Chemical evaluation and thermal behavior of Chilean hazelnut oil ( Gevuina avellana Mol) a comparative study with extra virgin olive oil

There is a growing interest in the study of oils from native fruits, especially when the oil has high quality. In this sense it is mandatory to evaluate the oxidative stability and the relationship with the modifications of the fatty acid content, physicochemical parameters, the antioxidant capacity and its protection against the thermal deterioration processes. The fatty acid profiles of Chilean hazelnut oil showed a relevant presence of the omega series (ω-9, ω-5, and ω-9) with good stability across the thermal treatment. The physico–chemical parameters such as polar compounds and absorption coefficients K232 and K270 showed a similar behavior compared with olive oil oxidation in the range of 25–360 °C. The antioxidant capacity and total phenolic content in olive oil is significatively higher than Chilean hazelnut oil at 25 °C; however, this antioxidant capacity decreases in the olive oil after 100 °C; until 247 °C the antioxidant capacities for both oils are equalized. Total phenolic content of olive oil diminishes after 100 °C until the final study temperature (360 °C), where its concentration is very similar to Chilean hazelnut oil. The results of the thermogravimetric and differential analysis in the range of 100–700 °C show that the thermal oxidative decomposition processes occurred in both samples mainly in three steps with a total mass loss for olive oil and Chilean hazelnut oil of 99.7% and 99.9%, respectively. It is important to note that hazelnut oil remains thermally stable up to 247 °C just a few degrees lower than olive oil (252 °C).