are complex chemical compounds. For example, guaiacol which gives coffee a phenolic and spicy aroma has this chemical structure and chemical names.

C7H8O2, 2-Methoxyphenol

Synonyms: o-Hydroxyanisole; Guaiacol; guaicol; o-methylcatechol; pyroguaiac acid; pyrocatechol monomethyl ether; Catechol monomethyl ether; Hydroxy-2-methoxybenzene; 1-hydroxy-2-methoxybenzene; Methyl catechol

Aroma and Much More

The aromatic compounds in coffee provide the smell of the coffee and the taste but many of these compounds are also the antioxidants that make coffee so healthy.

Recent research shows that organic coffee antioxidants include chlorogenic acid lactones and lipophilic antioxidants. Chlorogenic acid lactones and lipophilic antioxidants are capable of protecting nerve cells when challenged with hydrogen peroxide.

Scientific American has a cute video entitled The Universe in a Cup of Coffee in which it mentions several compounds that provide the aroma in coffee.

That rich coffee aroma rises from the steam because roasting coffee beans converts bitter chlorogenic acid into a diverse set of compounds. Some smells you’d expect-fruity, spicy, earthy, vanilla-but there are a few surprises (cabbage??). And adding a splash of milk or sprinkle of sugar sets off a chain of physical reactions. Convection makes the cold milk sink while the interactions between milk and coffee molecules create the milky swirls. Brownian motion also will spontaneously mix the coffee over time, no need for a stirrer.

Pyrazine gives coffee an earthy smell. Methylpropanol is responsible for fruity and spicy aromas. Vanillin gives us the vanilla aroma in coffee. Methional is responsible for any baked potato aroma in your coffee. If your coffee has a bit of a cabbage odor you can blame methanethiol. It is in the roasting that most of these compounds are created

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