This research work was conducted to establish whether monovarietal olive oils could be differentiated by their basic classes of compounds, ie (a) fatty acids, (b) fatty alcohols, (c) polycyclic triterpenes and (d) squalene. The ratio values of biosynthetically correlated acids were also examined. The mentioned classes of compounds, formed in distinct biosynthetic compartments of the olive fruit, should represent characteristic compositional data of an olive cultivar. The widely cultivated Italian olive cultivars studied were Frantoio, Bosana, Dritta and Leccino. Principal component analysis (PCA) was applied to the analytical data to reveal the compounds (variables) with the highest weights (loadings), with the aim of using them in subsequent computations. These variables were tetracosanol, hexacosanol 5 -avenasterol, cycloartenol, 24-methylencycloartenol, oleic, linoleic, linolenic, stearic and palmitoleic acids and the ratios palmitic/stearic, palmitic/palmitoleic and linoleic/linolenic. Linear discriminant analysis (LDA), carried out on a training set of 57 oils (13 Dritta, 25 Leccino, 12 Frantoio and seven Bosana) produced a 96% correct group classification. The prediction LDA model created with the training set was validated with a test set of 19 oil samples (six Dritta, seven Leccino, four Frantoio and two Bosana), permitting accurate classification of all the 'unknown' olive oils.

When Principal Components Analysis (PCA) was applied to the whole set of data consisting of alcohols, triterpenes and acids, the PCA revealed that the compounds (variables) that gave the better class distinction were: cycloartenol for Coratina, acids C20:0, C17:0, C18:0 for Dritta, citrostadienol for Frantoio and β-sitosterol for Moraiolo. Bosana and Provenzale correlated with erythrodiol and uvaol. A correct assignment of each oil sample to its monovarietal group was obtained.

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The quality of monovarietal extra virgin olive oil from cv. 'Taggiasca' is infl uenced by many factors that have impact on shelf-life as well as on sensory and healthy properties of the product. The aim of the work was to recreate the conditions similar to those in consumer sales point (conditions of "shelf"), maintaining the olive oil packaged in dark-green bottles at room temperature (between 18 and 25 °C) under artifi cial light and away from heat sources, monitoring the oils up to 12 months from bottling with quarterly sampling for the main chemical, physico-chemical, and sensory parameters related to the quality. After one year of storage, an organoleptic alteration with reduction of the attributes 'fruity', 'pungent', and 'bitter', as well as the occurrence of 'rancid' defect, was observed. This alteration was found to be accompanied by a decrease in phenolic substances and tocopherols and an increase in primary and secondary oxidation products. The composition of the volatile fraction showed a slight increase of substances related to rancid defect, a constant trend of compounds related to fruitiness, and a slight decrease in alcohols. It can be concluded that the optimum time of storage of the oil under the above-mentioned conditions is approximately 9 months.