## 3 Results and Discussion
### Physicochemical Parameters
#### 3.1.3 Extinction Coefficients K\({}_{232}\) y K\({}_{268}\)  
In the results shown in Table 5 for A, there was an increase in the mean K\({}_{232}\) values for O04 and O1 at T3 treatment, with increases of 13.64% and 13.08%, respectively. This trend in the K\({}_{232}\) coefficient showed the following disparate changes at 60 \({}^{\circ}\)C: an increase in O1 and a decrease in O04. This could be explained by the higher concentration of virgin olive oil in O1 compared to O04, causing the primary oxidation compounds to continue increasing in the former and transforming into secondary compounds in the latter [33]. Regarding K\({}_{268}\), the values remained slightly higher than the control and stable with the treatments. These increases are due to the formation of oxidation products that explain the decrease in PV [43; 44]. In B, O04 showed a slight increase compared to O1 in the most severe treatments for K\({}_{232}\), while O04 obtained higher results in all treatments than O1 for K\({}_{268}\). There was no constant trend of increasing or decreasing values after applying the treatments. However, at 60 \({}^{\circ}\)C in O04 and O1, there was an increase in the mean values between the control sample and the most extreme treatment for K\({}_{268}\) of 16.28% and 51.22%, with values of 0.65-0.75 and 0.41-0.62, respectively. Additionally, there was an increase in the mean values for K\({}_{232}\) in O04 at T12 treatment, with values higher than 20%, ranging from 2.91 to 3.18 compared to the control value (2.39). This explains the increase in the K\({}_{232}\) coefficient after thermal application to the samples as determined by other authors [37; 44].  
In K\({}_{268}\), both olive oils showed a notable increase after thermal treatment and one year of storage (Experiment B). This seems to indicate that prolonged storage produced the transformation of primary oxidation compounds, which were still present in the thermally treated and yet-to-be-stored oils, into secondary oxidation compounds related to this coefficient after the storage period [33]. This can be correlated with the decrease in the peroxide value (PV) in some cases. As observed by other authors, the increase in extreme conditions produced a decrease in primary oxidation compounds (PV) and an increase in secondary oxidation compounds (K\({}_{268}\)) [33]. This may be due to the intrinsic properties of each type of oil, which allow them to transfer greater or lesser stability to the treatments.  
The K\({}_{232}\) and K\({}_{268}\) extinction coefficients are critical indicators of the oxidation levels in oils, with K\({}_{232}\) reflecting the concentration of primary oxidation products and K\({}_{268}\) indicating secondary oxidation products. These coefficients are directly related to the oil's quality and stability, and their changes can provide insights into the effects of PET degradation and thermal treatments on the oil [37]. Regarding compliance with legislation, the K\({}_{232}\) coefficient is not regulated for olive oils, while K\({}_{268}\) has a limit value of \(\leq\)0.90 [24,30]. Therefore, the effect of the treatments on both oils did not exceed this limit.