Polyphenols - Fruit Ripening: Physiology, Signalling and Genomics - page 167

et al. , 2011). Moreover, normal dietary
intake is unlikely to exert any protective
effect, because of the small quantities
consumed (Manach et al. , 2006). However,
the antioxidant action may be exerted in the
digestive tract (Halliwell et al. , 2005), and
catabolites formed by microbial transform-
ation in the colon may be absorbed and also
show biological activities.
The biological effects of polyphenols
may implicate other mechanisms such as
antimicrobial properties, an impact on
intestinal fl ora and modulation of cell
signalling pathways (Manach et al. , 2009).
In particular, a health claim has been
approved for the use of A-type pro-
cyanidins from cranberries for prevention
of urinary tract infection. Finally, other
minor polyphenol classes, including iso-
fl avones (which are abundant in legumes
and especially soybean), coumestans and
lignans, are reported to show phyto-
oestrogenic properties (Kuhnle et al. , 2007).

raspberry (Remberg et al. , 2010), but this
result was not confi rmed by McDougall et
al. (2011).
Low temperature stimulates antho-
cyanin accumulation by upregulating the
expression of biosynthetic genes in apple
and pear (Ubi et al. , 2006; Steyn et al. ,
2009), in grape (Yamane et al. , 2006) and
also in orange (Crifò et al. , 2011). In mature
oranges, the response to cold treatment is
strictly observed in blood oranges but not
in common oranges. Furthermore, in apple,
the environmental temperatures also
modulate the expression of regulatory
genes (Ban et al. , 2007; Lin-Wang et al. ,
2010).

Light
Several studies have reported that light
exposure stimulates accumulation of
piceid (Adrian et al. , 2000) and of PAs,
fl avonols and anthocyanin in grape berries
(Cortell and Kennedy, 2006; Koyama et al. ,
2012). Howewer, the impact of light
exclusion on PA biosynthesis is limited
(Koyama et al. , 2012). This increase more
specially affects B-ring trihydroxylated
compounds (Cortell and Kennedy, 2006;
Fujita et al. , 2007). In grape berries,
fl avonol biosynthesis is also induced by
light (Downey et al. , 2004; Matus et al. ,
2009), even during developmental stages
when fl avonols are normally not
synthesized. Light also enhances antho-
cyanin synthesis in many other fruit
species such as apple (Kim et al. , 2003),
pear (Steyn et al. , 2004) and peach
(Kataoka and Beppu, 2004; Tsuda et al. ,
2004). Nevertheless, this response appears
to depend on cultivars. In Syrah berries,
anthocyanin synthesis is not infl uenced by
shading (Downey et al. , 2004), whereas
Cabernet Sauvignon grape berries contain
fewer anthocyanins when shaded from
sunlight (Jeong et al. , 2004). Similarly,
tomato fruit from different cultivars are
also differentially affected by light
exposure. In most cases, the MYB
transcription factor appears to be the
primary determinant of fruit pigmentation
in response to light, such as in apple,

9.4 Fruit Polyphenol Composition

9.4.1 Factors affecting fruit phenolic
composition

Several factors have been reported to affect
the fruit polyphenolic composition.

Temperature

In persimmon, cold stress has been
demonstrated to stimulate PA accumu-
lation in fruit when applied 1 week after
bloom (WAB) but has no signifi cant effect
when applied 5 weeks after bloom. The
most signifi cant impact was measured on
trihydroxylated subunits (gallocatechin
and epigallogatechin), rather than on
dihydroxylated units (catechin and
epicatechin or galloylated units). On the
other hand, no signifi cant correlation
between temperature and PA accumulation
was detected on grape berries (Cohen et al. ,
2012), despite a similar early application of
thermal stress (10-12 days after anthesis).
Ellagitannins concentration was sig-
nifi cantly increased with temperature in