To honor the meticulous work done at the wet mill (the 15-18h dry ferment and 33h soak), the roasting profile must be “protective.” Your goal is to develop the amino acids into complex sugars without reaching the temperatures where Chlorogenic Acids (CGAs) degrade into bitter quinic acid.
Here is the strategic roasting framework for this specific specialty process:

  1. The Roasting Phase Strategy
    Phase A: The Drying Phase (The “Gentle Start”)
    Because of the 33-hour soak, these beans have high internal turgor pressure and a very uniform moisture distribution.
  • Strategy: Start with a moderate charge temperature. If you “shock” the bean with too much heat early, you risk case hardening, which traps moisture inside and leads to a “metallic” phenolic taste.
  • Goal: Slow, even heat penetration to prepare the amino acids for the next stage.
    Phase B: The Maillard Zone (The “Amino Acid Development”)
    This is where your 33-hour soak pays off. This phase (from 150°C to First Crack) is where amino acids and sugars react.
  • Strategy: Extend this phase slightly.
  • Why: Since you have a higher concentration of free amino acids from the soak, a longer Maillard phase allows for the development of that deep, savory-sweet complexity (toffee/malt) that balances the phosphoric acidity.
    Phase C: Development Time (The “Phosphoric Protector”)
  • Strategy: Keep Development Time Ratio (DTR) between 12% and 15%.
  • Why: Phosphoric acid is delicate. If you push the roast too far or too long after First Crack, the acidity will “flatten” and turn into simple carbon bitterness. You want to drop the coffee just as the acidity peaks—usually at a light-medium (City) roast level.
  1. Recommended Roasting Targets
    Profile Stage Temperature Range Strategy
    Charge Temp 190°C – 205°C Moderate; avoid scorching the outer cellulose.
    Drying Time 4:30 – 5:30 mins Ensure the core is heated before the exterior browns.
    Maillard Time 3:30 – 4:30 mins Maximize this for savory-sweet amino notes.
    First Crack ~196°C Listen for a “crisp” crack (indicates high density).
    Development 1:15 – 1:45 mins Short/Fast to preserve Phosphoric sparkle.
    End Temp 208°C – 212°C Drop early to keep the CGA/Clean Cup profile. Troubleshooting the Sensory Connection
    • If you taste “Ash/Smoke”: You are roasting too hot/too fast. The CGAs are breaking down into phenols. Lower your charge temperature.
    • If you taste “Bread/Grain”: The drying phase was too long. You’ve stalled the sugars. Increase early heat.
    • If you taste “Vinegar/Sharpness”: This is likely a mill error (over-fermentation), but you can mask it by slightly extending the Maillard phase to add more sweetness.
    Pro Tip: Because “double-washed” Kenyan-style coffee is so dense, it can handle a higher heat application in the middle of the roast (Maillard) than a natural process could. Use this to build “structure” in the cup.The Final Correlation Loop
    • Wet Mill: 18h Dry / 33h Soak (Builds the chemical precursors).
    • Drying Bed: 11.5% Moisture (Stabilizes the precursors).
    • Roaster: Protective Maillard (Unlocks the precursors).
      Would you like me to summarize this entire “Farm-to-Cup” protocol into a 1-page Executive Summary for your production manager?