The keluak (scientific name Pangium edule) is a tall tree found in South East Asia and Oceania. It grows in the swamps of mangroves in Malaysia, Indonesia and Papua New Guinea. Its fruit, known as the "football fruit" due to its size, is normally poisonous but fermentation makes it edible.
The keluak tree is a perennial evergreen species, with a large number of branches, and usually reaches a height between 18 and 40 m. It favors soils that are mildly acidic and locations with partial shade from larger trees or objects. It can also grow on grounds with clay or stones and it usually inhabits swamps, inundated zones and riverbanks. It has a big trunk that can even reach the diameter of 1 m, covered with bark of a grey or brown color and young trees grow very fast.
Keluak leaves consist of 3 lobes in young specimens but become entire and broadly ovate later. They have a length between 15 and 25 cm, with either a truncate or cordate base. The keluak leaves are green with a glossy finish and have palmate nerves. Flowers are either male or female, similar in appearance. The difference is that male ones are grouped in racemes, while female flowers tend to grow isolated. Male flowers have a size of about 5 cm and consist of 5 or 6 petals, 2 or 3 calyx lobes and numerous stamens. Female ones don't have stamens at all but an equal number of staminoids that alternate with the petals. They have between 2 and 4 placentae, with ovules and sessile stigma and thick walls.
Keluak fruits are similar to a football in both shape and size. They grow to a large dimension of about 15 to 30 cm in length and 7 to 15 cm wide, with the typical football shape. Keluak fruits are covered in brown rough skin, which doesn't open to release seeds. Under the first rough layer of skin there is a white or pale yellow rind with a thickness of around one inch. The skin is very strong and allows the fruit to fall from 30 feet or more without any damage when it hits the ground. Inside the rind there is yellow flesh surrounding a few large seeds.
The keluak seeds have a length of about two inches and a gray or brown color, with a flat profile. Keluaks are considered to be ripe as soon as their rough skin turns soft when touched. The flesh has a strong taste and smell, sometimes compared to a durian.
Seeds, fruits, bark, leaves.
The keluak tree has several medical uses, depending on the region. Every part of it is known for its anthelmintic properties in the Philippines, while in Malaya the fresh seeds are crushed then applied to boils in order to cure them. The keluak fruit is a major source of copper, an essential mineral required for a healthy life and growth. Eating keluak fruits is one of the easiest way to get the needed amount of copper in your daily diet, since the mineral is vital for a healthy nervous, bone and cardiovascular system. People who don't supply enough copper to their body have a low amount of blood cells, which prevent the oxygenation of tissues.
Keluaks are also rich in vitamin C, a powerful antioxidant that prevents gout. Gout is a very painful condition, with similar symptoms to arthritis. It usually starts in the big toe. A lack of vitamin C leads to high levels of uric acid in the blood, which deposits in the joints in the form of crystals. The toe gets swollen and stiff, with severe pain. Eating keluak fruit provides enough vitamin C to prevent gout.
Another essential mineral found in high amounts in the fruit is iron. This mineral is a key component in several essential systems of the body, such as the immune system. With a proper supply of iron, the immune system is able to resist infections and stop numerous diseases. Iron is also the main building block of red blood cells, used to transport oxygen to every organ and tissue in the body. Without enough iron we can't produce enough hemoglobin so oxygen doesn't reach the cells in the required amounts and healing is disrupted.
Like many fruits, the keluak is also a major source of dietary fibers. These nutrients are considered to be more and more important by scientists, since they can soften the stool while at the same time making it bulkier and heavier. This prevents constipation because the stool travels faster through the system. Fibers absorb water and boost stool size, turning liquid stools into solid ones. This is why fruits are recommended in every healthy modern diet.
The next important mineral provided by the keluak fruit is magnesium. It plays many key roles in our metabolism and is especially known to reduce the risk of heart diseases, with a proper supply making a stroke a lot less likely. In addition, the heart has an irregular rhythm without magnesium, worsening the aftermath of any heart attacks. For this reason, nutritionists advise us to make sure that we get the required amount of magnesium every day, either from food or from dietary supplements.
Premenstrual syndrome (PMS) is a common problem for many women today and it has numerous symptoms. Keluak fruits have a content of manganese, which can counter most of these negative effects such as depression, irritability, headaches as well as mood swings. While manganese can be provided today from dietary supplements, it is healthier to get it from natural sources like the keluak.
The plant is rich in glucosides, which have a number of medical uses despite being toxic compounds. They are the reason why the crushed fresh seeds can be applied on wounds to disinfect them, since they have the power to kill pathogens. They can also be applied on boils as a poultice, due to the same effect. Leaves have antiseptic properties as well and can be applied externally to clean wounds and eliminate parasites. An old remedy against head lice is to heat the leaves then use a cloth to place them on the scalp. The fruit juice is antiseptic as well and can replace the other parts of the plant to clear wounds and sores.
The bark of mature trees has been used to prepare a product that is said to improve the quality of breast milk and make infants grow stronger and resist diseases. For this purpose, the bark must be crushed then turned into a soup and consumed by lactating females. It is also possible to place the inner bark on a hot stone and to inhale the resulting fumes, as a cure for inflamed joints.
The keluak tree also has some industrial uses. The oil can be transformed into soap or burned to create light. Since it is toxic, it is used in the Camarines to poison fish. The toxic seeds are sometimes included in pieces of roasted coconut in order to kill wild birds and rats.
Both the fresh fruit and its seeds have a content of hydrogen cyanide and eating them raw can have lethal consequences. The seeds require a lengthy preparation before they can be consumed. They have to be boiled and then buried in a mix of ash, earth and banana leaves for a minimum of 40 days. Fermentation turns their initial white color into brown or black, they can be washed and eaten. By that time, the hydrogen cyanide is soluble in water and can be rinsed away.
"Sayor lodeh" is a spicy side dish traditional in Indonesian cuisine that is prepared from the immature seeds. After they are ripe, the seeds are turned into "keluwak", an ingredient with a special bitter flavour that is included in condiments, soups and other dishes. The seeds have to be first fermented in pits.
The seeds can also be pressed to produce an oil that can replace coconut oil for cooking. It is considered to be a quality ingredient and a safe one as well, since heating eliminates all toxins. However, it must be consumed fast, before it becomes rancid due to the high olein content.
In some areas of the Philippines the pulp is eaten as well. However, it also contains some toxins that can cause severe headaches. The kernel is poisonous as well but roasting removes the threat and it becomes edible.
It is possible to simply eat the flesh uncooked but it can also be prepared as a jam or into a product similar to apple butter. The recipe is simple: boil the flesh until it becomes a jam, then add coconut milk into the mix and simmer the composition for a while. This process can preserve the flesh for several months.
Gynocardine, a cyanogenetic glycoside exactly like the one in Gynocardia odorata, has been identified in the leaves. The kernel is rich in oils such as oleic and palmitic types, as well as hydnocarpic or chaulmoogric oils, which are optically active.
Due to their content of toxic and bioactive compounds, all parts of the plant including the fruits are known to be narcotic. Larger amounts can cause headaches, dizziness and in severe cases delirium or even death.