Factors affecting olive oil quality
Olive (Olea europaea, Z.), an evergreen tree has been cultivated for thousands years, in many semi-arid and arid mountainous areas surrounding the Mediterranean Sea. Olive oil is extracted from the olive fruit by mechanical means, without any chemical treatment thus preserving all of its natural constituents, which are responsible for the unique flavor, as appreciated by consumers. This thesis concentrates on the important factors that might affect the quality of olive oil. These comprise: cultivar / agricultural methods / weather / processing / storage. Of the quantitative and qualitative results obtained, the following are of particular interest. The olive variety influenced the chemical composition and sensory quality of the olive oil. Particularly affected were the composition of fatty acids, sterols, aliphatic and triterpene alcohols, phenolic compounds and sensory attributes. Osmotic stress, due to no irrigation or to saline irrigation, influenced the size and oil content of the fruit and the composition of triacylglycerol molecular species, fatty acids, total phenols, secoiridoid derivatives as well as volatile compounds and sensory attributes of olive oil The processing methods affected the sensory quality and the phenolic compounds of olive oil. The most significant variations occured mainly due to the quantity of water added to the system of extraction and the duration and temperature of malaxation. The alteration of these during the extraction process was reflected in oxidative processes. The rate of olive oil oxidation was a function of both the time and the various conditions of storage. Virgin olive oil keeps its qualitative characteristics under the category of extra virgin olive oil for 15 months if it is stored in tin containers indoors at room temperature and with nitrogen in the headspace. The present studies provide information for the olive oil industry in order to improve the overall olive oil quality by optimising each step of the production chain.