An innovative cheap filtration system to improve the conservation of extra virgin olive oil

The Extra Virgin Olive is characterized by high quality both from nutraceutical and from sensory point of view. This high quality depends on various factors: the seasonal pedoclimatic conditions, the ripening stage and the health status of the olives, the storage time before crushing of the olives, the conditions of crushing, malaxation and separation of the oil. In order to provide the consumer an high quality extra virgin olive oil, this high quality should be maintained as long as possible. For this purpose, it's crucial a good and immediate filtration of the oil leaving the decanter. In this work we propose a new filtration system consisting of a steel filter and a conventional filter press. The steel filter is made from three bells containing cartridges with decreasing porosity (from 40 µm to 5 µm). The oil which leaves the last cartridge is dehydrated by final cardboards into the filter press. Furthermore, the filtration system may be provided with a device for removing dissolved oxygen using the technique of stripping at the end of the process. By the comparison of the analyses of filtered and non filtered oils, we can assess some differences: during the storage time of the oil, into the non filtered oil the acidity increases more than in the filtered one. Regarding the phenolic components, the secoiridoidic fraction of the non filtered oil undergoes a process of degradation which wasn't observed for the filtered oil. Even the volatile fraction is preserved by the filtration system, resulting more abundant for the filtered oils. From a sensory point of view, even though stored in conditions of high oxidative stress, the oils filtered with the new filtration system were free from defects for many months, while the non filtered oils were already defective after two months, mainly due to defect from fermentative origin. Another important advantage of the new filtration system is due to the possibility to drastically reduce the costs of the filtration process: the first stage of filtration in the steel filter allows to increase the lifetime of the filter in carton. As a consequence, we can reduce the number of cartons, the oil leaks and the cost of disposal of the cartons.