**8.5 Olive maturation**

366 Olive Oil – Constituents, Quality, Health Properties and Bioconversions

analysis of oleocanthal, Beauchamp and colleagues (Beauchamp et al., 2005) in collaboration with Impellizzeri et al. (Impellizzeri and Lin, 2006), developed an extraction and quantification method specific for this compound. Utilizing this method, Impellizeri et al. (Impellizzeri and Lin, 2006) and Franconi et al. (Franconi et al., 2006) found the concentration of oleocanthal ranged between 8.3 ± 4.0 and 189.9 ± 2.7 mg/kg. An adaption of the Beauchamp and co-workers' (Beauchamp et al., 2005) methodology, was also utilized in studies by Cicerale and colleagues (Cicerale et al., 2009a, Cicerale et al., 2009b, Cicerale et al., 2011b, Cicerale et al., 2011a). The resultant oleocanthal concentrations in these investigations were similar to those found by Franconi et al. (Franconi et al., 2006) and Impellizzeri et al. (Impellizzeri and Lin, 2006) (53.9 ± 7.7 to 152.2 ± 10.5 mg/kg). However, a number of methods not specific for oleocanthal have also been used to quantify this compound and may account partially for the large variation in oleocanthal concentration observed (5.0 ± 0.3 – 498.0 ± 47.0 mg/kg) (Vierhuis et al., 2001, Servili et al., 2007b, Servili et al., 2007a, Romero et al., 2002, Morello et al., 2004, Tovar et al., 2001, De Stefano et al., 1999, Montedoro et al., 1992, Gomez-

Geographic region in which olives are grown has been shown to be an important factor in regards to phenolic composition and concentration in general (Vinha et al., 2005, Cerretani et al., 2005). Beauchamp et al. (Beauchamp et al., 2005) demonstrated that EVOOs produced in differing countries had variable oleocanthal concentrations. For instance, EVOO produced in the U.S.A., contained a low concentration of oleocanthal (22.6 ± 0.6 mg/kg), however EVOOs produced in Italy contained some of the highest quantities of this

Several studies have demonstrated differences between olive cultivar and oleocanthal concentration in the oil produced. In one study, the Coratina cultivar EVOO contained 78.2 ± 0.5 mg/kg oleocanthal, whereas the Oliarola cultivar EVOO contained 21.0 ± 0.8 mg/kg oleocanthal, a 3-fold difference (De Stefano et al., 1999). In another study, EVOO produced from the Frantoio cultivar had an oleocanthal concentration of 43.8 ± 3.1 mg/kg, whilst EVOO obtained from the Coratina cultivar, contained a 2-fold higher oleocanthal content at 92.8 ± 7.8 mg/kg (Servili et al., 2007b). A study by Franconi and colleagues (Franconi et al., 2006) also showed significant differences in oleocanthal concentration amongst differing olive cultivars. For instance, an oleocanthal concentration of 8.3 ± 4.0 mg/kg and 53.0 ± 12.0 mg/kg in EVOOs

The concentration of phenolic compounds in EVOO is greatly affected by agricultural techniques used in the cultivation of olive fruit (Gomez-Rico et al., 2006, Ayton et al., 2007). Tovar and co-workers (Tovar et al., 2001) demonstrated that with increased irrigation applied to the olive tree, oleocanthal concentration decreased. For instance, in the EVOO obtained from the least irrigated olive trees (46 mm water per year) oleocanthal concentration was determined to be 50.9 ± 6.5 mg/kg. For the EVOO produced from highly irrigated olive trees (259 mm water per year), oleocanthal concentration was 23.1 ± 1.3 mg/kg. Gomez-Rico et al.

produced from the Taggiasca and Seggianese cultivars respectively, was noted.

Alonso et al., 2003, Gomez-Rico et al., 2006, Allouche et al., 2007)

**8.2 Geographic region** 

**8.3 Cultivar** 

compound (up to 191.8 ± 2.7 mg/kg).

**8.4 Agricultural methods** 

Maturation of the olive fruit at harvest is an important predictor of the phenolic composition and concentration in EVOO. In regards to oleocanthal, one study found that with extended picking date and increased olive fruit ripeness, the concentration of oleocanthal in EVOO decreased by 43% (148.0 mg/kg to 84.0 mg/kg) over a short two month period (Morello et al., 2004). The researchers, Gomez-Rico et al. (Gomez-Rico et al., 2006) also observed a similar decrease of 20% and 54% in oleocanthal with increasing maturity index using two olive cohorts.
