The evolution of the extra virgin in the bottle. Better glass, PVC or Pet?
Air, light and oxygen are the enemies of olive oil. The package can mitigate the degradation in natural reason of various factors, not only for the material
What is the best box for the extra virgin olive oil is to preserve the best and the most long as possible to the potential customer?
Most of the scientific studies concern the preservations in tanks and vats, rarely taking into account the packaging in which the oil is on the market.
Some research in this direction, however, exist.
The main factors that influence the oxidation (ie light, oxygen permeability of the packaging materials and storage temperature), were combined in several cases of study considering various storage materials.
The more pronounced effect of temperature in the degradation of the product there is certainly in the Pet and PVC, but is less pronounced in the case of the glass. However, the plastic containers have shown a protective role very high when the oil was exposed to light.
But what is the average life of a standard quality oil stored in different containers? When the chemical parameters (acidity, peroxides, spectrophotometry) no longer complies with the commercial category of extra virgin?
May be 6 months when packaged in clear glass but kept in the dark at temperatures up to 22 ° C; 3 months in Pet transparent stored in the dark at 22 ° C and less than 3 months in transparent PVC stored in the dark at 22 ° C.
When exposed to light, the shelf life of olive oil was 9 months when packed in Pet covered with aluminum foil; 3 months packaged in Pet covered with a UV filter and less than 3 months in Pet transparent . In all cases shown, the storage temperature was 22 ° C.
Beyond a certain threshold temperature (35 ° C) storage is however less than three months, irrespective of the material used.
The shelf life of an oil, however, depends heavily by the substance contained or by the characteristics of the oil to start. In the case of a storage for 21 months at room temperature in the dark and the reduction of total phenolic compounds ranged from 43% to 73%. Noteworthy is that the decrease was higher in the samples whose initial phenol was greater.
The parameter which, however, proved to be more sensitive was the K232 that, first, exceeded the permissible limits for all oils under test.
But it is not just a question of material or quality of oil to start, or only in light, temperature and oxygen. The decay kinetics of the quality of a virgin olive oil is very dependent on the size of the container. Even the geometry, ie its shape, influence the shelf life because directly correlated with the initial value of the pressure of oxygen in the head space of the bottle.