Why Coffee Beans Need Roasting: Flavor Differences Between Light and Dark Roasted Yirgacheffe Coffee Beans

Coffee is a beverage brewed from coffee beans. FrontStreet Coffee believes that what makes coffee special is that coffee beans need to be roasted before they can be used for brewing. The roasting temperature reaches over 200 degrees Celsius, which is much higher than the roasting temperature for nuts. The duration of roasting determines the depth of the roast, so different roast levels produce different flavors and textures!

The Evolution of Coffee Roasting

Before the third wave of specialty coffee, which was in the 1970s-1990s, specialty coffee didn't exist yet, and commercial coffee beans dominated. If commercial coffee beans were lightly or medium roasted, it was easy to detect defective flavors in the coffee, unclean tastes, or woody flavors from aged beans that had lost moisture. If roasted past the second crack, these undesirable flavors became difficult to detect. This is also why the third wave of coffee popularized light roasting. With improvements in coffee cultivation and post-processing techniques, we can now obtain a cleaner, sweeter cup of coffee that emphasizes regional flavors. Light roasting allows us to taste the origin flavors of coffee. For example, a bean with citrus and floral notes must come from Ethiopia. If everything is roasted to dense second crack, these good flavors are lost.

Why Do Coffee Beans Need to Be Roasted?

Coffee originally starts as seeds within fruits. After processing, they become green coffee beans. Raw coffee beans themselves don't have a distinct coffee aroma. Only after being roasted can we smell the rich coffee fragrance. Therefore, coffee bean roasting is a process of transforming the internal components of the beans. Only after roasting produces components that can release the proper coffee aroma can we smell the coffee fragrance. This is similar to how food produces richer, more enticing aromas after cooking. Different roasting methods will present different flavors in coffee beans.

Maillard Reaction

This reaction occurs at approximately 150°C when the coffee beans are still absorbing heat and continue to release heat during the roasting process. The heat causes reactions between carbohydrates and amino acids in the beans, leading to changes in color, taste, and nutritional components.

The color change is mainly due to the production of melanoids. These numerous substances not only turn the coffee beans brown but also affect the coffee's mouthfeel and body.

Small changes in the temperature and duration of the Maillard reaction stage can have a significant impact on the final flavor.

Coffee that spends more time in the Maillard reaction will increase its viscosity, while a shorter Maillard reaction will produce more sweetness and acidity, because if the Maillard reaction time is too long, fruit acids and acids that would convert to sweet flavors will be destroyed.

When FrontStreet Coffee's roasters experiment with roasting coffee beans, they also change the duration and intensity of the Maillard reaction and record how these changes affect the final flavor.

Caramelization Reaction

When heated to approximately 170°C, heat breaks down large complex carbohydrates into smaller sugar molecules that can dissolve in water, which means the sweetness of the final brewed coffee will increase.

This reaction continues until the end of the roasting process and also contributes to the sweet aromas in coffee, such as caramel and almond notes.

Through the Maillard reaction and caramelization reaction, you can understand how reactions produced during coffee roasting affect the flavor of a cup of coffee. Previously, I heard people say that among the factors affecting a cup of coffee, green coffee beans account for 70%, roast level 20%, and brewing 10%.

Only through the high-temperature environment of roasting can coffee beans develop such intense aromas and rich taste experiences! With the time and temperature of coffee bean roasting, the same coffee beans can present diverse and varied coffee profiles!

Coffee Roast Levels

Generally, they can be divided into three major categories: light roast, medium roast, and dark roast.

However, in terms of subtle taste differences, they are further divided into eight levels: Light Roast to Italian Roast.

Light Roast: Light Roast, Cinnamon Roast - Strong aroma, distinct fruity acidity.

Medium Roast: Medium Roast, High Roast, City Roast - More coffee bean aroma, sweetness, slight fruit acidity, typical Vienna coffee flavor.

Dark Roast: Full City Roast, French Roast, Italian Roast - Strong caramel flavor, rich and intense taste.

The roast level of a coffee bean largely determines the flavor direction of that bean. Coffee bean roasting can be simply divided into three levels: light roast, medium roast, and medium-dark/dark roast.

FrontStreet Coffee Light Roast / Cinnamon Roast

Drop time: From the beginning of first crack to when it becomes dense

Flavor: Bean surface appears cinnamon-colored. At this point, grassy flavors have been eliminated, with strong acidity and slight aroma. Often used for brewing American coffee.

Medium Roast

Drop time: Between dense first crack and its end

Flavor: Bean surface appears chestnut-colored, with light taste, acidic with bitterness, moderate aroma, preserving the original flavor of coffee beans. Often used for American coffee or blended coffee.

Medium-Dark Roast / City Roast

Drop time: After the first crack, between the first and second cracks

Flavor: Bean surface appears light brown, with bright and lively taste, balanced acidity and bitterness with lighter acidity, releasing the premium flavors in coffee. This is the standard roast level and also the most popular among the general public.

Dark Roast / Italian Roast

Dark roast is also known as "Italian Roast"

Drop time: From the end of second crack until the bean surface turns black and oily

Flavor: Bean surface appears black with oily sheen. Before the coffee bean fibers carbonize, the taste is strong and complex, with powerful bitterness and rich roasting and burnt aromas. Mainly popular in Italy, often used for making Espresso.

Light Roast Coffee Bean Recommendations

1. FrontStreet Coffee Yirgacheffe Natural Red Cherry

Flavor description: Overall taste has distinct layers, with prominent aroma, featuring lemon fragrance, floral notes, and fermented wine aroma. Entry has a full juice sensation, with citrus and lemon acidity, weaker nutty flavors, and honey-like aftertaste.

2. FrontStreet Coffee Kenya Assalia

Flavor description: Wet aroma has ripe tomato and floral notes. Entry features cherry tomato and black plum flavors, with bright acidity, clean and most solid and rich texture, like the weight of an African elephant! Mid-section has prominent sweetness with juice sensation, aftertaste has berry fragrance and brown sugar sweetness, with green tea aroma.

3. FrontStreet Coffee Panama Butterfly

Flavor description: Floral, black tea, berry, citrus, with slight nutty notes in the finish. Smooth mouthfeel, low bitterness, moderate acidity, medium aftertaste.

FrontStreet Coffee Brewing Parameters

Coffee dose: 15 grams

Coffee-to-water ratio: 1:15

Water temperature: 90°C

Grind size: Medium-fine grind (78% pass-through rate on #20 standard sieve)

Dripper: V60

FrontStreet Coffee Brewing Method

30 grams bloom for 30 seconds. After bloom ends, pour in circles to 125 grams. Wait until water level drops by half, then continue pouring to 225 grams. Total extraction time is 2 minutes.

Medium-Dark Roast Coffee Bean Recommendations

1. FrontStreet Coffee Golden Mandheling

Flavor description: Multi-layered, clean, balanced, with long-lasting caramel sweetness in aftertaste.

2. FrontStreet Coffee Jamaica Blue Mountain

Flavor description: Blue Mountain has a very clean, very gentle taste with chocolate sweetness and very strong body. Rich and fragrant flavor, with perfect combination of coffee's sweetness, acidity, and bitterness. Completely without bitterness, only moderate and perfect acidity, with persistent fruit notes in the finish.

3. FrontStreet Coffee Brazil Queen's Farm

Flavor description: This is a flavor-balanced coffee with typical Brazilian coffee style. Prominent nutty and chocolate flavors with distinct cane sugar sweetness.

FrontStreet Coffee Brewing Parameters

Coffee dose: 15 grams

Water-to-coffee ratio: 1:15

Water temperature: 86°C

Grind size: Medium-coarse grind (65% pass-through rate on #20 standard sieve)

Dripper: KONO

FrontStreet Coffee Brewing Method

30 grams bloom for 30 seconds. Pour in circles to 125 grams. When water level drops by half, continue pouring to 225 grams. Total extraction time is 2 minutes and 10 seconds.

Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473