Quantitative Water Content Measurements in Food Wafers Using Terahertz Radiation

A quantitative, non-invasive method of measuring the moisture content (< 25 wt %) of solid food wafers is presented. The method utilizes terahertz (THz) radiation and exploits its high sensitivity to small amounts of water. A linear relationship between transmitted THz signal intensity and moisture content is observed in the range 0.2-0.6 THz. Higher frequencies are affected by scattering due to the size of the pores in the food wafer. A robust quantitative measurement protocol, which requires simple calibration, is implemented based on a direct interpretation of the THz time domain signal.