9.3.2.3 Environmental Conditions
Olive is a xerophyte plant, and it needs a mild climate, as it is particularly susceptible
to fast temperature drops below À8
C. Its full potential is described to be between
22 and 32
C. At higher latitudes, an increase in oleic acid content and a higher ratio
of unsaturated to saturated fatty acids are typically expected. The environmental
conditions can decrease the activity of certain hydrolytic enzymes which act on
phenols (Patumi et al. 1999).
Several studies have been conducted on the effect of soil salinity and irrigation
water on the production and VOO fatty acid profile, but so far scarce and contradictory results have been published in relation to the effects on organoleptic characteristics. Ahmed et al. (2009) reported an increase in the concentration of phenolic
compounds such as tyrosol, hydroxytyrosol and vanillic acid, and a lowering in the
ratio of unsaturated to saturated fatty acids, with an increase in water salinity.
The influence of the organic agronomical practice on the VOO composition and
flavour characteristics has been poorly investigated. Ninfali et al. (2008) reported
higher concentrations of phenolic compounds from organic than non-organic VOOs
in the first year of the experiment, while this difference was not significant over the
second and third year. Organic VOOs have shown a stronger note of “hay” and
“artichoke”. Non-organic oils presented more markedly floral notes of “fresh grass”
and “fruity”. However, the results are not consistent in all the years and are strongly
influenced by climate change over the years (Ninfali et al. 2008).
Water deficit represents one of the main environmental limiting factors on the
olive production potential, caused by the decrease of the fruit endogenous esterases.
Rainfall has prominent influence on EVOO volatiles. Compounds such as hexanal
and isobutyl acetate were negatively correlated to the rainfall. The amount of water
applied to the orchard can modify the fatty acid ratio; a higher concentration of
monounsaturated and polyunsaturated fatty acids is obtained at higher water volumes applied (Salas and Sanchez 1997). A clear inverse correlation was also
reported between the amount of irrigation water applied and the intensity of the
EVOO bitter note. Gomez-Rico et al. (2006) indicated that phenolic compounds are
strongly affected by the water availability during fruit development. The authors
used three water management systems: no added water, fully water addition and
controlled deficit irrigation according to the method proposed by FAO. It was shown
that polyphenol content decreases at increased water supplied to the orchard, and
secoiridoid derivatives of hydroxytyrosol decreased more than those of tyrosol.
However, increase of volatile compounds was obtained under irrigation compared
to rain-fed conditions.
Greater water availability seems also to affect favourably the concentration of
volatile compounds, especially trans-2-hexenal, cis-3-hexen-1-ol and hexanal. Some
other volatile compounds were not reported to be subject to variations; these are
1-penten-3-one and 1-penten-3-ol, which are linked more to seasonal factors and
ripening degree than to the irrigation practices (Gomez-Rico et al. 2006). In
9 Olive (Olea europaea)
225
Olive is a xerophyte plant, and it needs a mild climate, as it is particularly susceptible
to fast temperature drops below À8
C. Its full potential is described to be between
22 and 32
C. At higher latitudes, an increase in oleic acid content and a higher ratio
of unsaturated to saturated fatty acids are typically expected. The environmental
conditions can decrease the activity of certain hydrolytic enzymes which act on
phenols (Patumi et al. 1999).
Several studies have been conducted on the effect of soil salinity and irrigation
water on the production and VOO fatty acid profile, but so far scarce and contradictory results have been published in relation to the effects on organoleptic characteristics. Ahmed et al. (2009) reported an increase in the concentration of phenolic
compounds such as tyrosol, hydroxytyrosol and vanillic acid, and a lowering in the
ratio of unsaturated to saturated fatty acids, with an increase in water salinity.
The influence of the organic agronomical practice on the VOO composition and
flavour characteristics has been poorly investigated. Ninfali et al. (2008) reported
higher concentrations of phenolic compounds from organic than non-organic VOOs
in the first year of the experiment, while this difference was not significant over the
second and third year. Organic VOOs have shown a stronger note of “hay” and
“artichoke”. Non-organic oils presented more markedly floral notes of “fresh grass”
and “fruity”. However, the results are not consistent in all the years and are strongly
influenced by climate change over the years (Ninfali et al. 2008).
Water deficit represents one of the main environmental limiting factors on the
olive production potential, caused by the decrease of the fruit endogenous esterases.
Rainfall has prominent influence on EVOO volatiles. Compounds such as hexanal
and isobutyl acetate were negatively correlated to the rainfall. The amount of water
applied to the orchard can modify the fatty acid ratio; a higher concentration of
monounsaturated and polyunsaturated fatty acids is obtained at higher water volumes applied (Salas and Sanchez 1997). A clear inverse correlation was also
reported between the amount of irrigation water applied and the intensity of the
EVOO bitter note. Gomez-Rico et al. (2006) indicated that phenolic compounds are
strongly affected by the water availability during fruit development. The authors
used three water management systems: no added water, fully water addition and
controlled deficit irrigation according to the method proposed by FAO. It was shown
that polyphenol content decreases at increased water supplied to the orchard, and
secoiridoid derivatives of hydroxytyrosol decreased more than those of tyrosol.
However, increase of volatile compounds was obtained under irrigation compared
to rain-fed conditions.
Greater water availability seems also to affect favourably the concentration of
volatile compounds, especially trans-2-hexenal, cis-3-hexen-1-ol and hexanal. Some
other volatile compounds were not reported to be subject to variations; these are
1-penten-3-one and 1-penten-3-ol, which are linked more to seasonal factors and
ripening degree than to the irrigation practices (Gomez-Rico et al. 2006). In
9 Olive (Olea europaea)
225