Rapid detection of virgin olive oil adulteration via chemometric analysis of raw differential scanning calorimetry data and pretreated fourier transform infrared spectroscopy
Onur Özdikicierler, Tolga Akcan, Pelin Günç Ergönül, Ebru KARACAN
Abstract
Abstract This study demonstrated that both untreated Differential Scanning Calorimetry (DSC) data and pretreated Fourier Transform Infrared (FTIR) spectra can effectively detect low-level adulteration of virgin olive oil (VOO) with sunflower oil, palm olein, and cottonseed oil using chemometric methods. The peaks and features in the FTIR and DSC results of the adulterated samples were associated with variations in fatty acid and triglyceride composition. The melting behaviors of the highly unsaturated and saturated triglycerides were the primary factors for the differences observed in the heating thermograms of VOO and other vegetable oils. Results revealed that the FTIR fingerprint region (1500–650 cm⁻¹) provided the most accurate predictions, achieving an R 2 of 0.97 and an RMSEC of 0.18 using Partial Least Squares (PLS) regression. In comparison, DSC analysis, despite no data pretreatment, yielded a strong R 2 of 0.93 and an RMSEC of 0.27. Critical indicators of adulteration in DSC thermograms included maximum and total signal changes between − 4 °C and − 18 °C, the onset of exothermic peaks between − 32 °C and − 54 °C during cooling, and enthalpy variations in the heating profile. These results highlight the potential of both FTIR and DSC—particularly DSC’s unpretreated thermograms—as rapid, reliable tools for detecting VOO adulteration.