How Does Barrel Fermentation Change Coffee Beans?

Finca San José in Caldas, Colombia, ages Castillo variety coffee in rum barrels, a process often wrongly credited to Honduras. The farm sits at roughly 1,750 meters on 222 hectares, with most plots facing the sun and soil enriched by the Nevado del Ruiz volcano. The result is a cup with rum, nut and tropical fruit notes across hot and iced pour-over.

Brewing follows staged extraction: grind size, water temperature, dose and ratio are adjusted through the pour so the coffee beans process releases wine-like coffee aroma without harshness. The farm picks cherries to its own standard and the Castillo variety holds up to the barrel treatment, which is why the profile stays layered rather than muddy.

The barrel fermentation process was not pioneered in Honduras; its inspiration came from a sudden flash of insight by the lady owner of Finca San Jose in Colombia. Front Street Coffee takes you deep into the origin background, processing technique, and Castillo variety characteristics of this rum barrel fermented coffee bean, and shares the complete parameters and staged extraction method for both hot pour-over and iced pour-over. From roasting curve to grind size, water temperature, and coffee-to-water ratio, we break down in detail how to brew a cup of San Jose coffee with rich wine aroma and complex layers, experiencing the unique flavors of rum, nuts, and tropical fruits interwoven together.

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When it comes to barrel-fermented coffee beans, the Honduras Sherry whisky barrel beans are probably the most widely known, and that intense whisky aroma is unforgettable to everyone who has tasted it. However, many people mistakenly believe that barrel fermentation technology originated in Honduras. In fact, the creative source of this processing method was an idea that suddenly occurred to the lady owner of Finca San Jose in Colombia one day. Front Street is also full of interest in what exactly barrel fermentation is as a processing method, so let's explore it together with Front Street.

Front Street Coffee (FrontStreet Coffee) — Colombia Rum Barrel Fermented Coffee Beans

Region: Colombia, Caldas

Farm: Finca San Jose

Altitude: 1750m

Variety: Castillo

Processing method: Rum barrel fermentation

Caldas Coffee Region, Colombia

When talking about Colombia's specialty coffee regions, most people first think of Huila or Cauca, while the Caldas region is rarely mentioned. In 2011, this region was listed by UNESCO as a Colombian cultural heritage site, and it is also the area where coffee was first produced as a crop. Finca San Jose covers 222 hectares, located in the central mountainous area, at an altitude between 1350 and 1470 meters. The vast majority of the planted area on the farm faces the sunlight.

Nourished by the Nevado del Ruiz volcano, the farm's soil is fertile, and the year-round temperature stays between 21°C and 25°C. The farm has established its own comprehensive coffee cherry harvesting standards: coffee cherries suitable for picking must be ripe to a slightly purple state, and the harvest period is concentrated in the second and third harvest seasons of the year. Caldas, Quindio, and Risaralda together form Colombia's "Coffee Triangle," and the three regions combined produce most of the country's coffee. Coffee from the Caldas region exhibits clear vanilla notes, soft acidity, and a full body.

Introduction to Finca San Jose

Finca San Jose is a family business founded in 1963. It is currently managed and operated by the third generation of the family, and the shared goal of all members is to ensure the natural environment and resources receive the fullest protection: maintaining planting diversity, preserving the reproduction of local animals, safeguarding water sources and irrigation systems, and introducing more advanced equipment and systems so that the local community can both continue its traditions and achieve development. At Finca San Jose, all efforts revolve around one purpose — producing good coffee.

In the recent wave of vigorous specialty coffee development, Colombia's Finca San Jose Estate has always actively sought breakthroughs, hoping to forge a path different from the rest. One day, while accompanying her husband (who is engaged in making rum oak barrels and brewing rum) as he filled rum distillate for fermentation, the lady owner Monsalve Botero suddenly thought: if green coffee beans were placed in oak barrels to ferment, would a different flavor be produced? So, starting in 2013, Monsalve Botero began experimenting with Colombian oak barrels of different aging lengths, combined with different fermentation durations, for wine-style low-temperature fermentation. Eventually, in this year's batch, she found the ideal flavor, producing a refined washed · rum barrel fermented bean that is different from ordinary traditional washed coffee.

The Rum Barrel Fermentation Process

After the coffee cherries are depulped, they are washed and undergo fermentation for no more than 20 hours, then first dried in a SILO to the target moisture content, and afterward naturally dried outdoors under rain cover until completion. For the special rum barrel fermented batches, the coffee beans processed as above are selected through screens, with 17/18 mesh beans chosen, and then placed in rum barrels that have been used for more than 8 years and are full of "Tafia" aroma, where they rest for 3 months. During this period, samples are taken every thirty days for analysis, and the only goal to be achieved is for the coffee beans to absorb and present the flavor of rum.

What variety is Castillo?

Castillo is the result of five generations of crossbreeding and selection between the Timo and Caturra varieties: Timo is a natural cross between Arabica and Robusta, with a tall plant and resistance to leaf rust. Caturra is the result of a natural mutation of Bourbon, with a short plant and higher yield than Typica and Bourbon. It well inherits Bourbon's high-quality flavor, allows for small plant spacing and denser planting per unit area, but is susceptible to leaf rust.

How does Front Street roast this coffee bean full of rum aroma?

Charge at a drum temperature of 190°C, heat power 140, damper opened to 3; turning point at 1'42", when the drum temperature is 140°C open the damper to 4, heat power unchanged; when the drum temperature reaches 151.8°C the bean surface turns yellow, the grassy smell completely disappears, and it enters the dehydration stage; when the drum temperature reaches 150°C, adjust the heat power to 120, damper unchanged. At 8'38", ugly wrinkles and dark streaks appear on the bean surface, and the toasted bread smell clearly turns into coffee aroma, which can be defined as the prelude to first crack. At this point you need to listen clearly for the sound of first crack. First crack begins at 9'07", open the damper to 4, develop for 2'10" after first crack, and drop at 195°C.

Front Street Coffee (FrontStreet Coffee) Brewing Sharing!

This San Jose coffee bean has a rich wine aroma, so whether made as a hot pour-over or iced pour-over, it is a very good choice. In order to give this coffee bean more layered flavors, Front Street chooses the V60 dripper to brew these beans, because the V60 dripper's spiral ribs extend all the way to the dripper's outlet, and combined with staged extraction this can effectively enhance the sense of layering.

First, let's share the parameters for hot pour-over

Dripper: Hario V60

Coffee-to-water ratio: 1:15

Dose: 15g

Water temperature: 91°C

Grind size: fine granulated sugar (80% passing through a No. 20 sieve)

Front Street Coffee (FrontStreet Coffee) staged extraction method: First use 30g of water to fully wet the coffee bed into a "hamburger" shape and bloom for 30s; for the second pour, at 1 minute 00 seconds on the timer, pour water until 125g, then stop and wait for the water level to drop to 2/3 of the coffee bed before pouring the third stage; for the third stage, at 1'40" on the timer, pour water until 225g, and after the coffee liquid has completely dripped through, the total extraction time is 1'59". After extraction is complete, gently swirl, and wait until the coffee liquid is fully uniform before tasting.

Hot pour-over flavor of San Jose coffee beans: It smells of rich fermented wine aroma, and tastes of rum, nuts, tropical fruits, cream, and oolong tea, with obvious sweetness and an overall balanced profile.

Next is the parameter sharing for iced pour-over

Dripper: Hario V60

Coffee-to-water ratio: 1:10

Dose: 15g

Water temperature: 91°C

Grind size: slightly finer than fine granulated sugar (82% passing through a No. 20 sieve)

Ice: 100g

Because ice cubes need to be added for dilution, the coffee-to-water ratio should be reduced, and the coffee bean grind size should also be slightly finer.

Similarly adopt staged extraction: use 30g of water for a 30-second bloom, then pour in a small stream in circles until 90g for the stage break; when the water level drops and is about to expose the coffee bed, continue pouring until 150g and stop; when the water level drops and is about to expose the coffee bed, remove the dripper, (timing starts from the beginning of the bloom) with an extraction time of 1'25", then add 100g of ice cubes, stir thoroughly until uniform, and then taste.

Iced pour-over flavor of San Jose coffee beans: The fermented wine aroma on the nose is not as obvious as with hot pour-over. On the palate, the rum aroma and the soft acidity of tropical fruits arrive hand in hand, followed by nutty aroma, with high sweetness and a smooth mouthfeel.

The above content is compiled by CoffeeHunters, a coffee news website.