What is cooking in your kitchen: seeing invisible with time-resolved coherent anti-Stokes Raman spectroscopy

Cooking oil is a critical component of human food and its main component, lipid, is influential to health, but assessing its authenticity and quality can be challenging due to its complex chemical composition. In this study, we introduce a novel application of time-resolved coherent anti-Stokes Raman scattering (T-CARS) spectroscopy for detecting adulteration and understanding the mechanisms of lipid oxidation in various cooking oils. Our research surpasses the limitations of conventional spontaneous Raman spectroscopy, demonstrating that intra-molecular interactions from unsaturated bonds in triglycerides significantly influence vibrational dephasing time. We observed that these dephasing times, although diverse initially, converge to a similar value after heating cycles. Notably, a longer vibrational dephasing of the CH2 symmetric stretching mode was found to correlate with a higher lipid oxidation rate. These findings underscore the potential of T-CARS in identifying and characterizing subtle molecular interactions, offering a transformative approach to understanding molecular dynamics. This research paves the way for broader applications of T-CARS across fields such as chemistry, biomedicine, and material science, marking a significant advancement in the development of innovative analytical techniques.

Automated summary

Researchers used time-resolved coherent anti-Stokes Raman scattering (T-CARS) spectroscopy to detect adulteration in cooking oil and understand the mechanisms of lipid oxidation. By overcoming the limitations of conventional Raman spectroscopy, they found that intra-molecular interactions in triglycerides significantly influence vibrational dephasing time. They observed that although initial dephasing times varied, they converged to a similar value after heating cycles. Notably, longer vibrational dephasing of the CH2 symmetric stretching mode was found to correlate with a higher lipid oxidation rate.