Use of nitrogen to improve stability of virgin olive oil during storage

Experiments were carried out to study the possibility of improving the stability of extra virgin olive oil by using nitrogen as a conditioner gas during storage. With this aim, virgin olive oil samples, obtained from Leccino and Coratina cultivars, were stored in the dark, in closed bottles conditioned with air or nitrogen at 12-20 and 40degreesC. Results indicated that the FFA percentage increased over 1% only when oils were stored at 40degreesC. The PV and the K-232 value (light absorbance at 232 nm) of oils increased over the limit value allowed by European Union law when the bottles were only partly filled and air was the conditioner gas. The use of nitrogen as conditioner gas helped to avoid this risk during 24 mon of storage at 12-20degreesC. The total phenolic content of both cultivars oils decreased during storage because their oxidation protected the oils from autoxidation. The content of total volatile compounds in oils decreased continuously during storage at 12-20degreesC, whereas it increased over 10 (Coratina cv.) and 15 (Leccino cv.) mon and then diminished when the storage temperature was 40degreesC. The same behavior, i.e., increase then decrease, was ascertained for trans-2-hexenal. The hexanal content of oils increased continuously during storage because this compound is formed by the decomposition of the 13-hydroperoxide of linoleic acid.