Fig. 1. Chemical structures of the investigated lignans.

Fig. 2. Applied procedures for the extraction of lignans from stones and pulp of Arbequina and Taggiasca fruits.

Fig. 3. Scheme of the extraction method that presents some similarities with the malaxation process, applied to olive pulp of Taggiasca.

Fig. 4. Chromatographic profile at 280 nm, TIC and EI profiles of the ether fraction from methanol extract at reflux from Taggiasca powdered stone: ion at m/z 357 and m/z 415, for Pr, and Ac–Pr, respectively.

Fig. 5. Chromatographic profile at 280 nm (a) of the methanol Taggiasca stone extract: ion at m/z 415 (b), m/z 373 (c), and m/z 357 (d), for Pr, Ac–Pr, and OH–Pr, respectively, are shown.

Fig. 6. MS spectra in negative ionization mode and fragmentor 100 V, of Ac–Pr (a), Pr (b), and OH–Pr (c).

Fig. 7. Flow chart on the products obtained from milling of the whole fruit and occurrence of lignans. The quantitative range for each cv has been extrapolated from the papers cited in the introduction.

Distribution of the three lignans in the stone extracts

The quantitative evaluation was carried out by ES/MS in negative ionization mode. These data are expressed as mg/g dried weight and they are an average of three determinations (% RSD below 10%).