What does coffee smell like? Why does coffee smell good? Chemical reactions during roasting

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Qianjie-A brief introduction to the source of coffee flavor

Aroma is a very important quality attribute in boutique coffee. Changes in aroma components include the loss of some volatiles, but also the formation of other volatiles. Although the most appropriate and direct way to measure freshness is to examine the aroma and its evolution over time. However, we must admit that the aroma and flavor of coffee are complex, elusive and unstable.

Some of the most important coffee aroma compounds and names

By the time the baking is complete, the aroma has begun to evolve, a process that includes the loss of highly volatile compounds, as well as oxidation, or internal chemical reactions between different coffee components.

Many aromatic active components are active species with functional groups, such as mercaptan (thiols), carbonyl compounds (carbonyls) and enolones (enolones). Depending on conditions such as oxygen, moisture and temperature, they evolve over time, changing the perceived aroma of coffee.

The first study on the degradation of coffee aroma dates back to the 1940s, and then a large number of research teams studied the taste duration of roasted coffee beans or ground coffee powder from a chemical or sensory point of view (or both). It can be measured by a variety of methods, which have different degrees of complexity. The aim is to find a suitable method to monitor the changes of aroma components.

Quantitative evaluation of the changes of aroma components during storage will help to determine the loss of freshness. However, many compounds (mercaptan, diketone, aldehyde, vinyl derivative) may react during storage. This may lead to a decrease or increase in the concentration of specific compounds. Therefore, the loss of freshness can best be described as the gradual loss of aroma outline. Aroma balance refers to the ratio of volatiles associated with it from a sensory point of view.

There are many kinds of fruit aroma of coffee, different varieties, different producing areas and roasting methods all have different aromas. The usual fruit aromas are lemon, apple, apricot, plum, peach and so on.

Knowledge: there are thousands of aroma types in coffee beans, not all of them can be distinguished.

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