Development of an ESP32 Microcontroller-based Colorimeter with an Android App for the Verification of Roasting Degree of Coffee Beans

A lo w-cost and portable colorimeter was developed using an ESP32 microcontroller and a TCS34725 color sensor to monitor the degree of coffee roast, crucial for maintaining flavor consistency and controlling product quality across different batches. The colorimeter detected color recognition resulting in RGB color intensity values, which could be displayed on the device’s TFT LCD touchscreen. Additionally, colorimetric data was transmitted in real-time via WiFi and stored in a MySQL database using an Android app created with the MIT App Inventor platform. The colorimeter was powered by a rechargeable lithium phosphate battery. The consistency of coffee roasting was ensured by self-identifying the standard RGB values of the roasted coffee beans at five degrees (light, light-medium, medium, medium-dark, and dark) with the app. The darker the color of the roasted coffee, the lower the RGB values were gained. The color detection was highly precise, with a relative standard deviation of less than 5%.