New Project Aims To Improve Post-Harvest Coffee Processing – CoffeeTalk

A new project is focusing on improving post-harvest coffee processing by addressing the issue of inconsistent quality and post-harvest losses due to the lack of affordable technology for monitoring and controlling fermentation and drying processes. Over 125 million people globally depend on coffee, with the majority being smallholder farmers in low-income, climate-vulnerable regions. Without real-time data, farmers rely on guesswork, leading to under- or over-fermentation, mold growth, or uneven drying, resulting in spoilage rates of up to 20% and downgraded quality. In Indonesia, where smallholder farmers produce over 90% of the country’s coffee, many operate without standardized post-harvest practices or equipment, contributing to inconsistent bean quality, price volatility, and limited market access.

The solution targets these issues by enabling real-time monitoring of key variables during post-harvest processing using low-cost IoT sensors and a cloud-based platform. This empowers farmers with data-driven tools to improve quality, reduce waste, and adapt to changing climate conditions. As climate change threatens to reduce coffee-suitable land by up to 50% by 2050, improving post-harvest efficiency is essential to sustaining livelihoods and ensuring a more climate-resilient, low-carbon food system.

The Nordic Semiconductor nRF54L15 DK is a system designed to monitor environmental conditions in real-time and communicate results wirelessly using the advanced features of the ESP32 platform. The system consists of three key sensing components and two microcontroller units: the DHT22 Temperature Sensor and DFRobot Analog pH Sensor. The ESP32 Controller serves as the data acquisition unit, while the nRF54L15 DK Controller acts as the central communication and control unit. The system works in four steps: data acquisition via ESP32, serial communication, and data handling by the nRF54L15 DK. The data can be displayed on an LCD or OLED screen, stored locally on SD or EEPROM, transmitted via Bluetooth Low Energy (BLE), or uploaded to the cloud for remote monitoring. The nRF54L15 DK collects, controls, and monitors temperature, time, and pH during the fermentation process to reduce the risk of sour or off flavors, bacterial growth, and insect invasion.

The experiment involved coffee beans stored in a refrigerator for 2 months and tested in an open loop fermentation temperature control process using an IoT-based system. The experiment aimed to determine the change in pH rate with various temperature variations in the fermentation medium. The coffee beans did not experience acid formation, but the pH value can only change when the temperature is controlled. The temperature was controlled below the ambient temperature for 0 to 200 minutes, causing a decrease in pH from 7.4 to 7.2. The temperature was then controlled at a temperature close to the ambient temperature for approximately 6.6 hours, causing a decrease in pH. The controlled cooling process at 20°C caused an increase in pH, while the controlled heating process at 50°C caused a decrease. The system simplifies data access through a mobile dashboard with visual alerts and multilingual, low-literacy-friendly interfaces, empowering users to standardize post-harvest practices, improve quality, and reduce guesswork. This flexibility enables farmers to better adapt to shifting market demands and contributes to a more sustainable, climate-resilient coffee economy.

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