Several scientific works have highlighted that the phenolic fraction develops an important role in the conservation and, therefore, in the shelf-life of virgin olive oil (VOO). In this paper a temperature decreasing (-18\ub0C) of the raw material was evaluated by determining its effect on the phenolic compounds and on the oxidative stability of the derived VOO.
A comparison between oil samples obtained from freezed olives (24 hours at -18\ub0C), crushed with (FS) and without (TOS) thawing out and compared with a control sample (CS) was carried out.
The oxidative stability was studied by the peroxide value, a measure of the primary oxidative products, and the OSI (Oxidative Stability Instrument) time value, a measure of the secondary products, extrapolating (in hours) the end of induction period of oxidative process. The phenolic content was determined by both a spectrophotometric assay (Total Phenol, TP) and a high-performance liquid chromatographic method, by UV and mass spectrometric detection (HPLC-DAD-MSD). This latter allowed to quantify several single phenolic compounds, belonging to phenyl ethyl alcohols, lignans and secoiridoids, and the main o-diphenolic components, which are molecules provided with the highest antiradical power.
The effect of olives pre-treatment was different for the two thesis considered (FS and TOS). Sample FS showed similar oxidative stability and the same phenolic activity and content with respect to the CS. On the contrary, sample TOS showed lower values of the same parameters
