|
|
|
|
 |
 |
|
|
|
|
Green-Seeds.com
Fruits
& Others
|
|
|
Postharvest Handling of Mangoes
The postharvest handling recommendations for mango follow a standard
pattern, although some operations may vary because of varietal differences
and the effects of production on the storage and ripening of the fruit.
Under most circumstances, mangoes can be stored successfully for up to
three weeks if the recommendations concerning harvest maturity, postharvest
handling, and storage conditions are followed.
Quality Criteria
The quality of the fruit on arrival in the importing market is normally
determined by the following criteria:
- Physiologically mature;
- Beginning to ripen, with 30-50 percent yellow coloration;
- Significant area of red color on the fruit shoulders (where applicable);
- Relatively firm;
- Minimum sugar content of 10 percent;
- Free from disease, decay, sunscald, cracks, bruises, latex stains,
and insect and mechanical damage; and
- Conforms to the weight and size specifications.
Varieties
 Successful sales of
mangoes can be achieved only with acceptable stages of ripeness for consumption,
uniform size grading and stages of ripeness, and absence of disease or damage.
In some markets, such as the United Kingdom and the United States, a red
blush typical of the Florida-type varieties is preferred; other markets,
such as France and the Asian population in the United Kingdom, prefer mangoes
that ripen to green to yellow coloration.
There are many varieties
of mango (Mangifera indica L.). Selected varieties in the commercial trade
to Europe, the United States, and Asia include:
Florida type: Tommy Atkins, Haden, Irwin, Zill, Van Dyke, Kent, and Keitt
Haiti: Francisque
North Africa: Amelie
India: Alphonso, Totapuri
Pakistan: Chausa
Kenya: Ngowe, Apple
Australia: Kensington
Thailand: Nan Klarngwun, Nam Dorkmai, Pimsen Daeng, Rad
Philippines: Manila Super (Carabao)
Harvest Maturity
- Harvest maturity in mango plays an important part in both the capacity
required for storage and the overall quality of the fruit when ripe. The
recommended stage of maturity at harvest will depend on the storage time
required and the shipment time; there is, however, a clear distinction between
physiological maturity and commercial maturity. The following categories
are appropriate for the Florida-type varieties and for other varieties that
show similar morphological characteristics:
Fully mature: outgrown
shoulders, formation of a depression with ridges at the stem end, firm,
and green. This fruit has reached physiological maturity. If left on the
tree, it will be ripen naturally; if harvested, it will ripen to excellent
quality.
Half-mature: shoulders in line with the stem with slightly ridged edges,
firm, and green. This fruit has not reached full physiological maturity,
but has reached commercial maturity. If left on the tree, it will develop
to full physiological maturity; if removed from the tree, it will begin
and complete the ripening processes.
Immature: shoulders below the stem insertion with ridges absent, firm,
and green. This fruit is not mature physiologically or commercially. It
will not ripen properly if harvested.
Other characteristics
have been suggested as maturity indices but tend not to be used in commercial
operations because of inconsistency in application. These include the sugar,
acid, and starch content; specific gravity; pulp color; and weight. Mangoes
normally take 80 to 120 days between fruit set and physiological maturity,
depending on the variety, location, and production conditions. Harvesting
after known time intervals is difficult with mango because individual trees
will flower and set fruit over several weeks; the mangoes on one tree are
therefore of differing ages.
Mangoes to be exported
by air should be harvested fully mature‹that is, in the physiologically
mature, hard, green condition. Half-mature fruit may be included in the
shipment, but should not make up more than 25 percent of the total. Fruit
harvested in the ripe condition or with more than 15 percent yellow coloration
should be rejected in the field and not included in export shipments. Ripe
fruit is highly susceptible to bruising and mechanical damage during handling
and transport. Immature fruit should not be shipped.
For mangoes exported
by sea, the optimum stage of harvest maturity is the half-mature stage,
with fully mature fruit being acceptable at the beginning of the harvesting
season. Fruit should not show any signs of softening or degreening (yellow
color development). Immature fruit should not be shipped.
Harvesting 
Because mangoes naturally
set fruit over several weeks, harvesting from each tree has to be selective
and carried out between two and four times over the season. The main considerations
are to ensure the correct maturity and to prevent mechanical damage and
latex staining. Where possible, mangoes should be harvested by hand from
the ground, by snapping them from the stem. Fully mature fruit will detach
easily at the natural abscission point, whereas half-mature fruit will not.
Optimum harvesting involves using shears and cutting the stem 1 to 2 centimeters
away from the fruit; this technique reduces latex exudation and staining
as well as the possibility of fungal organisms entering.
Where harvesting by
hand from the ground is not possible, harvesting implements should be used.
The most suitable involves a long pole with a cutting blade and a small
bag under the blade to catch the fruit. Alternatively, climbers may use
cotton bags that they fill and then lower to the ground. Mangoes should
never be knocked from the tree, dropped, or thrown to the ground. Outgrading
should be carried out in the field to remove immature, undersized, damaged,
bruised, scarred, diseased, and ripe fruit.
After harvest, latex
should be allowed to drain away from the fruit; this is normally carried
out by placing the mango with the stem downward on grass below the tree.
The level of latex flow depends on the maturity of the fruit (younger fruit
normally exudes more latex), time of day (more latex flows in early morning
harvests), and level of rainfall (more latex flows after rainfall). If the
fruit is harvested with a stem, the latex flow is usually minimal and the
fruit can normally be placed directly into a plastic ventilated field crate.
The crate should not contain more than three layers of fruit, and, if possible,
sponge should be used in the base and between the layers to prevent scratching
and bruising. Bags, sacks, and buckets are to be avoided because their use
generally results in mechanical damage and bruising. The fruit in the crate
should be left under the tree until taken to the packhouse. Harvested mangoes
should not be left in direct sunlight, wind, or rain, either in the field
or during transport from the field to the packing facility.
PackHouse Operations
Packhouse facilities
and operations can range from basic operations, with just wash tanks and
grading tables, to highly sophisticated systems with automated washing,
hot water and vapor heat treatment, and size grading. Packhouses used for
export operations normally use wash tanks, roller conveyors, grading tables
or a size grader, and a hot water treatment unit for anthracnose.
On arrival in the packing
area, the mangoes should be re-graded to remove immature, undersized, damaged,
bruised, scarred, or ripe fruit. Acceptable fruit should be placed in a
water tank with 100 parts per million chlorine for washing. If the fruit
was harvested with the stem intact, it should be trimmed at this point to
1 to 2 centimeters. The fruit is wiped with a damp cloth to remove debris
and latex stains, and placed onto grading tables after being separated by
size. Under automated systems, the fruit passes under a spray washer and
onto a moving conveyor belt for size grading.
For mangoes harvested
from areas or trees known to suffer from anthracnose, or for fruit destined
for long-term storage, treatment is required in a hot water bath (50o to
55oC for 3 to 5 minutes, depending on the mango variety). Fungicide treatment,
either separately or included in the hot water bath, also can reduce the
incidence of infection; the fungicide will depend on exporting and importing
country regulations. This technique shows good control of anthracnose; however,
it requires the use of specialized equipment because temperature control
of the water bath is essential for the process to be effective and for prevention
of damage to the fruit.
Mangoes that are to
be exported to markets requiring fruit fly control procedures are treated
after the washing process. The exporter should check the exact requirements
for the operations specified by the importing market, including the treatment,
equipment, and verification. The following are guidelines for different
varieties:
Thailand:
Nan Klarngwun; Vapor Heat Treatment, 46.5oC, 10 minutes
Nam Dorkmai; Vapor Heat Treatment, 46.0oC, 20 minutes
Pimsen Daeng; Vapor Heat Treatment, 46.0oC, 20 minutes
Rad; Vapor Heat Treatment, 46.0oC, 20 minutes
Philippines:
Manila Super (Carabao); Vapor Heat Treatment, 46.0oC, 10 minutes
Taiwan: Irwin; Vapor Heat Treatment, 46.5oC, 30 minutes
Haden; Vapor Heat Treatment, 46.5oC, 30 minutes
After treated with fungicide,
the fruit should be allowed to cool and dry in preparation for grading and
packing.
Some exporting countries
use wax treatments on mangoes to slow the ripening rates during storage
and reduce water loss, and to improve the appearance of the fruit. Products
should be tested for suitability with the relevant varieties and with exporting
and importing country regulations.
Grading
At this point, the fruit
are re-checked to ensure quality specifications have been met before being
separated into groups for packing by count. Fruit should be graded in each
carton according to variety, size by weight or diameter (giving a range
of "counts" for each shipment), and maturity (firm, green full-mature
and half-mature fruit will ripen at different rates and should not be packed
in the same carton). Minimum weight and size specifications for the required
market should be followed. The following counts with the fruit weight (Y´
30 grams) can be used as a guideline for a 4-kilogram carton:
6s: 666 grams 12s: 330 grams
8s: 500 grams 14s: 290 grams
10s: 400 grams 16s: 250 grams
Packing
In most cases, mangoes should be packed with the stem end facing downward
or slightly on one side, rather than directly on the base. This method
does not display the red blush for those markets requiring it. However,
because mangoes normally soften from the base, in long-term storage the
method helps prevent bruising when ripening begins during shipment. Individual
labels can be attached to the fruit for appearance and recognition. Net
weight requirements are 4 to 5 kilograms, depending on the carton and
the market destination. Cartons must not be over- or under-filled during
packing.
Packaging
Mangoes should be packed
in single layer one- or two-piece full-telescopic, self-locking fiberboard
cartons; bursting strength requirements are 250 to 275 pounds per square
inch. Ventilation and handle holes in the sides of the boxes are recommended
to provide adequate ventilation and ease of handling. For sea shipment and
pre-cooling, the cartons should have ventilation in the sides and the top
and bottom; this will allow for horizontal air movement used during forced
air pre-cooling and for vertical air movement used in most modern refrigerated
containers. Carton labeling requirements for the individual markets should
be followed. For air shipment, a layer of shredded paper in the base of
the carton may be used to cushion the fruit; this method is not recommended
for sea ship-ment because it can restrict ven-tilation and harbor fungal
spores. Each alternate mango in a carton should be wrapped in tissue paper
to reduce fruit-to-fruit rubbing. Typical carton external dimensions are
10 by 39.5 by 29.5 centimeters (depth by length by width).
Some countries use modified-atmosphere
packaging with mangoes; the fruit is packed in plastic bags or films, which
can reduce the rate of ripening in storage. Their permeability will produce
varying results, depending on the variety of the fruit, cooling systems
used, and storage temperature. Trials should be carried out and financial
benefits determined before using modified-atmosphere packaging on a commercial
scale.
Unitization
Palletization is essential to min-imize fruit damage from multiple handling.
Movement of fruit within packhouses or during temporary storage can be
aided by palletization. For the export of mangoes by sea, palletization
is necessary. The carton specifications given above are compatible with
the International Standards Organization pallet of 1 meter by 1.2 meters.
Cartons are packed in vertical columns of 18 to 20 levels (depending on
carton depth) with corner boards and strapping to prevent shifting during
transport.
Pre-Cooling
If mangoes are to be
exported to their destination within two to three days of harvesting, as
would be the case if shipped by air, pre-cooling is advisable but not essential.
Mangoes transported by sea should be pre-cooled prior to loading into containers
or holds. Several methods of pre-cooling are available, and the system adopted
should suit specific requirements and capabilities. Temperature-controlled
rooms are the most simple, although cooling may be slow if stacking and
spacing are not adequate to allow free and even air flow or if the refrigeration
capacity is low. Normal cooling time is 24 hours. With the palletized fruit,
a forced-air cooling system is more efficient, and, although this method
requires a specially designed unit and compatible packaging, cooling can
be carried out in 4 to 6 hours. Mangoes should be cooled to a minimum of
10oC. Avoid using refrigerated containers for pre-cooling the fruit because
these are designed to maintain the fruit temperature and not to remove the
field heat.
Storage and Ripening
For export of mangoes
by air, storage or ripening may be required prior to shipment.
Ripening: Recommendations
for the optimum temperature for ripening of mangoes vary according to the
variety and the origin of the fruit, although 20o to 25oC is usually optimum.
Higher temperatures of 25o to 30oC may result in ripe fruit with off-flavors
and mottled peel.Initiation and synchronization of the ripening of mangoes,
and a shortening of their ripening period, can be achieved with exposure
to ethylene gas, either direct from cylinders or as liberated from ethephon
when utilized with a catalytic generator. Acetylene gas liberated from calcium
carbide exhibits a similar effect. Treatments with gases are carried out
in air-tight rooms for 24 hours at 20o to 25oC, 90-95 percent relative humidity.
Gas concentrations required during exposure are 10 to 100 parts per million
(0.00-0.01 percent) for ethylene and 1,000 parts per million (0.1 percent)
for acetylene. Concentrations of gases are controlled by adjusting flow
deliveries or the volume of ethylene delivery liquids (such as ethephon).
Air-tight rooms should have adequate air circulation to enable uniform distribution
of gas throughout the room. Build-up of carbon dioxide is to be avoided
because this reduces the effect of the ethylene and will have a detrimental
effect on fruit ripening. Under optimum conditions, the air should be changed
regularly (once every four hours) and the ethylene re-applied.
Storage: Storage of more than three to five days should not be used for
air-freighted fruit. Prolonged storage should be used only in the case
of sea-freighted exports. At storage temperatures below 10oC, unripe mangoes
will develop chilling injury, which will drastically reduce the quality
of the fruit and increase spoilage. Storage at 10o to 12oC, 85-95 percent
relative humidity, will maintain the fruit in an acceptable condition,
and it will ripen satisfactorily on transfer to higher temperatures. These
criteria depend on the variety of the mangoes, their maturity at harvest,
and the time of harvest in the season. Fully mature mangoes have been
found to show a reduced storage capacity when compared with half-mature
fruit, and this factor becomes more important as the season progresses.
Strict levels of quality
control for fruit stored at low temperatures are essential because blemishes,
bruises, damage, and infections will manifest themselves to a greater degree
than fruit exported by air and marketed rapidly. The potential exists in
stored fruit for high levels of spoilage and poor quality.
Some countries use controlled-atmosphere
refrigerated containers for the long-term storage and shipment of mangoes
(up to four weeks); this method involves maintaining the fruit in a controlled
atmosphere with a high level of carbon dioxide and a low level of oxygen;
recommendations for mangoes are 5 percent carbon dioxide and 5 percent oxygen.
Shipment Conditions
For air shipment, it
is preferable, although not essential, that transport occurs on aircraft
pallets rather than in containers. Shipment in containers may result in
a build-up of heat and ethylene, which will accelerate ripening. For sea
shipment, efficient reefer containers should be used in preference to break-bulk
systems in the ship¹s hold. The stacking systems should be compatible
with the air circulation. Container ventilation should be set at 25-50 percent
open. A temperature recording device should always be included in a carton
when shipping by sea in refrigerated containers.
Potential PostHarvest Losses
Mechanical damage: Mechanically
damaged fruit will deteriorate rapidly and should not be exported. Damaged
regions are susceptible to microbial infection, particularly when low temperature
long-term storage is used. Careful handling should therefore be used during
harvesting and handling operations such as grading, packing, and transportation.
Low temperature: Storage at temperatures below 10oC will result in chilling
injury, including the inhibition of ripening, pitting, internal discoloration,
grey scald-like discoloration of the skin, increased water loss, increased
susceptibility to decay, and detrimental changes in flavor.
Pathological factors: Infection by micro-organisms is generally the most
serious cause of postharvest losses in mango. Disease incidence can be
reduced by good orchard management, pre-harvest cultural practices, appropriate
handling, and postharvest treatment procedures. Washing in static water
tanks will increase the incidence of disease because of the increase in
inoculum from infected fruit; therefore, water has to be changed frequently.
Postharvest applications of specific fungicides will assist in disease
control.
Anthracnose (Colletotrichum
gloeosporioides): Infection occurs in the leaves, stem, young flowers, and
fruit. In the first three, infection results in depressed black circular
or angular lesions; these enlarge and coalesce and affect large areas. Infection
of the fruit is usually latent and manifests itself only as the mango begins
to ripen. Anthracnose is characterized in ripening fruit by small black
circular lesions that gradually enlarge and coalesce as the fruit continues
ripening.
Stem end rot (Diplodia
natalensis) is particularly apparent during low temperature storage. Infection
is characterized by light grey-brown areas in the stem region. Infection
is believed to occur through the cut stem. Disease incidence can be reduced
by leaving 1 centimeter of stem attached to the fruit.
Rhizopus rot (Rhizopus oryzae) develops rapidly at 25oC and is characterized
by skin splitting and course white mold with black spore heads. Infection
takes place after harvest, usually through mechanical injury. The incidence
can be minimized by careful handling, hygienic conditions, and rapid cooling.
Jelly seed is usually found only when the fruit is sliced; affected fruit
show watery translucent tissue around the seed toward the stem-end that
then spreads. The condition is found in harvested fruit but develops as
the fruit ripens. The only means of control at present is early harvesting,
but this may result in the export of immature fruit.
|
|
|
|
|
|
|
|
|
|
|
Green - Seeds Co., Ltd.
81/10B Ho Van Hue Street, Phu Nhuan District, Ward 9, Ho Chi Minh City, Vietnam
Tel: +84 (8) 847 6901 - Fax: +84 (8) 844 1392 - Email: info@green-seeds.com
|
|
|
