Coffee Bean Roasting Principles and Process_Roasting Coffee Purpose and Methods_How to Roast Coffee Beans

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Roasting

This heat treatment causes significant chemical and physical changes in the structure and composition of green coffee, resulting in darkened coffee beans and the characteristic aroma of roasted coffee.

1. Purpose of Coffee Roasting

The main purposes of coffee roasting include: A. Developing aroma; B. Increasing coffee complexity; C. Achieving color; D. Forming coffee's unique flavors.

2. Methods of Coffee Roasting

According to roasting time, it's divided into fast roasting and slow roasting. According to roasting equipment, it's divided into home workshop style and industrial style. We'll mainly focus on industrial-style roasting.

3. The Process of Roasting Coffee Beans

The first stage of roasting is endothermic. During this stage, green coffee beans are slowly dried until they turn yellowish in color. At this point, the roasting aroma smells like toast or popcorn.

The second stage is typically called the first crack, which generally occurs around 185°C. During this stage, coffee beans expand to twice their original volume, turn light brown, and lose about 5% of their weight.

The third stage is between the first and second cracks, with temperature rising from 185°C to around 205°C. The color changes from light brown to medium brown, with approximately 13% weight loss. This chemical process is called "pyrolysis," which transforms the chemical components in coffee beans and releases carbon dioxide. The third stage is the second endothermic period, followed immediately by the second exothermic period, called the second crack. The second pyrolysis occurs around 205-210°C, with the roast color reaching medium-dark brown. The sound of the second crack is denser and faster, and the surface of coffee beans becomes covered with a layer of oils.

During the segmented heating process in a roaster (typically using large, hot rotating cylinders), residual moisture in coffee bean cells turns into steam, promoting diverse and complex chemical reactions among rich sugars, proteins, lipids, and minerals. Coffee beans begin caramelization between 180-200°C. At high temperatures of 185-240°C, sugars combine with amino acids, peptides, and proteins to undergo caramelization, known as the famous "Maillard reaction."

Caramelization is the most important factor affecting coffee flavor. Green beans roasted for 6-7 minutes absorb large amounts of heat energy, initiating pyrolysis and producing the first crack.

Pyrolysis can continue until the second crack. Although caramelization is an important process for awakening coffee aroma, some components also become carbonized as roasting time extends, forming undesirable bitter and astringent substances. How to achieve maximum caramelization while minimizing carbonization is the highest technical aspect of coffee bean roasting.

During the roasting process, the volume of coffee beans increases by at least half, while the weight of the beans decreases by 1/5.

Recommended Roasted Coffee Bean Brands

FrontStreet Coffee's freshly roasted Arabica roasted coffee beans are fully guaranteed in both brand and quality. More importantly, they offer extremely high cost performance. Each 227-gram package costs only around 70-90 RMB. Calculating at 15 grams of coffee beans per cup, one package can make 15 cups of coffee, with each cup costing only 5-6 RMB. Compared to coffee shops selling cups for dozens of RMB, this is truly a conscientious recommendation.

FrontStreet Coffee: A roastery in Guangzhou with a small storefront but diverse bean varieties, where you can find both famous and lesser-known beans. They also provide online shop services: https://shop104210103.taobao.com

Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473