Coffee Roasting Science: What Does Coffee Roasting Mean and How Professional Coffee Shops Roast Coffee

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The Journey of Coffee Aroma

From the farm to your cup, the most crucial element in coffee's journey related to aroma is roasting. We grow coffee trees in tropical regions, condensing the abundant sunlight of the equator into coffee beans, then through the roasting process, transforming grassy and woody notes into caramel sweetness, creamy aromas, and floral-fruity fragrances. Coffee aromas flourish with heat energy, releasing delicate and layered bean scents. When analyzed by scientists using gas chromatography, roasted coffee can contain up to eight hundred different aromatic compounds.

The Art of Coffee Roasting

Examining the aroma descriptions on coffee packaging is like opening a book of aromatic notes. We can experience a lush flower garden, mountain peaks, streams of flowing water, and a pastry chef's pantry. While these different aromatic landscapes originate from specific terroirs and coffee varieties, the roasting technique and degree are key to extracting and balancing these various aromas! Generally, the drop temperature of coffee beans (the final roasting temperature) ranges between 190-230°C (Note: temperatures vary depending on each roaster's design and measurement point), while the duration depends on the desired flavor profile. When heat causes moisture in coffee beans to convert to steam, the rich sugars, proteins, oils, and minerals within the seeds begin to undergo chemical changes. Under high temperatures, the Maillard reaction produces bittersweet amines and various delicate aromas.

Mastering Delicate Aromas

How can we master these delicate, easily dispersed aromas? This is the essence of coffee roasting science. Roasting techniques and timing vary according to each roaster's desired flavor profile. Basically, if roasting time is too short, the various elements within the bean variety don't have time to undergo chemical reactions, resulting in bitterness from incomplete evaporation of astringent polyphenols, while acids from sugar decomposition haven't been broken down by heat, leading to a sour and bitter cup. Conversely, if roasting time is too long, both good and bad aromas will dissipate, replaced by common roasting bitterness that overpowers the coffee's rich characteristics.

Balancing Roasting and Extraction

The balance of roasting time and temperature depends on the bean variety and brewing method, while the coordination between roasting and extraction is a professional science. A barista might choose dark roasting to prolong the flavor of a coffee with intense, bold characteristics; conversely, if given a bean variety with delicate and complex regional flavors, the barista might choose light roasting to avoid the burnt bitterness produced during dark roasting overpowering the bean's original aromatic compounds.

FrontStreet Coffee's Roasting Philosophy

When FrontStreet Coffee decided to start using self-roasted coffee beans, the first decision was the blend formula. After several experiments, this cup combines the smoky depth and nutty aroma of medium-dark roast with a light acidic aftertaste like biting directly into citrus. After finishing, it leaves a subtle yet full bittersweet chocolate note in the mouth. This blend, conceptualized as "Sunlight Journey," uses 100% Arabica beans freshly roasted, delicately combining beans from Colombia, Guatemala, Costa Rica, and natural-processed Yirgacheffe regions. With medium-dark roasting, it adds cocoa notes to the aftertaste. Precise temperature control, warming 25 degrees after the first crack and dropping before the second crack, gives the entire blend more layers, taking you on a sunlight journey through Central and South America in one cup.

The Beauty of Coffee Science

Coffee's aromatic variations are countless, and the process of developing these flavors is a fascinating science involving chemistry, craftsmanship, and culture. Regarding coffee, we have endless aromatic landscapes worth exploring, starting with the cup in your hand. After all, in coffee roasting science, aromatic evaluation is the most enjoyable stage.

Professional Roasting Techniques

Roasting brings out deeper, more delicate flavors from coffee beans. Professional roasters record the temperature, ambient humidity, and air temperature of each roast. Such focused observation aims to better control the flavor of each coffee batch.

Optimal Flavor Development

Roasted coffee beans sealed in airtight bags and stored for three to five days will have more rounded flavors, and should be consumed within one month.

Environmental Factors

Weather, seasons, and humidity all affect the roasting process. For example, coffee beans have different ambient temperatures in winter and summer, so corresponding adjustments during roasting are necessary to maintain consistent product flavors.

Drum Roaster Technology

Drum roasters are common roasting machines where coffee beans rotate in a drum while roasting. Roasting methods can be basically divided into semi-hot air and direct fire types. The former primarily relies on hot air convection to heat the beans, producing more uniform and gentle flavors; the latter has holes drilled in the drum, and beans are mainly heated by direct contact with the drum, producing strong, direct flavors. Both roasting methods involve air convection, mainly to carry away smoke produced during roasting, resulting in cleaner coffee flavors.

The Art of Precision

During the roasting process, the transformation of bean color and aroma happens rapidly, requiring experience to master precisely, thus producing the ideal cup of coffee.

Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473