Detecting Olive Oil Fraud with Near-Infrared Spectroscopy and Chemometrics: A Modern Safety Control Approach

Background: Olive oil is one of the most essential components of the Mediterranean diet, obtained by mechanical extraction from the Olea europaea tree. Based on organoleptic properties (odor and taste) and the amount of free fatty acids, it is divided into three categories: olive oil, virgin olive oil, and extra virgin olive oil. Due to the expensive production procedure of extra virgin olive oil, it is prone to adulteration with low-quality olive oils and other vegetable oils. Objectives: The current study focused on determining the authenticity of olive oil using near-infrared spectroscopy as a non-destructive method in conjunction with chemometrics. Methods: In this study, 100 samples of olive oils, comprising 34 domestic and 66 industrial olive oils, were purchased from the markets of Tehran and Roudbar. Common adulterants such as corn, canola, sunflower, and soybean oils were considered. Binary and ternary mixtures of olive oil with these vegetable oils were prepared and analyzed. Spectra were collected over the range of 12000 cm-1 to 4000 cm-1, and the data were preprocessed using SNV and Detrend before principal component analysis (PCA). Results: The results indicated that corn oil and canola oil were the dominant adulterants in the olive oil samples, likely due to their inexpensiveness and availability in Iran. Conclusions: Since multiple types of fraud were identified in the examined samples, it is recommended that future studies investigate other forms of fraud simultaneously. Additionally, the results demonstrated that principal component analysis could effectively categorize different samples with acceptable discrimination.