polyunsaturated fatty acids when the olive drupe is crushed, and it is released from
the cell membrane, so it is exposed to the lipids in the vacuole, after the action of
acyl-hydrolase. Volatile compounds such as hexanal, 1-hexanol, hexyl-acetate, cis-/
trans-3-hexenal, cis-/trans-3-hexen-1-ol and cis-/trans-2-hexenyl-acetate are
biosynthesised in this reaction. Compounds such as hexanal, (E)-2-hexenal, (Z)-3hexenal, hexan-1-ol, (Z)-3-hexen-1-ol, hexyl acetate and (Z)-3-hexenyl acetate are
the most abundant volatiles in VOOs (Angerosa et al. 1999; Vichi et al. 2003).
Among volatile compounds, those related to the sensory note described as
“green” are C6 aliphatic compounds, hexanal, cis-3-hexenal, trans-2-hexenal,
hexanol, cis-3-hexenol, trans-2-hexen-1-ol and the corresponding esters (Gomes
da Silva et al. 2011).
The following volatile compounds account for approximately 80% of the total:
• C6 aldehydes (hexanal, cis-3-hexanal, trans-2-hexanal)
• Alcohols (hexanol, cis-3-hexenol, trans-2-hexenol)
• Esters (hexyl acetate, cis-3-hexenyl acetate (Sánchez and Harwood 2002; Conde
et al. 2008; Angerosa 2002)
C6 volatile compounds are the major components of VOO volatiles and mainly
contribute to its green odour (fruity and/or green olives) (Guth and Grosch 1991;
Morales et al. 1997). The essential role played by hexanal and trans-2-hexenal on the
green attributes was confirmed by Angerosa et al. (2000), who also reported the
correlation between fruity, leaf, almond, banana, freshly cut grass, walnut husk, wild
flowers, tomato, bitter, pungent and sweet attributes and the concentrations of
compounds deriving from the LOX pathway and the total amount of the
secoiridoids.
Some correlations between the level of total phenolic compounds and aroma
compounds with sensory descriptors were also found in VOO. In particular, higher
concentration of 1-penten-3-one and phenolic compounds causes the increase of leaf
odour, and an increase in the phenolic concentration causes the increase of walnut
husk odour (Angerosa et al. 2000).
9.3.1.1 Phenolic Compounds
Olive oil is rich in bioactive compounds, which are commonly classified as
non-polar, found in the unsaponifiable fraction (squalene, tocopherols, sterols and
triterpenic compounds), and polar compounds. The second group comprises phenolic compounds, which are often improperly referred to as “polyphenols”. Other
authors refer to them as “biophenols” to emphasise their natural occurrence, or
generally phenolic compounds (Visioli et al. 2002).
The characteristic bitter taste of fresh olive fruits is due to the high content of
phenolic compounds. VOOs also possess a considerable charge of phenolic compounds resulting in a more or less pronounced bitter-pungent character. The bitter
sensation of olive oils has been associated with secoiridoid derivatives of
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N. Caporaso and D. Boskou
the cell membrane, so it is exposed to the lipids in the vacuole, after the action of
acyl-hydrolase. Volatile compounds such as hexanal, 1-hexanol, hexyl-acetate, cis-/
trans-3-hexenal, cis-/trans-3-hexen-1-ol and cis-/trans-2-hexenyl-acetate are
biosynthesised in this reaction. Compounds such as hexanal, (E)-2-hexenal, (Z)-3hexenal, hexan-1-ol, (Z)-3-hexen-1-ol, hexyl acetate and (Z)-3-hexenyl acetate are
the most abundant volatiles in VOOs (Angerosa et al. 1999; Vichi et al. 2003).
Among volatile compounds, those related to the sensory note described as
“green” are C6 aliphatic compounds, hexanal, cis-3-hexenal, trans-2-hexenal,
hexanol, cis-3-hexenol, trans-2-hexen-1-ol and the corresponding esters (Gomes
da Silva et al. 2011).
The following volatile compounds account for approximately 80% of the total:
• C6 aldehydes (hexanal, cis-3-hexanal, trans-2-hexanal)
• Alcohols (hexanol, cis-3-hexenol, trans-2-hexenol)
• Esters (hexyl acetate, cis-3-hexenyl acetate (Sánchez and Harwood 2002; Conde
et al. 2008; Angerosa 2002)
C6 volatile compounds are the major components of VOO volatiles and mainly
contribute to its green odour (fruity and/or green olives) (Guth and Grosch 1991;
Morales et al. 1997). The essential role played by hexanal and trans-2-hexenal on the
green attributes was confirmed by Angerosa et al. (2000), who also reported the
correlation between fruity, leaf, almond, banana, freshly cut grass, walnut husk, wild
flowers, tomato, bitter, pungent and sweet attributes and the concentrations of
compounds deriving from the LOX pathway and the total amount of the
secoiridoids.
Some correlations between the level of total phenolic compounds and aroma
compounds with sensory descriptors were also found in VOO. In particular, higher
concentration of 1-penten-3-one and phenolic compounds causes the increase of leaf
odour, and an increase in the phenolic concentration causes the increase of walnut
husk odour (Angerosa et al. 2000).
9.3.1.1 Phenolic Compounds
Olive oil is rich in bioactive compounds, which are commonly classified as
non-polar, found in the unsaponifiable fraction (squalene, tocopherols, sterols and
triterpenic compounds), and polar compounds. The second group comprises phenolic compounds, which are often improperly referred to as “polyphenols”. Other
authors refer to them as “biophenols” to emphasise their natural occurrence, or
generally phenolic compounds (Visioli et al. 2002).
The characteristic bitter taste of fresh olive fruits is due to the high content of
phenolic compounds. VOOs also possess a considerable charge of phenolic compounds resulting in a more or less pronounced bitter-pungent character. The bitter
sensation of olive oils has been associated with secoiridoid derivatives of
220
N. Caporaso and D. Boskou