Effect of Long-Term Storage Temperature on the Quality of Extra-Virgin Olive Oil (Coratina cv.): A Multivariate Discriminant Approach

Kinetic evolution of quality parameters in 21 extra-virgin olive oils (EVOOs) from Coratina cultivar was evaluated during 18 months of dark storage at room temperature (RT) and 4 °C (LT). The aim was to identify the most discriminating variables—fatty acids, peroxide value, spectrophotometric indices, and phenolic compounds—using kinetic analysis and multivariate statistics. Fatty acids remained stable, while peroxide value and ultraviolet absorbance indices increased significantly at RT, following zero-order kinetics. Polyphenols declined markedly after 6 months, especially at RT, with degradation rates influenced by initial concentrations. Hydroxytyrosol and tyrosol followed pseudo-zero-order kinetics, whereas secoiridoids and lignans followed second-order kinetics. Discriminant analysis achieved 90% accuracy (p = 0.000012) in classifying oils by storage condition. The most relevant discriminants were associated with phenolic degradation and oxidative changes. These findings support the importance of low-temperature storage in preserving the biochemical quality and shelf life of EVOOs.