Identification of camellia oil adulteration by using near infrared spectroscopy combined with two dimensional correlation spectroscopy (2DCOS) analysis

Camellia oil (CAO), a unique edible plant oil native to China with distinct nutritional benefits, is often adulterated with cheaper oils due to its high profit. Therefore, the detection of the types and concentrations of these adulterants is crucial. In this study, the near-infrared (NIR) spectroscopy combined with two dimensional correlation spectroscopy (2DCOS) analysis method is proposed, revealing the interaction mechanism of adulterants in CAO, while enabling the rapid identification and quantification of adulteration in CAO. Firstly, Adulterated CAO samples with different concentration gradients were prepared, and the spectral characterization of the oil samples was completed. Then, the 2DCOS method was applied to distinguish highly overlapping spectral bands in adulterated oils of different concentrations. Synchronous spectra were employed to identify characteristic wavelengths from autocorrelation peaks, and asynchronous spectra were employed to analyze the sequential interaction of fatty acid fusion in adulterated oils under varying concentration gradients. Furthermore, the simplified multispectral models using support vector machine (SVM) and Partial Least Squares Regression (PLSR) were established with selected characteristic wavelengths as input variables. The established multispectral models demonstrated good performance with an accuracy of 92.78 %, the determination coefficients between 0.9601 and 0.9940, and the limits of detection between 0.70 % and 1.84 % for these adulterated oils. These results indicate that NIR spectroscopy combined with 2DCOS can be used to serve as a powerful rapid detection technique for adulteration analysis in CAO, and provides new methods for the interaction mechanism of adulterated oil components.