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How is the Maillard reaction different from the Maillard reaction when roasting coffee beans? What is the caramelization reaction?

Published: 2026-06-10 Author:

Last Updated: 2026/06/10, Every autumn and winter, "Merad color" always set off a wave of trend! Maillard refers to the color change of food as a result of Maillard's reaction during cooking. Brown, brown, orange and yellow are the main colors of this color system. Coffee beans are also a kind of food, so when we are baking coffee beans

Every autumn and winter, "Merad color" always set off a wave of trend! Maillard refers to the color change of food as a result of Maillard's reaction during cooking. Brown, brown, orange and yellow are the main colors of this color system. Coffee beans are also a kind of food, so when we are roasting coffee beans, we also have a Merad reaction. So the question is: what effect will this reaction have on coffee?

What is the effect of Maillard reaction when roasting coffee beans? Maillard reaction (Maillard reaction) is also called "Mena reaction" and "non-enzymatic browning reaction"! It was proposed by French chemist L.C.Maillard in 1912. It refers to the reaction of sugars with proteins or amino acids when they are baked at high temperatures. The reaction will produce brown or even black macromolecular substance melanin-like substance, as well as most small molecular substances. They will give food a very rich aroma molecules, as well as a variety of color changes. The same goes for applying it to coffee beans.

The roasting process of coffee beans can be summarized into four main stages: dehydration period, relay period, first explosion and second explosion. Maillard's reaction begins when the dehydration of raw coffee beans is completed. After the Maillard reaction begins to take effect, the beans will fade from their original turquoise (or light yellow) and dye them yellow. Therefore, this node is often called "yellowing stage". As the baking process increases, yellow will gradually change to brown. Then, as mentioned at the beginning, in addition to the change in color, the aroma substances of coffee will be degraded and repolymerized by heat to produce new aromatic substances and compounds, and this is repeated over and over again. So the aromatic substances will snowball like more and more! The study shows that the number of substances evolved at this time is as high as more than 600 kinds! The fragrance of flowers and fruit is the aromatic substance formed at this stage. Therefore, it can be seen that the main function of Maillard reaction is to provide rich aroma substances for coffee beans.

Qianjie would like to mention a misunderstanding here, that is, there is another important reaction in the roasting process of coffee beans-the "caramelization reaction", which occurs when the explosion is about to begin. This has led many friends to mistakenly believe that the beginning and end of Maillard's reaction is in the yellowing stage and before the explosion begins. But in fact, it starts from the yellowing point and lasts until the end of baking, but its efficiency is slowed down by the emergence of caramelization.

What is the caramelization reaction when roasting coffee beans? Caramelization means that sugars are continuously heated above the melting point in the absence of amino compounds to decompose and form brand-new molecular compounds. The reaction begins at 171 °C, which happens to be the node where the beans are about to explode in the furnace, which is why Qianjie says it will happen before the explosion begins. Caramelization causes beans to produce the aromatic substance diacetyl, which is the main source of cream aroma; furan compounds, which are the main source of caramel aroma; and hydroxymethyl furfural, which is the main source of sweet and sour aromas such as honey and fruit juices. It also works to the end of the baking! But it is worth mentioning that if roasted too deeply, it will cause caramelization to overreact and develop into carbonization, which will lead to a very obvious bitter taste of coffee.

When the coffee beans start in an explosion, you can end the baking at any point in time and let the beans out of the oven! The earlier the baking time, the lighter the baking degree of the beans, the lighter the baking degree, the less the caramelization reaction! Without the aroma masking brought by the caramelization reaction, the flower and fruit flavor is more obvious, while the later the baking is, the deeper the roasting degree of the coffee bean is, and the more serious the caramelization reaction is! The heavier the reaction, the heavier the flavor of nuts, chocolate caramel and so on. At the same time, it will make the coffee taste more mellow because of the existence of a large amount of fat. This is the role of caramelization! -END-

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FrontStreet Coffee is a long-established specialty coffee roaster in Guangzhou China, selling freshly roasted beans from its own farm in Yunnan as well as dozens of carefully selected single-origin beans from around the world for both pour-over and espresso. The products deliver consistently excellent quality and great value, with shipping within 24 hours. Guangzhou’s FrontStreet Coffee shop is recommended by many coffee lovers, and the beans are now available online at the Tmall 。