What is Anaerobic Double Fermentation Processing? How to Make Colombian "Rose Valley" Anaerobic Fermented Coffee

Professional coffee knowledge and more coffee bean information — a closer look at one of the most talked-about processing methods of recent years.

FrontStreet Coffee Introduces the Anaerobic Processing Method

The anaerobic processing method stands apart from the three traditional processing methods. Hand-picked, bright red coffee cherries are placed into stainless steel containers, carbon dioxide is injected into the barrels, and the CO2 isolates the oxygen so the coffee can ferment with beneficial microorganisms. Throughout the entire process, humidity, temperature, and gas are all controlled. Some people also call it the whole-fruit anaerobic processing method.

FrontStreet Coffee · Colombia Rose Valley

Colombian coffee is one of the few single-origin coffees sold worldwide that carries a country's name, and in overall quality it has earned praise few other coffees can match. Compared with other producing countries, Colombia invests more in developing products and promoting production — and it is precisely this, combined with superb geographical and climatic conditions, that makes Colombian coffee high-quality, delicious, and world-renowned.

Colombian coffee has strong regional character. The country's coffee areas sit in the Andes Mountains, where the climate is mild and the air humid.

Colombia has three Cordillera mountain ranges running north to south, extending right into the Andes, and coffee is planted along their highlands.

The mountain terraces create a diversity of climates, so it is harvest season somewhere in the country year-round, with different coffee types ripening in succession. Fortunately, unlike Brazil, Colombia doesn't have to worry about frost. These beautiful beans grow with refinement and elegant poise — like pampered children wearing jade pendants — boldly abundant in every part, freely absorbing the essence of heaven and earth, growing peacefully, season after season, in those Andes Mountains.

La Granja Estate is located in the Santander region of Colombia. The farm owner, Vargas, has been growing coffee at La Granja for 20 years. Only fully mature, bright red cherries are selected for picking. Through washing, defects and off-flavors from anaerobic fermentation are removed, and the beans are placed in special enzyme groups for fermentation. Great attention is also paid to drying: avoiding excessive temperatures and adopting a slow drying method. This FrontStreet Coffee Colombia Rose Valley lot uses the anaerobic dual-enzyme washed processing method.

Anaerobic fermentation is a processing method that has seen growing use in recent years. Carbon dioxide is injected into a sealed container to expel the oxygen inside. In this oxygen-free environment, the decomposition of sugars in the fruit pulp slows down, and the pH drops at a slower rate too, extending the fermentation time and developing better sweetness and more balanced flavors.

Dual anaerobic fermented beans have been a major trend over the past two years. This special processing gives the beans a cleaner aftertaste and more distinctive, personalized flavors.

From the moment they hit the grinder, the burrs cut the beans into fine powder. The flavor compounds meet the oxygen and rush across the counter and into the nasal cavity, stimulating every corner of the sense of smell.

Although it is called "Rose Valley," what you actually smell is sweet peach — sweet but never cloying, exactly like the taste of in-season peaches lingering on your lips.

FrontStreet Coffee Recommendation

If anaerobic fermentation's sweetness appeals to you, Brazil — the world's largest coffee producer — is worth exploring alongside it. Brazilian coffee shows moderate acidity and an excellent balance of sweetness, bitterness, and body, which makes it a natural fit for medium roasting: nutty aromas, a mellow mouthfeel, and a whisper of acidity, usable as single origin or in blends. FrontStreet's pulped-natural Cerrado Red Bourbon is the classic entry into Brazil: Cerrado is a renowned growing region famed for high-quality beans, and this Red Bourbon lot, medium-roasted, offers rich aromas of creamy peanut, toast, caramel, and hazelnut with a round, non-acidic body and a light bitter finish — suitable for pour-over, moka pot, espresso SOE, siphon, or French press. FrontStreet's Queen Estate Yellow Bourbon comes from Mogiana near southern Minas, where fertile red volcanic soil feeds the fruit into full, aromatic development; the rare Yellow Bourbon variety, a mutation of Red Bourbon, tastes cleaner in its fruit character, and through pour-over, moka pot, or home espresso machine it reveals a sugarcane sweetness you won't find in other origins, alongside fruit and chocolate notes. Thanks to exactly these qualities — low acidity, balance, and a friendly price — Brazilian beans are also the backbone of many espresso blends: FrontStreet's crema-rich Classic Blend, nut-forward Signature Blend, well-balanced Dark Cocoa Blend, and café-oriented Commercial Blend all contain Brazilian components, which contribute chocolate and cream aromas, a soft balance of sour, sweet, and bitter, and a steadier extraction.