The freezing process helps to preserve the quality of extra virgin olive oil over time: A case study up to 18 months

The effects of a long storage period on some Tuscan EVOOs filtered and frozen at - 23 °C in comparison with the same specimens maintained at room temperature in the dark, were evaluated by monitoring the evolution of their phenolic composition and aromatic profile.The oils were analyzed immediately after opening and after 10 days up to 18 months after oil bottling. A non parametric statistical analysis and principal components analysis (PCA) coupled to linear discriminant analysis (LDA) was applied for assessing the differences among the trials. Increments in tyrosol, hydroxytyrosol and % of hydrolysis were observed for EVOOs stored at room temperatures starting from 3-months storage, and increased thereafter. The frozen EVOOs were statistically undistinguishable over time, differently from the correspondent ones at room temperature. All the frozen EVOOs showed negligible differences in aromatic profile until 12 month of storage. Some compounds potentially related to off-odor sensations were significantly increased in the unfrozen specimens only at 18 months.