Evaluating the thermal stability of hazelnut oil in comparison with common edible oils in Turkey using ATR infrared spectroscopy

Abstract

Hazelnut oil (HO), a high-quality nutrient rich in monounsaturated fatty acids and antioxidants, is not commonly used due to a lack of awareness of its nutritional benefits. The purpose of the current study is to evaluate the stability of HO during the heating process in comparison with Riviera olive, sunflower and corn oils, the most commonly used edible oils in Turkey, by using Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR). The oils were heated at 180 °C for 24 h, divided into 8-h periods over the course of three days and the measurements were performed on oil samples taken every 2 h. Thermogravimetric analysis-differential thermal analysis (TGA-DTA) and the measurement of the specific absorbance of conjugated dienes and trienes by using UV–visible spectroscopy were also performed to confirm the ATR-FTIR data. The spectroscopic results showed that the heating process led to an increase in the amount of primary and secondary oxidation products, a decrease in the amount of cis fatty acids and an increase in the amount of trans fatty acids in all oils. Based on the results of linear regression analysis, HO has the lowest slope value for all parameters, indicating that it is the most resistant to thermal oxidation. Principal Component Analysis (PCA), Hierarchical Cluster Analysis (HCA) and TGA-DTA results confirmed that HO has a higher thermal stability than the other oils. These findings revealed that HO has the highest thermal stability among the oils compared and can be utilized as a healthy alternative for cooking. This study also showed that ATR-FTIR spectroscopy holds significant promise in oil analysis, competing with routine quality control techniques.