Attenuated total reflectance terahertz spectroscopy for quantitative measurement of somatic cell count in bovine milk

Quantitative somatic cell count (SCC) measurement for detection of mastitis using an attenuated total reflectance (ATR) terahertz (THz) spectroscopy was investigated. Using samples with controlled SCC derived from raw milk, we measured their ATR signal in the THz region 30-440 cm−1 with a Fourier-Transform THz spectrometer. We found ATR signals decreased as SCC increased. Furthermore, we found the correlation between the ATR signal and SCC from 8.0 × 104 to 1.57 × 106 cells/mL was optimal at 139 cm−1 (R2 = 098). These findings demonstrate a potential to detect mastitis with a monochromatic THz wave.