# Coffee Bean Characterization Using Terahertz Sensing

## TL;DR

A new method for sorting coffee beans using terahertz sensing is introduced, which can detect internal moisture levels to improve roasting efficiency.

## Contribution

A novel THz-based sorting method is developed that can assess internal bean properties for industrial automation.

## Key findings

- THz spectroscopy can penetrate green and roasted coffee beans to detect internal moisture.
- A robot-guided THz system was implemented for automated bean scanning and sorting.
- THz technology shows potential for moisture analysis in various industrial applications.

## Abstract

Coffee bean sorting is currently based primarily on visual appearance and near-infrared techniques that probe the bean’s skin. However, sorting based on compositional differences has significant potential to optimize the roasting process. We present a novel coffee bean sorting method using terahertz (THz) spectroscopy, which effectively penetrates both green and roasted beans. Our findings show that the optical properties of coffee beans at THz frequencies are primarily governed by internal moisture levels. To demonstrate industrial feasibility, we implement a robot-guided THz sensing system capable of scanning beds of beans for automated sorting. More broadly, our results confirm the potential of THz technology for moisture content analysis across various applications.