Agriculture Reference
In-Depth Information
palletising glue is used to bond the corrugated containers
vertically on the pallet so that only horizontal strapping is
required.
(a)
Cooling, storage and transportation
Cooling and storage
Because rachises and berries are susceptible to deteriora-
tion due to water loss (see 'Physiological disorders'),
grapes are normally forced-air cooled as soon as possible
after harvest. Grapes do not tolerate the wetting associated
with hydro-cooling (bunches are not sufficiently robust and
the presence of free water encourages grey mould and
other diseases). The use of fruit coatings to control water
loss in grapes has given inconclusive results and some
bloom damage has been observed so it is not recommended
(D. Lydakis, personal communication).
After palletisation is completed, the pallets are moved
either to a fumigation chamber for immediate sulphur
dioxide (SO
2
) treatment, to a forced-air cooler and
fumigation, or to a forced air cooler where fumigation is
done at the end of the day's packing (Figure 9.4a). In any
case, cooling must start as soon as possible and SO
2
applied within 6-12 hours of harvest (see
Diseases and
their control
). After forced air cooling is completed, the
pallets are moved to a storage room to await transport
(Figure 9.4b).
Ideally the storage room operates at −1°C to 0°C (30° to
32°F) and 90 to 95 percent RH, with a moderate air flow
20-40 cubic feet per minute (CFM) per ton stored grapes.
The constant low temperature, high RH and moderate air
flow are important to limit the rate of water loss from fruit
stems. Stores should be regularly monitored for physiolog-
ical deterioration, fruit rot, SO
2
injury, and stem drying.
(b)
(c)
Transportation
Domestic transportation is mainly by refrigerated truck
(Figure 9.4c) but sometimes grapes are transported using
refrigerated rail cars. Exported grapes may be transported
by truck but most are transported by sea freight using cold
stores or containers. When the price is justified, air freight
is used. Throughout transportation, fruit pulp temperatures
should be maintained at −0.5 to 0°C (31-32°F).
Figure 9.4
(a) After palletisation is complete, the
pallets are moved to a fumigation chamber for
immediate SO
2
treatment, to a forced-air cooler or
fumigation or to a forced-air cooler where
fumigation is done at the end of the day's packing.
(b) After cooling is completed, the pallets are moved
to a storage room to await transport. (c) During
transportation, a central loading technique is
utilized to maintain cold temperature during the
transportation period.
Physiological Disorders
Stem, berry browning and water loss
In general, cumulative water loss during post-harvest
handling results in weight loss, fruit stem (rachis or
peduncle and pedicels) browning, berry shatter and even
shrivelling of berries.
