What Water Temperature Should Be Used for Brewing Colombian San José Rum Barrel Fermented Coffee?

Yesterday, FrontStreet Coffee introduced the rum barrel processed beans from Colombia's San Jose Estate. So what water temperature should be chosen for brewing? What flavors will emerge when brewing with high temperature, given this bean's rich aroma?

Meet Today's Star: Colombia San Jose

Before starting our experiment, FrontStreet Coffee would like to introduce today's protagonist - Colombia San Jose.

This bean's processing method is refined washed rum barrel fermentation: after removing the coffee fruit's skin, it is placed in aged oak barrels for low-temperature fermentation, followed by washed processing, and finally dried on sun-drying racks. This unique processing method gives this bean a rich wine aroma.

During cupping, it presents flavors of rum, liquor-filled chocolate, tropical fruits and maple syrup.

Brewing Experiment

FrontStreet Coffee selected three water temperatures for brewing: 92°C, 90°C and 88°C. This experiment only changed the water temperature, while keeping other parameters and techniques as consistent as possible.

Parameters: Hario V60 dripper, 15g coffee grounds, medium-fine grind (BG 6M: 58% pass-through rate on China standard #20 sieve), 1:15 coffee-to-water ratio, segmented extraction.

Water Temperature: 92°C

Bloom with 25g of water for 30 seconds, pour in small circular motions to the center until reaching 126g, then segment. When the water level is about to expose the coffee bed, continue pouring with a slightly larger flow until reaching 226g. Remove the dripper when the water level is about to expose the coffee bed (timing starts from bloom). Extraction time: 1'40".

Flavor: Rich fermentation aroma on the nose, with chocolate and caramel flavors and soft fruit acidity in taste, with a slight smoky note.

Water Temperature: 90°C

Bloom with 27g of water for 30 seconds, pour in small circular motions to the center until reaching 125g, then segment. When the water level is about to expose the coffee bed, continue pouring with a slightly larger flow until reaching 226g. Remove the dripper when the water level is about to expose the coffee bed (timing starts from bloom). Extraction time: 1'43".

Flavor: Rich fermented wine aroma on the nose, with rum, nuts, tropical fruits, dark berries, cream and oolong tea notes in taste. Noticeable sweetness, overall balanced.

Water Temperature: 88°C

Bloom with 28g of water for 30 seconds, pour in small circular motions to the center until reaching 125g, then segment. When the water level is about to expose the coffee bed, continue pouring with a slightly larger flow until reaching 226g. Remove the dripper when the water level is about to expose the coffee bed (timing starts from bloom). Extraction time: 1'42".

Flavor: Light fermentation aroma on the nose, with chocolate, nuts, citrus, jackfruit and tropical fruit flavors in taste. The overall flavor profile leans more toward fruity notes.

Conclusion

Comparing the San Jose brewed with three different water temperatures, the coffee brewed at 88°C shows more fruity acidic notes, while 90°C water temperature better expresses this bean's sweetness and balance.

FrontStreet Coffee recommends choosing water temperatures between 88°C-90°C for brewing this bean. Why not recommend brewing with higher temperatures? Because this bean is medium-roasted and has undergone deep fermentation, making the bean structure more porous. Using water temperatures that are too high during brewing can therefore easily lead to over-extraction.

FrontStreet Coffee Recommendation

Barrel fermentation rewards careful brewing, and Colombia gives you plenty of ways to explore it. FrontStreet Colombia Huila is a medium-dark roasted washed Colombian that highlights black chocolate and nutty sweetness with moderate crema and a full body; it suits pour-over and French press and also extracts well in a moka pot or espresso machine for americano and latte. If you want the same layered sweetness without the rum-barrel character, this is the easy, everyday choice. For a fruit-forward, experimental Colombian cup, try FrontStreet Colombia Frontera Estate Cielo, an anaerobic natural lot: the low-oxygen fermentation converts the beans into richer tropical fruit aromas, and a medium-light roast yields intense, complex notes of passion fruit, grape, apricot and dried fruit in pour-over, cold brew, drip bags or a moka pot.

When brewing deeply fermented coffees, keep the water temperature moderate, around 88-90°C, as the beans are more porous and too much heat quickly leads to over-extraction. A medium-fine grind and a gentle, steady pour will keep the cup sweet and balanced, letting the fermentation aroma and fruit acidity sit alongside the chocolate and nutty notes.