Beginner's Guide to Coffee Bean Curing - How to Cure Single-Origin Coffee Beans Without Water and Fertilizer

FrontStreet Coffee - Introduction to Single-Origin Coffee Bean Degassing

After coffee beans are roasted, they go through a phenomenon known as degassing. During roasting the beans expand in volume, and the space that opens up inside them fills with carbon dioxide. A series of other chemical changes occur as well. The most intuitive way to observe them is through pour-over brewing. When you first pour 1-2 times the weight of the grounds in water, the bed begins to expand and forms a small hill on contact with the water. That is the grounds releasing carbon dioxide, and degassing is simply the process of letting that gas out.

As time passes, the carbon dioxide is gradually released while the coffee's flavour also fades. That is why a coffee stored for more than a month may show no hill at all during the bloom.

Why Degassing is Necessary

Freshly roasted coffee is full of vitality, which shows up in extraction: the beans hold abundant gas and expand easily on contact with water.

At this stage the coffee is too active. The crema when making espresso will be rather coarse and dissipate quickly, and when brewed as pour-over or with other methods the flavour will be bright but lacking in body, with an acidity that often feels too sharp. This is when degassing becomes necessary.

Some suggest sealed degassing, others open-air degassing, meaning freshly roasted beans need appropriate contact with air for a certain period.

The length of degassing depends more on roast level and extraction method. For lighter roasts and coffee brewed with filter equipment, generally 1-3 days is enough. For darker roasts and coffee extracted on an espresso machine, 3-5 days are needed.

During roasting, as green beans are exposed to increasing heat and time, the coffee changes from green to yellowish-brown and finally reaches the intended roast level. When the roast rhythm is too fast, the molecular structure breaks down more severely and the roasted beans may carry dry or smoky flavours. Such beans need to rest for several days.

Do all beans need degassing? Of course not. When the roast rhythm is appropriate and the beans have no roasting defects, degassing is not necessary.

Knowledge Point: Degassing must be done in packaging bags fitted with a one-way degassing valve.

FrontStreet Coffee Recommendation

Once your beans have rested, a V60 is a great way to taste them clearly. FrontStreet Coffee's V60 picks are the bright, floral and fruit-forward coffees that benefit from the dripper's fast extraction and the lively acidity it produces. FrontStreet Coffee's Gedingding Yirgacheffe is a fine starting point, with its classic jasmine, citrus and berry notes; Huakui brings a richer tropical fruit aroma; and Strawberry Candy adds a clean Geisha-style floral and fruit character.

If you prefer a heavier cup, FrontStreet Coffee's PWN Golden Mandheling is roasted dark for very low acidity and a thick, long body, full of herbal and dark chocolate aroma with a faint earthy note. FrontStreet Coffee's Brazil Queen Estate is the balanced, lower-acid alternative, with pronounced nut and cocoa aroma and clear caramel sweetness.

Whichever bean you choose, keep the recipe simple: around 15g of coffee, a 1:15 ratio, water a little off the boil and a medium-fine grind, then bloom and pour in stages. Rest the beans 4-7 days from the roast date before brewing for the fullest flavour.