How does coffee aroma come from? What is the Mena reaction in coffee roasting?

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Caramel and Mena reaction

The aroma of coffee comes from the fact that coffee beans themselves store rich precursors of aroma substances, such as carbohydrates, proteins, lipids, organic acids, etc. After being heated and baked, it will initiate a series of complex reactions, creating an attractive aroma. The two important reactions are caramelization (caramelization, oxidation and browning of sugars) and Mena reaction (Maillard reaction, reaction of amino acids with sugars). Both reactions require the participation of sugars, and the rich sugar in raw beans provides the materials needed for these two reactions. Studies have also shown that there is a positive correlation between sucrose content and the aroma of coffee beans. Because the sugar content of Arabica mentioned in the previous paragraph is more than Robusta, it also proves the reason why Arabica coffee beans have a better flavor.

Caramelization and Mena reactions each produce the following aromas:

Caramelization: sweet, sour, bitter, fruity, cream, caramel, nuts

-Mena reaction: salty, floral, nutty, chocolate, potato and earthy

The product of the reaction of caramel with Mena is divided into two parts:

a. The source of dark brown coffee beans-the dehydration product of sugar, which is caramel or sauce.

b. The source of coffee bean aroma-lipid pyrolysis products, mainly some volatile aldehydes, ketones, furans (small molecular odors).

Caramelization: sweet, sour, bitter, fruity, cream, caramel, nuts

Mena reaction: salty, floral, nutty, chocolate, potato and earthy

However, if caramel is too much in the process of baking is not a good thing, but will cause carbonization, making the coffee bitter and dull. In addition, it should be noted that coffee beans are rich in fat, so they are not stored properly. The oxidation and cracking of these fatty acids will produce an unpleasant fuel consumption smell, which will greatly reduce the flavor.

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