Caramelization (caramelization, oxidation and browning of sugars) during coffee roasting

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Qianjie Coffee shares the caramelization reaction (caramelization, oxidation and browning of sugars) during coffee roasting with Mena.

Most of the time we always say that coffee smells good, so where does the aroma of coffee come from? In fact, coffee beans themselves store a variety of raw materials, such as carbohydrates, proteins, lipids, organic acids and so on. After heating and baking, it will start a series of complex reactions, creating an attractive aroma. There are two reactions in baking that have to be mentioned.

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 sucrose in raw beans provides the materials needed for these two reactions. Previous studies also found that there was a positive correlation between sucrose content and coffee bean flavor.

The slight change of temperature and time length in Maillard reaction will have a great influence on the final flavor of coffee.

Long-term Maillard reaction will increase the viscosity of coffee, and relatively short-term Maillard reaction will bring more sweetness and acidity to coffee beans. This is because the fruity and sweetness brought by acidity in coffee can be destroyed by Maillard reaction for too long.

Caramelization reaction

The sugar in the coffee bean is caramelized at about 170-200 ℃, which is exactly the melting point of sucrose (185 ℃) and the temperature of the explosion stage when the coffee bean is roasted. The product of caramelization is divided into two parts:

The dehydration products of sugar are caramel or sauce-colored pyrolysis products, mainly volatile aldehydes and ketones.

Generally speaking, fire-roasted aroma, caramel and color are produced in the caramelization reaction, as well as other aromatic substances such as maltol, Cyclotene, furan and so on. These compounds can also be found in red wine, fruit juices, cream and other foods.

However, if the caramel is too much in the process of baking, it will cause carbonization and make the coffee dry and choking. If the caramel is not enough, it will make the aroma monotonous and lack of layers.

But if the Maynard reaction and caramelization degree are just right in the coffee, the high-quality acid in the coffee is retained, which can best reflect the flavor of the coffee bean itself.