Postby Colleen Anunu » Thu May 30, 2013 8:52 am
Jake,
The flavor of Coffee Leaf Rust may very well be 'unripe'. Even with samples of lots for which producers have sworn to have only picked ripe fruit, I've found the cup profile unripe/immature/not very sweet or dynamic. My guess is that this cup profile occurs because plants are unable to photosynthesize due to the decay of leaves, and therefore sugars in the fruit are not abundant... even though the exterior of the coffee cherry is that blood red or burgundy color.
The course material for GE 255 Organic Acids & the Chemistry of Coffee indicates that sugars are a by-product of photosynthesis, and these sugars (and other photosynthates) are needed for cellular respiration. Cellular respiration is what produces those acid profiles that are so sought after. That's the connection there.
Of course, for those producers that did spray Alto Cien fungicide, or maybe even a more biodynamic option, during the ripening and harvesting stage (rather than earlier in the year or waiting until harvesting was completed), I wonder how residue on the cherry potentially affected water and fermentation throughout the post-harvest processing stages and perhaps made its way into the cup. Most of the producers I spoke with advised against that practice, and some speculated that whether residue would have any effect at all. Anyway... another potential 'flavor' of Coffee Leaf Rust.