Agriculture Reference
In-Depth Information
suppressed greatly in LP-stored fruit as compared to those
stored in normal air. The LPS at 80 mmHg at 10°C for four
weeks also alleviated chilling injury in 'Irwin', 'Kent',
'Keitt', 'Haden' and 'Tommy Atkins' mangoes. A study
conducted in Israel showed that the ripening process was
delayed to 25 and 35 days in fruit stored at 100 and
75 mmHg pressures, respectively, while it was set in control
fruit stored at 760 mmHg after 16 days at 13°C (Apelbaum
et al
. 1977). LPS of mangoes at pressures more than
250 mmHg did not influence ripening process and a marked
reduction in pressure to less than 50 mmHg caused fruit
desiccation. The coloured varieties such as 'Haden' and
'Maya' that had been stored in LP failed to develop their
characteristic fruit colour. The improvement in the storage
life and quality of 'Okrang' mangoes has also been reported
(Ilangantileke & Salokhe 1989) when these were first
hydrocooled to 15°C, dipped in wax and then stored at
13°C either at 60 or 100 mm Hg for four weeks.
Burg (2004, p. 388), in his topic, described some
unpublished reports highlighting the successful application
of LPS in mango. Mango could be stored at very low pres-
sure of 15 mm Hg (= 0.1% O
2
) at 10°C with no indication
of low O
2
injury or off-flavours (Davenport & Burg 2002
unpublished, cited in Burg 2004). The tolerance of mango
to such a low level of O
2
demonstrated the effectiveness of
low pressure in enhancing O
2
diffusion in the fruit. LP
might have improved the mango's gas exchange properties
by opening its stomates (Burg 2004). Similarly, the late
season harvested fully mature 'Keitt' mangoes were stored
at 13.3°C (98%RH) either in normal atmosphere or in LP
at 20 mmHg for 45 days. These fruit ripened with little
increase in decay although they were heavily infected with
anthracnose at the beginning of experiment (Davenport &
Burg 2002 unpublished). Decay development in mango is
a very serious problem paralysing the long-term storage
and distant distribution of mango in the world market and
thus posing a great hindrance in its commercialisation.
These investigations provided evidence in favour of LPS to
overcome this problem and it may prove a big leap if LPS
commercialisation takes place.
& Jayasuriya 2002; Macnish
et al
. 1997; Miller
et al
. 1983;
Pesis
et al
. 2000; Rodov
et al
. 1997; Singh & Janes 2001;
Singh
et al
. 2001; Srinivasa
et al
. 2002; Yuen
et al
. 1993),
it is still not a commercial practice in post-harvest handling
and shipment of mangoes. There is a large range of poly-
meric films available in the market. The selection of a suit-
able packaging film for a cultivar depends upon several
factors such as ripeness stage of fruit, weight and volume,
thickness of film, perforation, permeability to water
vapours, O
2
, CO
2
and C
2
H
4
and temperature conditions in
the supply chain. Individual sealed packaging of 'Tommy
Atkins' mangoes in heat-shrinkable plastic films showed
less weight loss, but the firmness and decay development
were not affected to a large extent compared with
unwrapped fruits (Miller
et al
. 1983). Yuen
et al
. (1993)
observed that shrink wrapping or sealed packaging using
polyethylene, for 'Kensington' mango, caused the undesir-
able retention of green skin colour after 30 days at 20°C.
Shrink wrapping possibly depletes the internal O
2
to such
an extent that there is anaerobiosis in fruit tissue leading to
accumulation of anaerobic metabolites such as ethanol,
acetaldehyde and ethyl acetate which impart strong off-
flavour. Therefore, micro-perforated film could prove more
beneficial for mango packaging, as it prevented the accu-
mulation of high levels of CO
2
that can lead to off-flavours
(Rodov
et al
. 1997). The high decay level and off-flavour
development are major hurdles to commercial acceptance
of individual shrink-wrapping technology for mango.
'Tommy Atkins' and 'Keitt' fruits could be stored for
three weeks at 12°C when these were packed in 4 kg film-
lined cartons by using microperforated polyethylene (PE)
or Xtend
®
film (XF). XF film was found to be very effec-
tive in reducing chilling injury and lowering the level of
condensation inside the package due to lower relative
humidity in the XF film (~ 90%) as compared to PE (~99%)
(Pesis
et al
. 2000). The packaging of 'Karuthacolomban'
mango in 0.05 mm LDPE bags of 1:1 surface area to weight
ratio (cm
2
g
−1
) with 50 ml of saturated potassium permanga-
nate absorbed onto suitable porous matrices and 2 g of
activated granular charcoal could be recommended to
increase storage life at 13°C for 21 days (Illeperuma &
Jayasuriya 2002). The plastic films used for MAP result in
environmental hazards. Today, many environment
protection agencies discourage their use. There is therefore
a quest for alternatives which should be cost-effective,
biodegradable and safe for consumers. The application
of biodegradable films for MAP of fruits is gaining
momentum slowly. 'Alphonso' mangoes stored in
chitosan-covered wax-lined cartons showed an extension
of shelf life of up to 20 days under ambient conditions
Modified atmosphere packaging (MAP)
MAP involves the use of polymeric films to create a
modified atmosphere (MA) that is high in CO
2
and low in
O
2
. The major contributing factors towards the success of
MAP in delaying ripening of mango are increased CO
2
and
low O
2
levels which reduce the respiration rate and inhibit
ethylene biosynthesis, and a plastic film barrier which pre-
vents water loss from fruit. Despite the success of MAP in
mango at laboratory scale (Castro
et al
. 2005; Illeperuma
