*3.1. Qualitative Parameter of Messinian Olive Oils, Greece*

As shown in Figure 2, of the 71 virgin olive oils analyzed, all are classified as extra virgin olive oil (EVOO), as far as the qualitative indices are concerned, according to the European Regulation (EEC) 2568/91 as amended, with the exception of two samples in total, which were not within the accepted acidity value of 0.80% and excluded for further analysis. The content of free acids is an important quality factor, extensively used as the major criterion for the classification of olive oil at various commercial grades. −1 "Kalamata PDO olive oil"

– **Figure 2.** (**a**) Scatter plots visualizing the qualitative parameters (**a**) acidity, (**b**) peroxide value (**c**) K<sup>232</sup> extinction coefficient and (**d**) K<sup>268</sup> extinction coefficient, respectively, of the 71 examined Messinian olive oil samples numbered as K1–K71, *N* = 71. Dotted line: limits according to EEC/2568/91 for extra virgin olive oil (EVOO) category; straight line: limits according to Council Regulation (EC) 510/2006 for Kalamata Protected Designation of Origin (PDO) olive oil [20,21,23].

**–** – ≤0.80 ≤ – ≤ ≤ According to the relevant Commission Regulation for Kalamata PDO olive oil, stricter quality specifications compared to EU Regulation 2568/91 have been laid down. [20,21]. As shown in Figure 2, a high percentage of the examined Messinian olive oil samples (88.73%) did not exceed the threshold of 0.50% in acidity, which is defined as the upper limit for Kalamata PDO olive oils. The mean acidity value was 0.34% and ranged from 0.17 to 0.76 (Table 1). In addition, peroxide value and spectrophotometric analysis, crucial indices of olive oil oxidation, were within and quite below the upper limit established by EC Regulation for the EVOO category as presented in Figure 2. In particular, peroxide value for the tested samples ranged from 3.64 to 11.96 meq. O<sup>2</sup> kg −1 , with a mean value

studies have shown that each variety has a characteristic sterol "fingerprint". Therefore, those minor

deviations of the main sterols present in the olive oil sampled. The main sterols detected were β–

– ≤ ≤ – ≤ ≤

–

–

with β

at 7.24 meq. O<sup>2</sup> kg−<sup>1</sup> (Table 1). Likewise, K<sup>232</sup> and K<sup>268</sup> values had a mean value of 1.55 and 0.13, respectively, with only one sample surpassing the Kalamata PDO limit for K<sup>268</sup> value.


**Table 1.** Qualitative parameters of Messinian olive oils.

Results are expressed as the means ± standard deviation (SD). *N* = 69. EEC = European Commission, EVOO = Extra Virgin Olive Oil, PDO = Protected Designation of Origin.

It should be noted that as peroxide value is a quality indicator of the primary products of auto-oxidation (hydroperoxides) of an olive oil, poor post-extraction conditions (e.g., inappropriate storage and packaging) may result to a fast increase in peroxide value above the defined limit of 14 meq O2·kg−<sup>1</sup> , excluding olive oils from the PDO labeling.

In general, the above observations depict the highest quality of Messinian olive oil production, one of the most important olive-growing regions in Greece, but most importantly highlight how crucial it is to retain those qualitative characteristics, especially with the recent approval of the European commission to expand "Kalamata PDO olive oil" in the whole regional unit of Messinia (21).
