There were two big debates on this trip and one of them centered around reposa, the resting period where coffee is off the patio but still in parchment. This is a way to let water content stabilize and in theory, to get a more homogeneous product. Reposa often happens in a place with a balance of temperature and air flow that will allow the green to settle but not promote mold growth.
The debate for me came from the materials used in reposa. I often have a big problem with jute. Jute bags are the scourge of great coffees everywhere and yet there are few alternatives that aren't much more expensive. One common exchange is the plastic feedbag that is used for agricultural products and comes much cheaper than jute. The problem is that it does not 'breathe' freely and molds will grow so it is never used in transport.
This presents an interesting balance as a coffee in reposa will homogenize better if stored in jute but risks some contamination during this critical stage. If the sterile feed bags are used, there is the real risk that the coffee may have increased mold growth. The jute quality seems to play greatly into this as the thicker and better quality the bag, the more the flavors seem to seep in. A pristine coffee could quickly develop nutty hazelnut flavors that in time will become the hallmark of baggy notes. You probably won't pick it out in a darker roast but with the right profile, you will.
The best project we undertook was to get some green coffee last year at Finca Vista Hermosa and vacuum seal it. I then returned with the green coffees and kept them stored in both frozen and room temp situations. Having this coffee taken straight from reposa and sample milled gave a stark contrast to other coffees from FVH that had made the travel from origin via ship and packed in jute.
We recently roasted a sample of the jute coffee vs the vacuum sample with an almost identical profile through first and in the drop. The results were staggering. A fresh clean note and sweet acidity on the vacuum sealed coffee and a spice snappy unpleasant acidity on the jute coffee. At close to a year from harvest, this presents a unique comparison.
The quick summary of what we learned this trip was that coffees stored in plastic during reposa are a risk for one problem while in jute another. It's possible that drying racks of either metal or wood with liners should be considered for progressive farms to use at this stage. The other item reconfirmed what we already knew, coffees deteriorate and fall apart as they age and jute is a big contaminant. Aroma first, acidity, and then finally sweetness goes all the while the bag flavors increase.
At some point, we are going to have to see if reposa can be done in a vac sealed bag on the way to Cambridge.