Of all the arabica coffee varieties, Bourbon is very popular among roasters and drinkers. The most interesting part of Bourbon is probably the color mutation, that results in yellow and pink coffee cherry.
Coffee Berries ripening from Green to Red
Coffee beans are the plant seeds, normally having two inside the coffee fruit that we called cherry. Cherries are green at first, taking months to grow bigger. When dry harvest season come, they start turning from green to red and eventually dark red when fully ripe. Skilled pickers will be able to tell from the reddish level of the cherry whether the cherry is ripe enough to harvest.
Training the pickers on “red” is a day-to-day part of farm operation. Pickers are paid by weight of cherries collected, therefore they tend to believe cherries are red enough. But unripe cherry will affect the cup quality at the end after roasted.
Coffee cherries never turn red?
Now you can tell how excited (and also worried) when the farmer first encounter this natural mutation of Bourbon variety that their cherry never turn red.
Yellow Bourbon Coffee from Brazil
Yellow bourbon was first discover in Brazil. Because of it’s different operational requirement, it’s not too popular when first introduced to the farmers. But the recent developments of specialty coffee drive a different results. Cup quality of Yellow Bourbon has gained really high cupping score in competition. Now good quality of yellow bourbon from Brazil can easily sell 10 times higher than C price.
Researchers have identified the gene that decide the color of the cherry. It is a gene pairing named “Xanthocarpa,” from the Greek xanthus (yellow), and carpus (fruit). The yellow bourbon is generically stabilized. You can see a Bourbon-growing farm with both yellow and red cherries nowadays.
Pink Bourbon Coffee from Colombia
But what’s about if it happens half-half? That’s what the Colombian and El Salvador farmers found in their farm. Some yellow bourbon cherry turn a bit red but not totally. The one first found in Huila department of Colombia is called the Pink Bourbon, which get its name popular in past few years among speciality coffee world.
https://www.cafeimports.com/europe/beanology/view/pink-bourbon-san-adolfo-grainpro-4887
Pink bourbon variety is still relatively difficult to reproduce. This variety is not stable, and farmers reported that some trees will go back to yellow after a while. They need even more care to avoid cross mutation. But the special cup quality of jasmine floral and citrus flavor worth the producers to continue to explore.
More Colourful Bourbon to come
Separating different mutations by cherry color won’t stop. We are now seeing some producers separate lots on other yellow variety, like Caturra, Catui, Typica. It will only be more and more interesting down the road with more and more advancement in genetic research.