The flavor characteristics of coffee are actually the products of a chemical compound. Where does the aroma of coffee come from?

There are so many factors in coffee that can affect coffee flavor: variety, roasting method, brewing method, processing method…however, when you start analyzing it, coffee flavor characteristics are actually the product of a chemical compound.

The way we roast coffee, the type of coffee we grow, the height at which we grow it, of course, all have an impact on these compounds. But if we really want to optimize coffee taste, we need to understand the science behind it. (This is especially true for roasters, since your job is to manipulate heat to control several chemical reactions.)

Flavor: Chemical issues

Aroma, flavor, aftertaste, acidity and body-these five attributes are all created by the collision of different compounds. The taste and aroma we analyze with our senses at the cup table are also the effects of chemical compounds. First we smell the dry incense, then the wet incense, and finally we sip and taste it. At each stage, there are different molecules at work.

Some Nonvolatile Compounds You Should Know About

When we talk about non-volatile compounds, we should emphasize alkaloids (caffeine and trigonelline), chlorogenic acids, carboxylic acids, carbohydrates and polysaccharides, lipids, proteins, melanoids and minerals.

Caffeine is soluble in water and affects the strength, bitterness and body of brewed coffee. Another essential alkaloid is trigonelline, which is also a source of aroma in roasted beans and coffee.

Chlorogenic acid: It is important to understand that chlorogenic acids are formed from trans cinnamic acid and quinic acid. Let me explain: quinic acid dominates the bitterness and astringency in coffee and is also the source of these flavors. During baking, chlorogenic acid degrades, which means we feel an increase in quinine acid. This is one of the most important reasons why deep-baked beans taste bitter.

Organic acids: Now let's talk about what good acids are. This is a key attribute of coffee quality and is related to sweetness.

There are some things you should know:

Arabica beans are more acidic than Robusta beans.

As the roasting process progresses, the acid content in coffee also decreases (11% in raw beans and only 6% in cooked beans).

·Deep roasting reduces the amount of acid in coffee and also reduces the perceived acidity.

Now let's look at the types of acidity: some of the more "sensitive" acids in coffee are citric acid, malic acid and chlorogenic acid. Some sour substances degrade during baking (e.g. chlorogenic acid), while others increase in concentration during baking. For example, formic acid, acetic acid, lactic acid, etc.

Carbohydrates and polysaccharides: There are polysaccharides that are present in one form of carbohydrate, such as mannan and cellulose. These sweet compounds play a crucial role in coffee's retention of volatile compounds, which increase coffee aroma. In terms of flavor, these compounds are also related to the body of coffee. Also, glucose and fructose, which are smaller in structure, sweeten coffee.

Lipids help improve the taste of coffee. They are extracted from beans and are also the protagonists of CREMA on the surface of espresso. The roasting process doesn't really affect its content, but in the oven, lipids do seep out onto the surface of the beans.

Finally, we're going to talk about melanoids, which are products of Maillard reactions: reactions between amino acids and carboxyl groups of reducing sugars. They are macromolecules, substances that brown coffee beans and enhance the texture of the brew. This means that the amino acid content of coffee is closely related to its quality, the more amino acids, the more reactions, the more melanoids.

Note, however, that the color of coffee is not only caused by melanoids, it is also the result of caramelization of sugar.

Special compounds, special flavors

What are the volatile compounds? These include hydrocarbons, alcohols, aldehydes, ketones, carboxylic acids, esters, pyrazines, pyrroles, pyridines, furanones, phenols, etc. While these names all sound scientific and maybe a little scary, following them you can trace back to the coffee properties.

I'm sure you've used coffee sniffers, which is what we call "barista noses." A set of 36 bottles filled with essence, a bottle represents 1 fragrance, that is, a total of 36 fragrances, he can be used to guide you, training your sensory skills. Of course, we all like sweet smells, and one of the most popular aromas is "apricot juice", which has a fresh, fresh fruit aroma.

Well, usually, floral and fruity are products of ketones and aldehydes; furans and furanones are usually associated with caramel and roasted coffee flavors; pyrazines are associated with nuts and roasted coffee flavors. Of course, there are other compounds that interact to produce negative odors. Phenols, for example, are phenolic and burn odors.

Although it all boils down to deep and complex areas of science, it helps us make good use of the compounds in coffee itself and make a better cup of coffee.