Agriculture Reference
In-Depth Information
follows: (1) Mature-green fruit are well developed with a
light green peel; (2) ripening fruit, where harvesting is
commonly done, begin to show colour change on the peel,
from about 25% to 75% yellow, and the glochids begin to
fall off; (3) ripe fruit commonly have 95% to 100% pale
yellow peel colour and are usually soft and can be damaged
easily during and after harvest; and (4) overripe fruit may
show an increasing intensity of the yellow peel colour with
the development of some small rusty-brown discoloured
areas. The fruit has a number of prickles all over, and they
fall off easily on rubbing. There are no special harvesting
techniques; however, it is important that harvesters use
thick rubber or canvas-type gloves to avoid injury from
prickles. Generally, fruit are harvested by twisting the short
peduncle. The fruit is then spread on grassy ground, after
which they are rubbed with gloved hands or with other
means to loosen the prickles. Some harvesting aids have
been tried (Lara-Lopez & Martinez-Yepez 1985).
( Rodriguez-Felix
et al
. 1997).
Nopalea cochenillifera
cladodes lost only 7% water after 12 days storage at 20°C,
and high relative humidity (85-89%) proved to be disad-
vantageous for this species (Nerd
et al
. 1997). Some dis-
colouration due to CI can occur if cladodes are stored
longer than 2 weeks at 5°C (Cantwell
et al
. 1992).
Ascorbic acid content decreased 20-40% after 7 days
storage at 20°C (Rodriguez-Felix
et al
. 1997).
Fruit should be cooled to 5°C to reduce loss of visual
appearance (shiny surface) due to water loss. They are
commonly room-cooled, but may also be forced-air cooled.
Cooling may be delayed if fruit undergo a curing treat-
ment. Fruit can be maintained for 2 to 5 weeks at 5°C to
8°C and 90% to 95% RH, depending on variety, ripeness
stage and harvest season. Factors that limit fruit storage life
include decay, water loss and CI. Attempts to prolong stor-
age life using aqueous wax emulsion coatings did not
result in significant benefits (Estrella-Bolio 1977).
Post-harvest treatments of cactus pears (
Opuntia
ficus-indica
Miller (L.) cv. Gialla) with 1000 mg/L thia-
bendazole (TBZ) at room temperature did not affect the
expression of slight-to-moderate CI, but reduced severe CI
by approximately 50% and decay development by 63.4%
(Schirra
et al
. 2002). The effectiveness of TBZ was much
higher with the treatment at 150 mg/L TBZ at 52°C, pro-
viding 91% control of severe CI and approximately 89%
suppression of decay; with no treatment damage occurred
during storage and simulated marketing period. External
appearance was better in fruit treated with 150 mg/L TBZ
at 52°C. Respiration rate, titratable acidity, soluble solids
contents and acetaldehyde in the flesh were not signifi-
cantly influenced by treatments, but ethylene production
rate and ethanol levels in the flesh were significantly higher
in the TBZ-treated fruit as opposed to those in the untreated
control fruit.
PACKAGING
In Mexico, cladodes are collected in baskets or stacked in
cylindrical packs about 1 metre tall for transport to market,
where they are commonly cleaned by eliminating spines
and vestigial leaves and trimming the sides prior to sale
within 2-3 days. Cladodes produced in the United States or
exported from Mexico are commonly packed in 10 kg
wooden or fibre boxes.
Fruit are commonly packed according to colour, size,
and condition (Piga
et al
. 1996) in ventilated wooden or
plastic crates, 4.5 kg cartons, or in single or double layer
tray cartons. They are also loose packed in 4.5 to 9.0 kg
cartons or boxes. Large fruit may be wrapped in tissue
paper to reduce scuffing and other physical injury. Fruit
may also be packaged in cartons with perforated plastic
liners to reduce water loss under dry storage conditions.
Cooling and storage
Cladodes are cooled to about 5°C to reduce loss of visual
appearance (shiny surface) due to water loss, and to reduce
respiratory weight (and hence weight loss as well as
senescence). They are usually room-cooled, but can also
be forced-air cooled. Hydro-cooling should be avoided as
it favours discolouration in damaged areas, especially
where spines have penetrated the surface, and decay.
Major factors limiting the storage life of cladodes are
decay and dehydration. Cladodes stored under ambient
conditions rapidly lose their brilliant shiny appearance,
become dull-green and may begin to yellow and shrivel
due to water loss. Storage life can reach up to 3 weeks at
5°C and 2 weeks at 10°C when polypropylene foil is used
MODIFIED (MA) AND CONTROLLED
ATMOSPHERE (CA)
Very little work has been done on MA and CA of prickly
pear fruit and cladodes, but holding at 5°C in 2% O
2
+ 2 to
5% CO
2
can delay ripening and senescence and extend
storage life of fruit and cladodes. Packaging cladodes in
Cryovac PD960 films created a MA as a result of the high
respiration rate of the cactus stems, where oxygen
decreased to about 8.6% and CO
2
increased to about 6.9%
after 30 days in storage (Guevara
et al
. 2001; 2003).
Cladodes packaged in MA had very low weight loss
(Figure 13.3).
The texture and crude fibre contents of cladodes that
were maintained in MA packages (MAP) decreased only
