Malaxing temperature affects volatile and phenol composition as well as other analytical features of virgin olive oilThree Italian olive varieties (Caroleo, Leccino and Dritta) were processed by centrifugation in the oil mill. The olive paste was kneaded at 20, 25, 30 and 35°C. The results achieved revealed that the oil content in green volatiles from lipoxygenase pathway (including C 5 and C 6 compounds and especially unsaturated C 6 aldehydes) decreased progressively as the kneading temperature increased, dropping markedly at 35°C. The content of phenols, o-diphenols and secoiridoids showed an opposite trend, but the temperature of 35°C was critical also for them, as it was for the majority of the other components, analytical parameters and indices related to quality, typicality and genuineness. In general, an increasing kneading temperatures increased the release of oil constituents from the vegetable tissue. This factor also affected the oil extraction yields. The best overall results were achieved by malaxing the olive paste at 30°C. In fact, this temperature level led to achieving both pleasant green virgin olive oils and satisfactory oil extraction outputs.

In this study, for the first time, the impact of the genetic factor on the contents of oleuropein in olive leaves was not only evaluated but the influence exerted by the color/age of leaves (green, green-yellowish, and yellow) and the collecting period (spring or autumn) was also evaluated. A repetitive high-resolution gas chromatographic quantitation method and an accurate high-performance liquid chromatographic method were developed. These analytical methods gave results showing a highly linear relationship. Samples of olive leaves were taken from seven major Italian olive cultivars, such as Dritta, Leccino, Caroleo, Coratina, Castiglionese, Nebbio, and Grossa di Cassano. Such a vegetal raw material could actually be exploited for recovering oleuropein, considered to be a high-added value molecule. This could be converted into hydrxytyrosol, a compound known to possess strong bioactive properties. Olive leaves showed considerable contents of oleuropein, which with some cultivars were even higher with respect to those present in the corresponding olive fruits (reported in the literature). The amounts of oleuropein in the collected leaves were markedly modified by the color/age and genetic factors, whereas meaningless variations were ascribable to the quantitation method and the collecting period factors. Various chemometrics, applied to the obtained analytical data, appeared to be effective in discriminating the samples on the basis of the above-examined experimental factors, thus confirming how these should be taken into account in future industrial recovery of oleuropein from olive leaves.

The influence of the olive paste malaxation time on the composition and the industrial output of oil was investigated. To this purpose, three Italian olive varieties (Leccino, Dritta, Caroleo) were processed with a centrifugal system for six malaxation periods (0, 15, 30, 45, 60 and 75 min). The concentrations of the majority of the oil constituents changed during the malaxation. However, these changes were not significant for all of them: the contents of β‐carotene, the major xanthophylls, chlorophylls a and b, pheophytins a and b in the oils increased progressively with increasing malaxing times, whereas the contents of simple and hydrolysable phenols (secoiridoid derivatives), o‐diphenols and total phenols decreased. A significant increase in total volatiles and green volatiles of the lipoxygenase cascade (C6 aldehydes, C6 alcohols, C5 alcohols and C5 carbonyls) was detected. An opposite trend was observed for the green C6 esters. As a result, the global analytical quality, flavour, aroma and shelf‐life of the oils were negatively affected. The oil yield increased substantially up to 45 min of paste malaxation times. Beyond 60 min, the yields tended to decrease.

To gain information about the geographical origin of oil samples, measurements of delta(13)C and delta(18)O of the whole oil and some of its fractions have been performed on samples coming from fruits of Olea europaea L. produced in Greece, Morocco, Spain, Italy, Tunisia, and Turkey. The results obtained by applying statistical procedures have given pieces of evidence that oil samples have shown the trend to cluster according to the different climatic areas of growing environment of fruits. Some confusion has been observed for samples coming from neighboring countries having similar climates.

Sterols, triterpene dialcohols, long-chain aliphatic alcohols and higher triterpene alcohols were determined in three fruit oil kinds (seed, pulp and whole fruit oils). Seven major Italian olive fruit varieties from the same environment were considered. Results of this research suggested that the compositional data concerning the above analytical fractions were effective in discriminating between seed and pulp oils. The seed oil fraction did not substantially modify the sterol and alcohol composition of the whole fruit oil (mixture of seed and pulp oils), the percentage weight of the seed ($2%) being far lower than that of the pulp ($85%) (whole fruit weight basis). Based on the concentrations of the above components and using appropriate statistical parametric or non-parametric multivariate techniques, the genetic origin (olive variety) of the three fruit oil kinds was characterised.