Evaluation of phenolic fraction in edible olive oils obtained by different technological systems

Virgin olive oil is well known for its content of phenolic compounds, that are thought to have health-promoting properties (Murkovic et al., 2004). The major phenolic compounds identified and quantified in olive oil belong to three different classes: simple phenols (hydroxytyrosol, tyrosol), secoiridoids (aglycones of oleuropein and ligstroside and their respective dialdehydic derivatives) and lignans [(+)-1- acetoxypinoresinol and (+)-pinoresinol]. Several factors can influence the qualitative and quantitative presence of phenolic compounds in the oil. In fact, both agronomical choices, technological variables and storage factors may cause significant variations in terms of phenolic content (Cerretani et al., 2005). The antioxidant power of phenolic compounds in virgin olive oil (VOO) has also been a subject of considerable interest, both for its chemoprotective effect in human health (Briante et al., 2001; Leenen et al., 2002; Caponio et., 2001) and because it is the most important factor in the high oxidative stability (shelf life) of VOO (Caponio et al., 2001., Baldioli et al., 1996). Virgin olive oil is well known for its content of phenolic compounds, that are thought to have health-promoting properties (Murkovic et al., 2004). The major phenolic compounds identified and quantified in olive oil belong to three different classes: simple phenols (hydroxytyrosol, tyrosol), secoiridoids (aglycones of oleuropein and ligstroside and their respective dialdehydic derivatives) and lignans [(+)-1- acetoxypinoresinol and (+)-pinoresinol]. Several factors can influence the qualitative and quantitative presence of phenolic compounds in the oil. In fact, both agronomical choices, technological variables and storage factors may cause significant variations in terms of phenolic content (Cerretani et al., 2005). The antioxidant power of phenolic compounds in virgin olive oil (VOO) has also been a subject of considerable interest, both for its chemoprotective effect in human health (Briante et al., 2001; Leenen et al., 2002; Caponio et., 2001) and because it is the most important factor in the high oxidative stability (shelf life) of VOO (Caponio et al., 2001., Baldioli et al., 1996). The antioxidant activity of VOO components has been related to the protection against important chronic and degenerative diseases such as coronary hearth diseases, ageing neurodegenerative diseases, and tumors of different localizations (Hodge et al., 2004). Besides mentioned preventive actions, in a recent paper (Beauchamp et al., 2005), it was been reported the anti-inflammatory action of a phenolic compound present in VOO (named oleocanthal). In particular, they have found that oleocanthal is both a potent non-streroidal anti-inflammatory agent (similar to ibuprofene), and a power antioxidant (similar to α-tocopherol). Moreover the phenolic compounds also contribute to organoleptic properties of VOOs and are commonly described as bitter and pungent (Gutierrez-Rosales et al., 1992; Gutierrez- Rosales et al., 2003). In recent studies it was observed a relationship between bitter and pungency sensory properties and ligstroside or aldehydic form of oleuropein aglycone content (Tovar et al., 2001).