Durio graveolens

Durio graveolens

The red-fleshed durian or orange-fleshed durian or yellow durian, (Durio graveolens Becc., 1889) is an arboreal species belonging to the Bombacaceae family.

Systematics –
From a systematic point of view it belongs to:
Eukaryota domain,
Kingdom Plantae,
Magnoliophyta division,
Class Magnoliopsida,
Subclass Dilleniidae,
Malvales Order,
Bombacaceae family,
Genus Durio,
D. graveolens species.

Etymology –
The term Durio comes from durian (or durion) which is the Malay vernacular name for the thorny fruit of this plant, where duri means thorn.
The specific epithet graveolens derives from the Latin « gravis » (heavy, strong) and « olens » (smell), as the fruit has a strong smell.

Geographic Distribution and Habitat –
Durio graveolens is a plant native to Southeast Asia that grows in Peninsular Malaysia (states of Johor, Kedah, Kelantan, Malacca, Penang, Perak, Selangor and Terengganu), Borneo, Sumatra, Palawan and southern Thailand.
This plant is grown in the following territories: Brunei, Sarawak, Sabah, and in Northern Australia.
In Brunei, its popularity surpasses D. zibethinus, which is not cultivated in the country.
It is also occasionally grown outside the tropics.
Its natural habitat is lowland forest, often on clay-rich soils in mixed Dipterocarpus forests and on schist ridges, at altitudes up to 1,300 metres.

Description –
Durio graveolens is a tree that can grow up to 40 meters in height with a smooth to scaly, grey/mauve to reddish brown trunk, 85–100 cm in diameter, with steep roots forming buttresses. The buttresses reach 3m and extend 1.5m.
The leaves are oblong in shape, are 10–26 cm long and 4–10 cm wide. These are perfectly rounded on both ends, stiff and slightly leathery (both to the touch and in texture). In the upper part they are hairless and crunchy, as if they were varnished. On the underside they are copper-brown and scaly, with large scales up to 2 mm in diameter, which are not very evident, at least when dry. The leaf scales are peltate (shield-shaped), radiate from ciliate (fringed), and deeply lobed in three to five parts. In addition to the scales, long strands of stellate hairs and other trichomes of various sizes form a soft tomentose surface. The midrib of the leaf is very prominent on the underside and forms a crease on the top. Leaf stipules are deciduous (fall off early). The leaves have 10-12 lateral veins per side (with some smaller ones interspersed), which are tiny and shallow above and more distinct, but still barely visible. The petiole is very large, 15–18 mm long, and tumescent (swollen) from center to top.
The flowers grow on the branches on short colas and a thin calyx. The base is bag-shaped with three to five connate lobes. They have white, spatulate (spoon-shaped) petals 25-35 millimeters long. Inside are five separate bundles of staminodes and stamens, fused for less than half their length. The anther has small clusters of four or five elongated pollen loculi which open with longitudinal slits. The ovaries are ovoid to globose (roughly spherical) and possess a yellow capitate stigma (pinhead shaped) and a white to greenish style about 48 mm in length.
The pollen is psilated (relatively smooth), spheroidal and 54 μm in diameter. The pollen surface comprises three colporate openings, meaning that the openings have a combined hit (or groove) and pore. Pollen grains do not clump together.
The fruits have a diameter of up to 10–15 cm and weigh around 700 grams. The exterior is greenish to yellow-orange in color and is densely covered with 1 cm long and thin angular subulate spines; they are straight or slightly curved and prickly but slightly soft.
The fruit breaks easily into five fibrous-coriaceous shells (sections) with walls 5–6 millimeters thick. The fruit typically opens on the tree, but some varieties don’t until they are dropped to the ground or picked. For each section there are 2 bulbous or chestnut-shaped seeds, each completely enveloped in a fleshy aril.
These shiny brown seeds measure 2 cm × 4 cm. The pungent aril is the part eaten as food, although some sources note that the odor is sometimes very mild. The color varies from light yellow to orange to bright red.

Cultivation –
Durio graveolens is similar to Durio dulcis, but differs in the color of the fruit.
The fruit is edible and is mostly harvested from the wild, although the tree is also occasionally cultivated.
It is a tree that grows in humid tropical areas and is found at altitudes up to 1,300 meters and also on slopes.
It often grows naturally on clay-rich soils. Seed-propagated trees can begin flowering when they are only 6 years old.
In order to grow well, this plant needs high temperature and humidity values.
Due to its tolerance for moist habitats, it is probably resistant to infection by the oomycete Phytophthora palmivora.
The flowers are pollinated by bats. As it is one of the few species to hybridize naturally with D. zibethinus, it is thought that they share a pollinator, probably the bat Eonycteris spelaea. Pollen from both of these durian species has been found in the feces of cave nectar bats, and possibly in those of the bat Macroglossus sobrinus.
After harvesting, the fruits can be attacked by fungi such as Lasiodiplodia theobromae, Glomerella cingulata, Geotrichum candidum, Calonectria kyotensis and occasionally Gliocephalotrichum bulbilium. A secondary or opportunistic fungal infection can come from species such as Aspergillus niger and other Aspergillus spp., Candida spp., Gibberella intricans and Penicillium spp.
Propagation is mainly by seed.

Customs and Traditions –
Durio graveolens is one of six species of Durian named by the Italian naturalist Odoardo Beccari.
It is an edible plant and perhaps the most popular “wild” species of durian; it is sold commercially regionally. However, its congener Durio zibethinus is the best known and most eaten species worldwide.
As far as edible uses are concerned, remember that the pulp of the fruit is sweet and is eaten raw and has a very sweet taste.
The aril around the seed is edible but not very juicy, not very fragrant and not very tasty. Unlike many other durian, aril is odorless.
The fruit is often used for seasoning and is used in soups.
According to some, the pulp of the fruit has the scent of toasted almonds or burnt caramel. The taste is described as sweet and cheesy or similar to that of an avocado or peppery cheese.
Sometimes, it is fermented in tempoyak seasoning. The red-fleshed varieties are used with freshwater fish to make a type of sayur (a traditional Indonesian vegetable stew).
The seeds can also be ground into flour (dalit tepung biji durian), which can then be used to make, for example, fish crackers.
From a biochemical point of view, the following is an average composition:
– the fatty acids in fruit are 30% saturated and 70% unsaturated. Saturated fats include myristic acid (14.49%), arachidic acid (7.08%), pentadecanoic acid (3.61%), heptadecanoic acid (2.2%), decanoic acid (1.62%) and lauric (1.31%). Unsaturated fats include oleic acid (22.18%), palmitoleic acid (13.55%), linolelaidic acid (12.39%), γ-linolenic acid (12.23%), linoleic acid (4.95%) , elaidic acid (2.50%) and myristoleic acid (1.89%).
Among other uses it should be noted that the wood is relatively resistant and is used in interior construction and to make cheaper types of furniture and packing cases.
Heartwood is pink-brown, red, or deep red-brown; it is not always sharply demarcated from the white, pale yellow-brown, or pale reddish-yellow sapwood. The texture is coarse; straight to intertwined grain; somewhat bright; it is said to have a fetid smell. Wood is not durable and does not resist attack by termites; the sapwood is subject to attack by dust beetles. It dries quickly, but thin panels may tend to warp. The wood cuts easily and generally dresses softly; the nailing qualities are good. It is used for purposes such as furniture components, veneer and plywood, light construction.
From an ecological point of view, it should be emphasized that the fruits of this plant are food for many animals. These include Bornean orangutans (Pongo pygmaeus), Prevost’s squirrels (Callosciurus prevostii), crab-eating macaques (Macaca fascicularis), black hornbills (Anthracoceros malayanus), possibly viverrids and bears of the species Helarctos malayanus. Black hornbills are also effective seed dispersers for the tree; therefore it is indicated in some of the regional names of the tree.
It is also reported that the IUCN Red List classifies Durio graveolens as a vulnerable species.

Method of Preparation –
Durio graveolens is a plant whose fruits are consumed, whose pulp is sweet and is eaten raw.
Even the aril around the seed is edible but not very juicy, not very fragrant and not very tasty and odorless.
The fruit is also often used for seasoning and in soups.
Sometimes, it is fermented in tempoyak seasoning. The red-fleshed varieties are used with freshwater fish to make a type of sayur.
The seeds can be ground into flour (tepung biji durian dalit) and used in various ways.
The tree is also harvested for timber in Sarawak. The Iban also bathe day-old infants (especially for early births) in an herbal tea made from the mature bark, as they believe it strengthens the skin.

Guido Bissanti

Sources
– Acta Plantarum – Flora of the Italian Regions.
– Wikipedia, the free encyclopedia.
– GBIF, the Global Biodiversity Information Facility.
– Useful Tropical Plants Database.
– Conti F., Abbate G., Alessandrini A., Blasi C. (ed.), 2005. An annotated checklist of the Italian vascular flora, Palombi Editore.
– Pignatti S., 1982. Flora of Italy, Edagricole, Bologna.
– Treben M., 2000. Health from the Lord’s Pharmacy, Advice and experiences with medicinal herbs, Ennsthaler Editore.

Attention: The pharmaceutical applications and alimurgical uses are indicated for informational purposes only, they do not in any way represent a medical prescription; we therefore decline all responsibility for their use for curative, aesthetic or food purposes.