Top 3 Reactions Every Roaster Needs to Know
The art of roasting is a complex process that significantly affects the flavor, aroma, and body of the coffee. Roasters need an understanding not only of how to utilize their tools but also at a molecular level to consistently create delicious cups. Even minor alterations made in temperature and time can result in drastic differences between roast profiles; thus, they must be attentively monitored while creating each cup!
A cup of coffee's flavor is determined by chemical reactions, and we'll tell you exactly which ones!
The Maillard reaction changes the color and aroma of coffee
The renowned Maillard Reaction, named after the French doctor Louis Camille Maillard, adds that unmistakable brown hue and aroma to your morning cup of coffee. It's also responsible for the irresistible golden-brown crusts of freshly baked bread or those delicious charred bits on a grilled steak. This series of chemical reactions was first documented in 1910 by Dr. Maillard himself!
Louis Camille Maillard © en.wikipedia.org
To begin the process, temperatures are set at approximately 280°F (138°C). This high heat causes a reaction between carbohydrates and proteins in the grain - nitrogen from amino acids binds to the carbon backbones of sugar molecules and releases water vapor. As a result, this affects coloration, flavor profile as well as nutrient content.
The discoloration of the beans is attributed to melanoidins, large molecules that bestow coffee its brown shade and can bring a toasty and bready flavor as well as an unpleasant bitterness. Moreover, these Molecules have a major contribution to the formation of creamy foam when one brews espresso.
Melanoidins influence the formation of cream in espresso
The Maillard reaction plays an essential role in determining the flavor of the coffee. The longer it takes place, the more melanoidins are produced, acids are destroyed, and a darker and denser cup is achieved.
Strecker degradation helps coffee become more fruity
Named in honor of the German chemist Adolf Strecker, this reaction stands as a testament to his scientific contributions.
Through the Maillard reaction, amino acids and carbonyl group molecules interact to give rise to aromatic aldehydes and ketones. This chemical process is what ultimately produces coffee's unique fruity flavor!
Roasters often combine Maillard Reaction and Strecker Degradation into a single process due to their correlation. To modify the flavor, aroma, and overall profile of your coffee, you can alter the length of each reaction as discussed in our article here. Strecker's chemical process imparts unique and distinguishing aromas of fruit to coffee, which is caused by the production of aldehydes.
Caramelization increases the sweetness of coffee
When the temperature rises above 338°F (170°C), complex carbohydrates begin to disintegrate into smaller sugar molecules that can mix with water. This process of roasting enhances coffee sweetness and brings out delectable caramel and nutty flavors on your palate. Roasted beans continue to grow in depth until all phases of the roast conclude.
Sweetness is extracted from coffee beans through the caramelization process that transpires during roasting.
Why is it important to know
As a roaster, it is essential to comprehend how certain chemicals transform and interact at different temperatures throughout the roast. Through careful adjustment of temperature and timing during various stages, one can manipulate the flavor profile in desired ways. By exercising knowledge of chemical reactions that occur within each step of the process, you too can achieve those delicious coffee flavors!