**8.6 Processing**

In general, the processing of olive fruit to oil has a substantial effect on the concentrations of phenolic compounds in EVOO (Kalua et al., 2006b, Cerretani et al., 2005, Vierhuis et al., 2001, Romero et al., 2004, Gimeno et al., 2002). EVOO produced by the traditional processing method (whereby the entire olive fruit is crushed, including the stone), was found to contain lower quantities of oleocanthal (43.8 ± 3.1 mg/kg) compared to EVOO produced by the stoning method in which the olive stone is removed before crushing (54.8 ± 3.1 mg/kg). The researchers from this study hypothesized that the differences may be due to the increased peroxidase (POD) activity that tends to accompany the crushed olive stone, which has an oxidizing effect on oleocanthal concentration (Servili et al., 2007b).

EVOO produced under nitrogen (N2) flushing and with use of enzymatic treatment (which aids cell wall degradation and thus improves phenolic extraction) (Vierhuis et al., 2001), was found to contain oleocanthal concentrations of 31.4 ± 1.0 mg/kg. EVOO produced with no added enzymes and without nitrogen (N2) flushing (therefore allowing oxygen (O2) to be present) was found to contain a lower amount of oleocanthal (24.8 ± 1.9 mg/kg). EVOOs produced with use of N2 flushing alone and enzymatic treatment alone, contained 28.4 ± 1.4 mg/kg and 29.4 ± 0.8 mg/kg oleocanthal respectively (Vierhuis et al., 2001).

EVOOs produced using two-phase centrifugation which uses no added water in the processing method, was found to contain a higher phenolic concentration compared to EVOOs obtained from three-phase centrifugation which utilizes a considerable amount of water (approximately 400 L/h) (De Stefano et al., 1999). De Stefano and et al. (De Stefano et al., 1999) found oleocanthal concentration in EVOO obtained from the two-phase centrifuge to be higher (78.2 0.5 mg/kg) than that produced from the three-phase method (67.3 ± 2.6 mg/kg). The addition of water in the three-phase centrifugation method, may have a reducing effect on the more water-soluble phenolics from the oil phase during processing, thus reducing the concentration of oleocanthal in the resultant EVOO (Cicerale et al., 2009c).

Oleocanthal: A Naturally Occurring Anti-Inflammatory Agent in Virgin Olive Oil 369

of oleocanthal, have prompted research to further verify its therapeutic potential. Oleocanthal has been shown, *in vitro*, to exert beneficial physiological effects in terms of neurodegenerative disease, joint-degenerative disease and cancer. Therefore, it has been postulated that the long term ingestion of this compound via EVOO consumption may have significant health promoting action over time, thereby reducing the development of chronic disease.

However, the studies conducted on the health promoting potential of oleocanthal have involved *in vitro* investigations and it is difficult to extrapolate data from *in vitro* studies to actual physiological benefits. *In vivo* research is therefore required to substantiate the *in vitro* findings. Furthermore, the bioavailability of oleocanthal has not been adequately investigated. To date, only one study has reported on the post-ingestive fate of oleocanthal, noting that it was readily metabolized however the mechanism was not investigated. The degree to which oleocanthal is metabolized is an important consideration when reviewing the health benefits associated with ingestion, and further research on this is warranted. The link between the perceptual aspects of oleocanthal and health benefits is the notion that variation in sensitivity to oleocanthal oro-pharyngeal irritation may relate to potential differences in sensitivity to the anti-inflammatory action of this compound and this is also

Finally, it was not the purpose of this overview to attribute the health benefits of the Mediterranean diet solely to one component and we did not aim to credit oleocanthal as being the lone therapeutic agent contained in EVOO. Other constituents of the Mediterranean diet and EVOO will contribute, either with independent actions, or in a synergistic and complementary manner to impart beneficial health effects (Lucas et al., 2011, Fogliano and Sacchi, 2006). However, the studies conducted to date investigating the pharmacological actions of oleocanthal are encouraging and show that this compound possesses substantial health benefiting properties. Further research will no doubt provide new insight into the pharmacological potential of oleocanthal and assess the role that

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