Yellow Bourbon is a Bourbon mutation whose cherries ripen to yellow instead of red, found in Brazil in the early twentieth century.
The sweetness
Widely regarded as Brazil’s sweetest variety, with a rounded, low-acid, honeyed character. Mogiana and Mantiqueira Yellow Bourbon in particular can be genuinely delicate.
The picking problem
Ripeness is judged visually, and a yellow cherry going from underripe to overripe is much harder to read than a green cherry turning red.
That costs precision at harvest, and it is why some producers avoid it despite the cup.
Where it grows
Brazil principally, with plantings in Central America.
Brewing it
Filter at light to medium roast, or espresso where the sweetness carries through milk.