Why is coffee so attractive after roasting？
A variety of chemical reactions occur during coffee roasting, mainly including the following:
Maillard Reaction: This is a non-enzymatic Browning reaction, involving the polymerization and condensation of compounds containing free amino acids and reducing sugars or carbonyl compounds when heated, and eventually the formation of brown or even brown-black macromolecular substances like melanin or melanoid melanin. Maillard reaction not only gives coffee beans unique flavor and color, but also produces reducing ketones, aldehydes and heterocyclic compounds, which are the main sources of food color and flavor.
Caramelization: starting at about 170 ° C, this is the process of further decomposition of sugars. Caramelization deepens the color of the beans and creates aromas of fruit, caramel, roasted nuts and more. Both this reaction and the Maillard reaction reduce the sweetness in coffee and increase the bitter taste of coffee.
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Pyrolysis: This is the high temperature coking process that completely changes the material inside the raw beans through the quenching of the flame, so that the proteins and sugars in the coffee beans are constantly producing new compounds and recombining to form the aroma and alcohol taste.
Strecker degradation reaction: This is a Maillard dependent process where amino acids react with carbonyl molecules to form compounds such as aldehydes and ketones, which are essential for the production of aroma and flavor compounds.
Oxidation reaction: In the process of caramel pigment production, the products of the Maillard reaction and caramelization reaction may interact to oxidize large molecules, thereby improving the coloring power of the products.
These chemical reactions work together to transform coffee beans from raw beans to cooked beans with rich flavor and aroma.