|
|
|
|
 |
 |
|
|
|
|
Green-Seeds.com
Fruits
& Others
|
|
|
Postharvest Handling of Durians
Durians (Durio zibethinus J. Murr.) are one of the most highly valued
and desired fruits among Southeast Asians and are well known for excellent
flavor and unique, sometimes offensive, odor. Although postharvest handling
operations for durians are relatively simple, the fruits ripen quickly
after harvest, and high postharvest losses are possible. Harvesting at
the proper stage of maturity, preventing mechanical damage, cooling, and
maintaining correct temperature can allow a storage and shelf life of
five to seven days.
Quality Criteria
Quality criteria for durians vary among consumer groups, based on the
fruits¹ ripeness. Some consumers prefer fully ripe fruits with no
splitting, whereas others prefer less ripe fruits with relatively firm
texture and a milder aroma. In all cases, the seeds must separate easily
from the pulp; the best varieties have small seeds and large arils (pulp).
Varieties
 Acceptable varieties
of durian are those that meet the market quality criteria, including aril
volume, texture, and flavor, and, for the grower, yields, spread of harvest,
and shelf life. Durians are genetically diverse in terms of fruit size,
shape, skin color and thickness, aril volume, color, aroma, texture, flavor,
seed number and size, and peduncle length. The varieties showing the best
production, fruit quality, and seasonal range in various countries are as
follows:
€ Malaysia‹D2 (Dato Nina), D10 (Durian Hijau), D16, D24, D98
(Katoi), D116 (Batu), D117 (Gombak), D123 (Rim 2), and Hew 3;
€ Thailand‹Gaanyao, Montong, Kob Picul, Chanee, Luang, Kradoom
Tong, and Chompoosri; and € Indonesia‹Sitokong, Bakul, Mas,
Sitebel, Simanalagi, and Simadat.
€ Indonesia‹Sitokong, Bakul, Mas, Sitebel, Simanalagi, and
Simadat.
Durians are round to
oblong with an average length of 20 centimeters and a width of 15 centimeters,
although fruits from some Thai cultivars may be up to 40 centimeters long.
Individual fruits average 2.4 kilograms, but may exceed 3 kilograms. When
ripe, the fruits split from the apex into three to five irregular segments
(arils), each of which contains one to seven seeds.
Durian seeds are large,
at 4 to 7 centimeters long and 2.5 centimeters wide. On average, an entire
durian contains 13 seeds. The edible pulp covers each seed, and varies among
cultivars in terms of color, texture, and thickness. It is yellowish white,
pale yellow, or orange; buttery; sweet; and very aromatic.
The skin of the durian
is green to yellowish brown, strong, and thick, with sharp, pointed, pyramidal
spines. The fruit¹s peduncle measures 1 to 1.2 centimeters thick and
5 to 6 centimeters long.
Harvest Maturity 
The growth of the durian fruit follows a sigmoid curve; growth is very
fast until the 13th week after pollination, after which it slows until
the 16th week (112 days), when the fruit reaches maturity and falls from
the tree. The fruit normally ripens two to three days after it falls.
A fruit harvested from the tree is cut 15 weeks after anthesis Y´
3 days (105 days). The skin of the durian shows little color change during
ripening; as a result, ripeness is judged by changes in the fruit¹s
smell or the hollow sound produced when its spines are tapped.
Harvesting
Durian trees that are
asexually propagated normally bear fruit 5 to 7 years after planting, whereas
seedling trees may take 8 to 10 years. Trees may produce as few as 10 fruits
or as many as 500 in a season. Fruits should be detached from the tree with
the peduncle intact before theyreach full maturity, but at a stage late
enough to ensure normal ripening without loss of flavor. Fruits harvested
in this way may have a shelf life of up to seven days.
Durian fruits are also
collected daily from the ground after they naturally abscise from the tree.
In most cases, the fallen fruits sustain damage, which speeds up deterioration
and forces rapid marketing, as fermentation begins as soon as the fruits
drop from the tree. Unbroken durians may remain edible for two to three
days.
Packhouse Operations
For grading and packing
durians, simple operations are sufficient. These include trimming the stem,
classifying to remove damaged or split fruits, cleaning or brushing, packing,
precooling (sometimes), storing, and transporting.
Durian fruits are not
normally size-graded once they meet the minimum size requirement. Packing
varies depending on the fruits' origin, but most durians are packed in single
layers in telescopic cartons with the pedicel pointing up. Fruits should
not be forced into the carton, because force may cause mechanical damage.
Carton net weights range from 18.2 to 22.7 kilograms with between three
and five fruits per carton.
Postharvest fungicide
treatment with fosetyl aluminum at 4 grams per liter of water for two minutes
is reported to control Phytophthora palmivora; however, exporting- and importing-country
regulations for pesticide use should be consulted before the treatment¹s
use. Wrapping the peduncle with banana leaf or paper reportedly extends
shelf life. Studies indicate that waxes can be used to increase storage
life by reducing water loss, delaying splitting, and slowing the ripening
process. Gibberellic acid treatments may also reduce ripening rates.
Packaging
Packaging is in two-piece
telescopic cartons with a minimum breaking force of 275 pounds per square
inch. Ventilation is required in all four side walls. Narrow, vertical ventilation
is preferred, because round vent holes will become blocked by the fruits.
Carton dimensions vary
depending on the net weight and the market, with the most common pack of
18.2 kilograms having the following external dimensions, which are compatible
with ISO pallets: 40 centimeters long by 30 centimeters wide by 38 centimeters
high.
Packages should have
all the labeling information required by the importing country, which may
include the following:
€ Country of origin;
€ Product/variety;
€ Net weight/count; and
€ Exporter name/importer name.
Cooling and Storage
Durians can be stored for up to three weeks at temperatures of 15oC.
However, some reports state that 4oC to 5oC can be used for two to three
weeks. Ethylene treatment or presence can increase the ripening rate and
advance splitting. Reports also indicate ripening can be stimulated in
durians harvested between 70 percent and 80 percent maturity by dipping
the fruits in an ethephon solution before they are transported to market.
Transportation
Because of durians¹
high perishability, exports are made by air. Transport from the packing
facility to the airport should be in cool trucks if the fruits have been
cooled. In all cases, trucks should be covered to prevent contact with wind,
rain, and sun.
Because durians emit
a notable odor to which most airlines would object, the fruits are shipped
in aircraft containers rather than aircraft pallets. Heat build-up inside
the containers can occur, especially if they are left exposed to the sun
while awaiting loading in the airport. This is obviously detrimental to
the fruits; attempts should be made to ensure that the aircraft containers
are held in shady or cool locations until loading.
Potential Post-harvest Problems
Phytophthora infection
produces brown patches that turn black under wet conditions and form a whitish
bloom from the cottony mycelia. The rot can extend internally from the durian
skin toward the seeds. The fungus can attack the fruits while they are attached
to the tree or after they have fallen to the ground. Pre-harvest sprays
may help control the fungus, but because of difficulties with application,
additional measures‹removing debris from around the trees and planting
plants nearby that are known to repel vectors such as crawling insects and
snails‹are advisable.
Other fungi can infect
the fallen fruits as secondary infections through the bruised skin after
the fruits hit the ground. Infection rates are high in fruits that are left
on the ground uncollected for several days, particularly if the ground is
wet. Diseases that can befall the fruits include Rhizopus, Mucor, and Lasiodiplodia,
which produce soft rots and necrosis that can spread to the arils. Others
diseases that do not cause softening and are superficial include Phyllosticta,
Colletotrichum, and Curvulari. Another, Fusarium, produces water-soaked,
soft, and pulpy lesions. One can control these diseases by collecting fruits
frequently, brushing off debris such as leaves and soil, or constructing
catching nets. Fungicide treatments for these diseases normally are ineffective
because the diseases are secondary and infect the fruits through damaged
areas.
Additional Information
Coronel, R. E. 1986. Promising Fruits of the Philippines. Durian: pp.
161-182. Los Baños, Philippines: College of Agriculture, University
of the Philippines at Los Baños.
Ketsa, S., and S. Pangkool. 1995. ³The Effect of Temperature and
Humidity on the Ripening of Durian Fruits.² Journal of Horticultural
Science. 70(5): 827-831.
‹‹‹. 1995. ³Ripening Behavior of Durians (Durio zibethinus
Murray) at Different Temperatures.² Tropical Agriculture (Trinidad).
72(2): 141-145.
Kwee, L. T. 1990. Durian: Disease and Disorders. Kuala Lumpur, Malaysia:
Tropical Press. SDN. BHD. Page, P. E. 1984. Tropical Tree Fruits for Australia.
Durian: pp. 45-50. Brisbane, Australia: Queensland Department of Primary
Industries.
Sriyook, S., S. Siriatiwat, and T. Siriphanich. 1994. ³Durian Fruit
Dehiscence‹Water Stress and Ethylene.² HortScience. 29(10):
1,195-1,198.
|
|
|
|
|
|
|
|
|
|
|
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
|
|
|
