## 4 Discussion
### Effects of Treatments on the Quality of Olive Oil over a 12-Month Storage Period  
Peroxide value, free acidity, and ultraviolet absorbance indices (K232 and K270) increased significantly after 12 months of storage. These results are consistent with the findings of [PERSON] [75], who observed notable increases in peroxide values after 7 months, particularly in oils stored at room temperature compared to those under refrigeration. The rise in free acidity is primarily attributed to the hydrolysis of triglycerides, which leads to the release of free fatty acids. This reaction is accelerated by oxygen exposure, even in the absence of light, as shown in the samples stored in half-filled test tubes with air headspace at room temperature for 6 and 12 months, which are conditions that mimic typical household storage. Oxygen promotes both oxidative and enzymatic degradation, contributing to overall quality deterioration, resulting in increases of oil acidity as reported by others too [76; 77]. Additionally, the progressive degradation of phenolic compounds during storage weakens the oil's antioxidant defense system, further accelerating oxidation and increasing acidity [78]. [PERSON] et al. [79] found that oils stored in partially filled containers--similar to the conditions in the present trial--showed a sharp rise in peroxide values after 12 months, underscoring the importance of minimizing oxygen exposure. Recent studies reinforce these observations and emphasize the critical role of oxygen in olive oil degradation. [PERSON] and [PERSON] [80] reported that air exposure significantly increased peroxide values and free acidity. Similarly, [PERSON] et al. [78] and [PERSON] [81] found that oxygen exposure during storage accelerated oxidation, as indicated by higher K232 and K270 values, and contributed to phenolic degradation. [PERSON] et al. [82] also confirmed that oxidative markers increased with both storage duration and oxygen contact. These results corroborate the findings of the present study. The concentration of total polyphenols and the antioxidant capacity of the olive oil showed a marked decrease during storage. These results align with [PERSON] [75], who reported up to a 70% reduction in total phenolic content over time. A detailed analysis of individual phenolics revealed increases in hydroxytyrosol and tyrosol concentrations, while other phenolic compounds declined. This shift suggests that storage not only reduces overall phenolic content, but it also alters the qualitative composition of the phenolic profile. [PERSON] et al. [13] similarly showed that changes in phenolic compounds during storage are closely linked to the peroxide value. Specifically, when peroxide values remained below the acceptable threshold (20 meq O\({}_{2}\)/kg olive oil), a significant portion of hydroxytyrosol and tyrosol derivatives persisted. These findings highlight the scavenging role of phenolic compounds and their interaction with peroxide formation in shaping the phenolic profile. Moreover, phenolic degradation during storage--even in the absence of light--is strongly influenced by key factors such as the degree of fatty acid unsaturation, the volume of headspace oxygen, and ambient temperature. These variables directly affect hydroperoxide formation, which in turn accelerates phenolic oxidation and contributes to the overall decline in oil quality [13]. The reduction of antioxidant compounds, particularly phenolics, was expected, given their central role in maintaining oxidative stability. These compounds protect fatty acids from oxidative degradation and help prevent deterioration of the oil through both oxidative and hydrolytic reactions [60]. Among the treatments examined, the CD treatment exhibited the highest rate of degradation in total phenols, o-diphenyl, flavonoids, and antioxidant capacity (as measured by FRAP) as indicated by the significant differences in the corresponding regression lines.