Agriculture Reference
In-Depth Information
POSTHARVEST TREATMENTS AND
STORAGE TECHNOLOGIES
subjected to a small suite of antifungal measures, for ex-
ample, a hot-water spray with a dissolved fungal inhibitor,
packed dry into punnets, gassed with a MA, and heat sealed
with an anticondensation film (Scott et al., 1982; Olesen
et al., 2004; De Reuck et al., 2009). The punnets would be
transported and marketed under refrigeration. The optimum
temperature recommended for the storage of lychee seems
to depend on the method of assessment. The optimum
temperature for storage of lychee is approximately 5 C
(Table 13.1), although fruit stored at 10 C can last almost
as well, with less risk of condensation in the pack. How-
ever, precooling, fungicide treatment, packaging, storage,
transport, and distribution require enhancement in terms
of integration and optimization to facilitate marketing of
increasing lychee fruit supplies. A MA of 3% to 5% O 2
and 3% to 5% CO 2 was mentioned earlier (Jiang and Fu,
1999b), but other mixtures and gases, such as nitrous oxide,
deserve attention.
International grade standards and appropriate posthar-
vest handling and cold chain protocols need to be estab-
lished and applied. In addition to secure overseas markets
for lychee fruit, fruit fly quarantine issues need to be re-
solved (Jiang et al., 2006b). In this context, appropriate ef-
fective disinfestations protocols that include heat treatments
and gamma or ionizing radiation need to be optimized
and accepted by authorities (McLauchlan et al., 1992;
Follett and Sanxter, 2001; Armstrong and Follett, 2007).
Future improvement of postharvest handling systems for
lychee fruit should also include consideration of prehar-
vest management and handling influence on postharvest
quality.
The current storage and shipping practices can be sum-
marized as follows. (1) For local markets, harvest at full
ripeness is preferable. For distant markets, harvest occurs
before fruits turn red. Fruits should be kept in cool, dry, and
well-ventilated rooms. (2) Fruit is treated by burning sulfur
powder for 20
Postharvest losses: causes and remedies
Postharvest decay of lychee fruit is one of the major obsta-
cles in the postharvest fruit chain, reducing the commercial
value (Coates et al., 2005). A wide range of fungi can cause
decay of lychee fruit (Coates et al., 1995; De Jager et al.,
2003). The main pathogen isolated from Chinese lychee
is identified as Peronophythora litchi (Chen et al., 2001).
The predominant fungal genera associated with lychee in
South Africa are Penicillium, Phomopsis, Pestalotiopsis,
Trichoderma, Alternaria, Botryosphaeria, and Fusarium
spp. (Jiang et al., 2006b). Penicillium spp. has been isolated
more regularly from lychee fruit in the postharvest envi-
ronment. After SO 2 fumigation, Penicillium spp. becomes
a major problem in the lychee export industry (Sivaku-
mar et al., 2010). Cross-contamination can occur in the
export chain, often due to saprophytic Penicillium spp. It
is also confirmed that SO 2 fumigation affects the natural
ecological balance and enhances decay due to colonization
by a range of saprophytic Penicillium spp. The spores of
these saprophytes are usually present in containers used
for export shipment. Microcracks observed during fruit de-
velopment and caused during the postharvest handling can
provide a port of entry for decay pathogens that colonize the
fruit surface. Postharvest remedies to pathogen control that
have been investigated for lychee fruit include temperature
management, application of fungicides and biological con-
trol agents, heat treatments, various packaging options, and
modified atmosphere (MA) or controlled atmosphere (CA)
storage (Brown et al., 1984; Huang and Scott, 1985; Jacobi
et al., 1993; Jiang and Fu, 1999b; Caro and Joas, 2005;
Sivakumar and Korsten, 2006; Guadarrama et al., 2008;
De Souza et al., 2010; Somboonkaew and Terry, 2010b).
Among these treatments, SO 2 fumigation is considered the
most effective and practical treatment in lychee industry
(Lichter et al., 2000; Sivakumar et al., 2010).
30 min at ambient temperature, vaporizing
liquid SO 2 from pressurized cylinders, or chemical disso-
ciation of sulfite compounds, followed by an acidic dip.
Application of fungicides such as thiabendazole, iprodi-
one, and prochloraz as replacements of sulfur fumigation
to control postharvest disease of lychee fruit is also used.
(3) Fruits can be stored for 1 month at 2 -3 C with a high
relative humidity of 90-95%. (4) Fruits should be packed in
a shallow basket or crate lined with newspaper. Care should
be taken to avoid crushing of fruits and damage to skin. It is
particularly noted that implementing quality management
practices in lychee storage and shipping chain should con-
sider the integrated technology to better maintain overall
fruit quality in relation to consumer acceptance in terms
Current storage and shipping practices
Ideally, fruit should be shipped on the day of harvest. The
postharvest handling system of lychee fruit typically in-
cludes fungicide treatment, packaging, storage, transport,
and distribution, each of which can greatly influence fruit
quality (Chen et al., 2001). Sorting and grading, precool-
ing, and fungicide treatment for lychee fruit are commer-
cial essentials (Jiang et al., 2006b). The harvested fruit
would be initially placed in a cool room to remove the
field heat and then sorted on a roller conveyor in the pack-
inghouse (Ketsa and Leelawatana, 1990). It might then be
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