Antioxidants and Bioactive Compounds in Fruits - Fruit Ripening: Physiology, Signalling and Genomics - page 115

7.5.7 Postharvest nitric oxide treatment Thermal treatments, alone or in

combination with controlled atmosphere
storage, are commonly applied against
invasive pests, for preservation of fruit
quality and for extension of market life.
Such treatments did not adversely affect
the polyphenol content in mango fruit,
although a general decrease was observed
during the progress of fruit ripening (Kim
et al. , 2007). The effect of postharvest hot-
air treatment on the antioxidant system of
stored mature-green tomatoes has also been
monitored, although without a clear
picture emerging (Yahia et al. , 2007). It
should be noted that the temperature
applied in heat treatments is of critical
importance in the effi cacy of the treatment
on both the qualitative profi le and the
antioxidant properties of the fruit com-
modity.
Processing (blanching, freezing, canning
and cooking) generally has a negative
impact on phytochemical concentrations
but is dependent on temperature and
processing time (Serrano et al. , 2011).

The free-radical gas nitric oxide has been
applied recently as a postharvest treatment
with the aim of retarding the ripening
process, based on its antisenescence
activity. Special attention was paid to the
antioxidant response of 'Rojo Rito' peach
fruit in response to nitric oxide treatment.
The treated fruit were characterized by
lower ethylene evolution and respiration
rate and higher fi rmness retention, and a
lower percentage of electrolyte leakage.
These data provide supporting evidence
that nitric oxide might have a benefi cial
effect on the oxidation equilibrium and the
antioxidant capacity of peach fruit (Flores
et al. , 2008). A more recent study,
investigating the effi cacy of nitric oxide
treatment on qualitative attributes of
'Kensington Pride' mango fruit, showed a
suppression of ethylene production and
respiration rate and a delay of fruit
softening, as well as alleviation of chilling
injury symptoms. However, in terms of
phytochemical properties, nitric oxide
treatments did not seem to affect AsA or
carotenoid content and the overall
antioxidant capacity (Zaharah and Singh,
2011).

7.6 Molecular Breeding and Genetic
Manipulation

In recent years, the biosynthetic pathways
leading to the production of most bioactive
compounds including antioxidants have
been elucidated in higher plants. In
addition to plant transformation, modern
plant biotechnology has provided a variety
of available genomic, transcriptomic,
metabolomic and bioinformatic techniques.
It is now possible to establish molecular
markers linked to health-promoting sub-
stances for use in molecular breeding
programmes to create new cultivars,
hybrids and/or transgenic lines with
improved nutritional content (Farre et al. ,
2011; Goldman, 2011; Zhao and Shewry,
2011). It should be noted that this is a
recent trend in breeding programmes,
whereas the emphasis in the last decades
of the 20th century was placed on the
production of cultivars and hybrids
possessing desirable appearance and
disease and pest resistance coupled with

7.5.8 Other postharvest treatments

A recent review presented an overview of
the effect of postharvest elicitors on
phytochemical content and composition in
horticultural produce, as an attempt to be
an integral part of postharvest management
(Schreiner and Huyskens-Keil, 2006). Such
techniques may be applied to both ripening
fruits destined for fresh consumption or to
raw material intended to be used as
functional foods and/or supplements.
Postharvest elicitors are segregated into
physical (low temperature, heat treatment,
ultraviolet and J -irradiation, altered gas
composition) and those of chemical origin;
the latter includes signalling molecules
implicated in the fruit-ripening process,
such as ethylene, salicylic acid and methyl
jasmonate.