Coffee beans need to go through several processes to become the delicious taste we are familiar with. The brown coffee beans with a rich aroma are usually the result of roasting, and the color and smell of green coffee beans are completely different. So, what makes roasted coffee different in color, aroma and taste from green coffee? The answer is a chemical reaction called Maillard.
The Maillard reaction is a chemical reaction that occurs between amino acids and reducing sugars; almost all cooked foods with a distinct brown color are the result of this reaction - including steak, different kinds of bread, caramel, and of course, coffee. The reaction is named after the French chemist Louis Camille Maillard, who first record it in 1912.
This reaction takes place between 284 and 329°F (140 and 165°C), breaking down starch into monosaccharides, which undergo discoloration and flavor transformation, and are more intense in an alkaline environment - which is why the flavor of the salt and pepper butterfly circle is so strong. Wikipedia explains it well: "The reactive carbonyl group of the sugar reacts with the nucleophilic amino group of the amino acid and forms a complex mixture of poorly characterized molecules responsible for a range of aromas and flavors. This reaction is the basis for many of the flavoring industry's recipes. ”
Needless to say, to some extent for consumers, controlling food flavor is very beneficial in the food industry. This reaction is present in many foods and is unknowingly consumed by different populations and age groups.
The Maillard reaction should not be confused with simple food browning - browning can also occur at room temperature and is sometimes unwelcome, such as the browning of a sliced apple, and the browning of food without human intervention .
Here are some examples of Maillard discoloration and flavoring: toast, steak and roast, pretzel, certain breads, condensed milk, maple syrup, and of course roasted coffee.
Roasted coffee and cafestol
Coffee is the most consumed beverage in the world (after water). Coffee cultivation first appeared in southern Arabia, and the earliest evidence of coffee brewing appears in the mid-15th-century Sufi shrine, which is now Yemen. Coffee has a rocky history, having been banned in many Christian communities and in Ottoman Turkey for political reasons in the 17th century. The world's largest coffee producer today is Brazil, followed by Vietnam and Colombia.
However, few people know that coffee berries go through several processing steps before becoming roasted coffee as we know it. After coffee beans are harvested (by hand or by machine), they may undergo two processing methods:
1. Sun processing, simple process and low labor intensity;
2. In the water washing process, the coffee needs to be fermented to produce a coffee with a unique and milder flavor. After fermentation, a copious amount of fresh water is rinsed to remove the fermentation residue, which produces a lot of waste water; the green coffee beans are then dried, usually on a trellis—and only after that, they can be roasted.
Treated coffee is roasted, with few exceptions, and all coffees are roasted before drinking, a process that alters the physical and chemical properties of the beans. First, losing moisture, adding volume, and the density of the coffee can also affect the strength and packaging requirements of the coffee.
During roasting, the caramelization reaction occurs as the high temperature breaks down starch into simple sugars, changing the color, aroma and flavor of the beans. Other reactions are also included: In roasting, aromatic oils and acids fade, which affects flavor: at 401°F (205°C ) other oils start to form, one of which is cafestol, at about 392°F (200°C) - and cafestol is what makes coffee smell like coffee.
Then you already know that roasted coffee (cooked coffee beans) is very different from green ones. The Maillard reaction breaks down starch into monosaccharides, and the browning of monosaccharides begins to change the flavor. As the temperature rises, cafestol begins to form, which is not a single oil, but a general term for the origin of coffee aromas - a very complex aroma that is known to contain nearly 850 different volatile compounds, and it takes a lot of chemicals to create a great drink - so drink it in moderation.