Kiwifruit - Tropical and Subtropical Fruits: Postharvest Physiology, Processing and Packaging - page 467

and three flavonoid compounds (quercetin, quercetin-3-O-
α

Controversial effects of pullulan-based coating on higher
internal ethylene production and accelerated ripening (Diab
et al., 2001) and better shelf life (Xu et al., 2001, 2003) have
been reported for 'Hayward' variety. The use of other coat-
ings (calcium caseinate, chitosan, PrimaFresh 50-V, and
Semperfresh) has been investigated in hardy kiwifruit for
reducing moisture loss without compromising the ripening
(Fisk et al., 2008).

-D-glucoside). Among
them, only gallic acid is found to be effective in mycelial
growth and spore germination of B. cinerea at relatively
high concentrations. Therefore it has been suggested that
gallic acid can be a safer and more acceptable alternative
to current synthetic fungicides controlling soft rot decay of
kiwifruits during postharvest storage (Oh et al., 2008).

-L-rhamnoside, quercetin-3-O- β

Ozone treatment
Photocatalytic ozonation is effective in inactivating coni-
dial germination but is ineffective in controlling latent in-
fection in kiwifruit tissue (Hur et al., 2005). The authors
have suggested that the physical barriers of kiwifruit tissue
seem to protect the pathogens from the reactive oxygen
species generated during the photocatalytic ozonation pro-
cess. Conversely, Barboni et al. (2010) reported that ozone
chambers significantly decreased Botrytis contamination
during storage.

Biocontrol agents
The use of yeast (e.g., Candida sake, C. pulcherrima,
Trichosporon pullulans, Galactomyces geotrichum, G.
geotrichum ) as biocontrol agents to induce antagonistic
effects against B. cinerea in kiwifruits has demonstrated
various degrees of success (Cook et al., 1997, 1999; Cook,
2002). The microbes alone or with aid of kiwifruit curing
confer a significant level of biocontrol following appli-
cations made simultaneously with or up to 96 hours after
B. cinerea inoculation (Cook et al., 1999). An additive effect
for fruit curing is only found when the application of the
biocontrol agents is made after 96 hours of fruit curing.
Host resistance mechanisms triggered by curing may not
be specific to the pathogen, B. cinerea , since the biocon-
trol agent is affected/reduced during the first 24-48 hours
of curing. Other micro-organisms ( Cryptococcus lauren-
tii, Rhodotorula rubra ,and Candida pelliculosa )havealso
been shown to be effective against B. cinerea in other fruits
and may represent an opportunity to control gray mold in
kiwifruit (Zhang et al., 2007; Dal Bello et al., 2008).

Short-term N 2 treatment
Short-term anoxic treatment can maintain a high level of
firmness for 14 days at low temperature and reduce the
softening during shelf life. The treatment seems to function
through halting the increases in membrane permeability
that normally occurs during ripening, decreases lipid per-
oxidation and lipoxygenase activity, delays the production
of the oxidative metabolites (superoxide and H 2 O 2 )and
increases the activities of superoxide dismutase and perox-
idase during the storage period (Song et al., 2009). Thus
the firmness of kiwifruit that is achieved by the short-term
N 2 treatment seems to be due to reduced lipid peroxida-
tion, enhanced antioxidant ability and membrane integrity
maintenance (Song et al., 2009).

Irradiation treatments
Ionizing irradiation is an effective tool to control B. cinerea,
D. actinidiae ,and B. dothidea. The D 10 values are 0.18,
0.26, and 0.19 kGy in kiwifruit: only D. actinidiae can
survive at 1 kGy dose (Kim and Yook, 2009). Faster rate of
softening and a slight decrease in the level of soluble sugar
contents and other nutrients have been found in irradiated
kiwifruit, which warrants further research to optimize the
process condition using this technology.

Shelf life extension and quality
As mentioned earlier, cold storage at around 0 ◦ C can effec-
tively maintain the firmness and extends storage life of ki-
wifruits, but development of physiological disorders (Lallu,
1997) and accelerated loss of the fruit firmness occurs after
cold storage (Arpaia et al., 1987; Antunes and Sfakiotakis,
2002b). These disorders also happen when modified atmo-
sphere (MA) (of CO 2 >

Use of edible coating
Positive effects for chitosan coating on the quality of ki-
wifruit have been reported (Du et al., 1997). Chitosan is
especially beneficial against pathogens and can decrease
moisture loss during storage. The application of chitosan
on the fruit skin (which is normally not eaten) does not
cause any negative sensory attributes such as bitterness and
astringency, which are normally encountered with chitosan-
based coatings (Rodriguez et al., 2003).

3%) is used (Harman
and McDonald, 1989). Curing prior to cold storage seems to
alleviate some of the physiological problems encountered
during cold storage. Several studies have demonstrated bet-
ter eating quality for kiwifruit stored at 0 ◦ C compared to
other temperatures (Marsh et al., 2004). For example, more
uniform ripening and better sensorial attributes occur in
fruits (better flavor intensity, less off flavors, greenness and

8% and O 2 <