Maximizing Coffee Washing Station Profits: Results from Field Experiments

TechnoServe shares research and guidelines for improving coffee cup quality and wet mill profitability.

Cup quality is the primary factor determining both a coffee’s market value and the income farmers receive. While it is widely recognized that agronomic practices, pulper calibration, cherry ripeness, and fermentation techniques all shape cup quality, there has been relatively little effort to systematically measure their impact.

To close this gap, TechnoServe has conducted a series of studies in East Africa examining how different practices influence cup quality. These insights are helping wet mills, cooperatives, agronomists, and other actors in the coffee value chain adopt practices that can raise quality—and, in turn, farmer incomes.

• Presentation: Maximizing Coffee Washing Station Profits

Field Experiment Reports

• Fermentation Experiment Report: Studying the effect of fermentation type on cup scores and overall time to completion with the hopes of identifying a fermentation type that reduces costs and promotes cup quality
  • Summary of Fermentation Experiment
• Cherry Ripeness Experiment Report: Investigating the impact of coffee cherry delivery composition on cup quality
  • Summary of Experiment on Cherry Ripeness and Cup Quality
  • Summary of Economic Analysis of Processing Defects
• Eco-Pulper Processing Experiment Report: A 2010 study comparing cup quality and water usage between traditional disc pulpers and eco-pulpers.
• Impact of Stumping Coffea arabica Trees on the Physical and Sensorial Attributes of Resulting Coffee Samples: A 2024/2025 field experiment from Ethiopia highlighting the impact of coffee rejuvenation.

Wet Mill Resources

• Coffee Wet Mill Processing Guide: A comprehensive resource to provide wet mill managers in East Africa with guidelines on preserving Arabica coffee bean quality during wet mill processing
• Android Apps for Wet Mills: TechnoServe has developed a suite of tools to improve the profitability, sustainability, and transparency of wet mill operations:
  • Cherie – Coffee Cherry Quality: Uses a machine learning algorithm to assess the mix of ripe, unripe, and overripe coffee cherries
  • TerraTrac: App for crop traceability for compliance with EU deforestation regulation
  • CoopTrac: A tool used to evaluate cooperative health
  • CPQI – Coffee Processing and Quality Index: Encompasses a variety of questions tailored to facilitate daily CPQI audits

Resources from Other Organizations

• SPREAD 2008 Eco-Process Research Report: A study published from the National University of Rwanda evaluating the effect of pulping machine type and wet processing system on the cost of production and quality of specialty coffee in Rwanda