Qualitative analysis of edible oil mixture for omega-3 content using terahertz time-domain spectroscopy

The utility of terahertz time-domain spectroscopy (THz-TDS) for the qualitative and quantitative analysis of edible oils remains underexplored. Therefore, we aimed to characterize an edible oil mixture consisting of perilla, soybean, and corn oils using THz-TDS spectroscopy and compare the findings with those from Fourier transform infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance (1H NMR) spectroscopy. THz-TDS was used to obtain complex optical constants such as power absorption and refractive index of oils in the range of 0.2–2.0 THz. Perilla oil mixtures were quantitatively analyzed using complex dielectric constants in the THz frequency region. We characterized the double bond structure of omega-3 in perilla oil using THz-TDS. Furthermore, we used reflection-mode THz-TDS imaging to demonstrate its application as a non-destructive authenticity test for bottled edible oil.