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. 2017 Mar 29;6(4):25.
doi: 10.3390/foods6040025.

Pigments in Extra-Virgin Olive Oils Produced in Tuscany (Italy) in Different Years

Cristina Lazzerini  1 , Valentina Domenici  2
Affiliations

Pigments in Extra-Virgin Olive Oils Produced in Tuscany (Italy) in Different Years

Cristina Lazzerini et al. Foods. .

Abstract

Pigments are responsible for the color of olive oils, and are an important ingredient that is directly related to the quality of this food. However, the concentration of pigments can vary significantly depending on the climate conditions, harvesting time, and olive cultivars. In this work, we quantified the main pigments in several extra-virgin olive oils produced from a blend of three cultivars (Moraiolo, Frantoio, and Leccino) typical of Tuscany (Italy) harvested in three different years: 2012, 2013, and 2014. Pigments-namely, β-carotene, lutein, pheophytin A, and pheophytin B-were quantified by a method based on the mathematical analysis of the near ultraviolet-visible absorption spectra of the oils. Data were analyzed by a multivariate statistical approach. The results show that the pigments' content of extra-virgin olive oils produced in 2014 can be well distinguished with respect to previous years. This can be explained by the anomalous climate conditions, which strongly affected Italy and, in particular, Tuscany, where the olives were harvested. This study represents an interesting example of how pigment content can be significant in characterizing olive oils. Moreover, this is the first report of pigment quantification in extra-virgin olive oils produced in Tuscany.

Keywords: Tuscany; carotenoid; chlorophyll; lutein; multivariate analysis; olive oils; pheophytin A; ultraviolet-visible spectroscopy; β-carotene.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Extra-virgin olive oil samples of different harvesting years (2012, 2013, and 2014) produced in Tuscany (Italy) from a blend of Leccino, Moraiolo, and Frantoio cultivars. The location of olives’ origin is indicated for all investigated samples.
Figure 2
Figure 2
Example of near ultraviolet-visible (UV-vis) absorption spectrum of an extra-virgin olive oil (EVOO) sample, recorded in the range 390–720 nm. Experimental (red) and fitted (black) curves are reported with the residuals (dotted) curve.
Figure 3
Figure 3
Profile of the four main pigments (β-carotene, lutein, pheophytin A, and pheophytin B) determined by the mathematical analysis of the near UV-vis absorption spectra of the EVOO samples investigated in this work. Samples are labelled from T1 to T37, as shown in Table 1. Three groups of samples can be visualized depending on the year of olive harvesting (2012, 2013, and 2014).
Figure 4
Figure 4
Plot of the parameter “% of lutein” (over the carotenoid fraction) versus the concentration (ppm) of β-carotene for the EVOO samples investigated in this work. Samples are labeled according to the harvest year.
Figure 5
Figure 5
Results of the multivariate analysis. (A) Score plot of the principal component analysis (PCA) modelling, showing the EVOO samples harvested in 2012 (■), 2013 (○), and 2014 (▲); (B) Loading plot of the PCA modelling, showing the variables used for the analysis. P/C: ratio between total amount of chlorophyll derivatives and the total amount of carotenoids.
See this image and copyright information in PMC

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