What's the Difference Between the Maillard Color Palette and the Maillard Reaction in Coffee Roasting? What About Caramelization?

What is the Maillard Color Palette?

Every autumn and winter season, the "Maillard color palette" always creates a trend! The Maillard color palette refers to the color changes that occur in food during the cooking process due to the Maillard reaction. Brown, tan, orange, and yellow are the main colors of this palette. Coffee beans are also a type of food, so when we roast coffee beans, the Maillard reaction also occurs. So the question arises: what effects does this reaction bring to coffee?

What are the Effects of the Maillard Reaction During Coffee Bean Roasting?

The Maillard reaction is also known as the "Meyna reaction" or "non-enzymatic browning reaction"! It was proposed by French chemist L.C. Maillard in 1912. It refers to the reaction that occurs when sugar compounds with proteins or amino acids are subjected to high-temperature baking. This reaction generates brown or even black macromolecular substances called melanoids, as well as numerous small molecular substances. They cause food to evolve very rich aromatic molecules and diverse color changes. The same principle applies to coffee beans.

The coffee bean roasting process can be summarized into four main stages: dehydration period, intermediate period, first crack, and second crack. The beginning of the Maillard reaction occurs when the raw coffee beans have completed dehydration. After the Maillard reaction begins to take effect, the beans will lose their original green (or light yellow) color and take on a yellow color. Therefore, this point is often called the "yellowing stage." As the roasting process increases, the yellow gradually transforms into brown. Then, as mentioned at the beginning, besides color changes, the aromatic substances in coffee will degrade and then polymerize due to heat, producing new aromatic substances and compounds. And this process continuously repeats. So aromatic substances will accumulate like a snowball, growing larger and larger! Research has shown that the number of substances evolved at this time reaches as many as 600 types! Floral and fruit aromas are aromatic substances formed during this stage. Therefore, it can be seen that the main effect of the Maillard reaction is to provide rich aromatic substances to coffee beans.

FrontStreet Coffee would like to mention a misconception here: in the coffee bean roasting process, there is another important reaction - the "caramelization reaction," which appears just before the first crack begins. This leads many friends to mistakenly believe that the start and end points of the Maillard reaction are from the yellowing stage to before the first crack begins. But in fact, it starts from the yellowing point and continues until the end of roasting, only that the appearance of the caramelization reaction slows down its efficiency!

What is the Caramelization Reaction in Coffee Bean Roasting?

The caramelization reaction refers to the process where sugar substances, in the absence of amino compounds, are continuously heated above their melting point, decomposing and forming entirely new molecular compounds. This reaction starts at 171°C, which coincidentally is the point when the beans in the roaster are about to reach first crack, which is why FrontStreet Coffee says it occurs before the first crack begins. The caramelization reaction produces the aromatic substance diacetyl in beans, which is the main source of creamy aroma; as well as furan compounds, which are the main source of caramel aroma; and hydroxymethylfurfural, which is the main source of sweet and sour aromas like honey and fruit juice. It also continues to act until the end of roasting! But it's worth mentioning that if roasting is too deep, it will cause excessive caramelization reaction, developing into carbonization, which will lead to very obvious burnt bitterness in the coffee.

When coffee beans begin to crack for the first time, roasting can be ended at any time to remove the beans! The earlier the beans are removed, the lighter the roast degree, and the less the caramelization reaction! With less aroma masking from the caramelization reaction, floral and fruit flavors become more obvious; while the later the beans are removed, the deeper the roast degree of the coffee beans, and the heavier the caramelization reaction! The heavier the reaction, the stronger the nutty, chocolate, and caramel flavors it brings, while also making the coffee texture richer and smoother due to the presence of large amounts of oil~ This is the effect of the caramelization reaction!

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