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Morton, J. 1987. Bael Fruit. p. 187–190. In: Fruits of warm climates. Julia F. Morton, Miami, FL.


Bael Fruit

Aegle marmelos Correa

syn. Feronia pellucida Roth, Crataeva marmelos L.




Though more prized for its medicinal virtues than its edible quality, this interesting member of the family Rutaceae is, nevertheless, of sufficient importance as an edible fruit to be included here. The bael fruit, Aegle marmelos Correa (syns. Feronia pellucida Roth., Crataeva marmelos L.), is also called Bengal quince, Indian quince, golden apple, holy fruit, stone apple, bel, bela, sirphal, maredoo and other dialectal names in India; matum and mapin in Thailand; phneou or pnoi in Cambodia; bau nau in Vietnam; bilak, or maja pahit in Malaya; modjo in Java; oranger du Malabar in French; marmelos in Portuguese. Sometimes it is called elephant apple, which causes confusion with a related fruit of that name, Feronia limonia Swingle (q.v.).

A hard-shelled bael fruit
Fig. 47: A hard-shelled bael fruit (Aegle marmelos), of the type valued more for medicinal purposes than for eating.

Description

The bael fruit tree is slow-growing, of medium size, up to 40 or 50 ft (12-15 m) tall with short trunk, thick, soft, flaking bark, and spreading, sometimes spiny branches, the lower ones drooping. Young suckers bear many stiff, straight spines. A clear, gummy sap, resembling gum arabic, exudes from wounded branches and hangs down in long strands, becoming gradually solid. It is sweet at first taste and then irritating to the throat. The deciduous, alternate leaves, borne singly or in 2's or 3's, are composed of 3 to 5 oval, pointed, shallowly toothed leaflets, 1 1/2 to 4 in (4-10 cm) long, 3/4 to 2 in (2-5 cm) wide, the terminal one with a long petiole. New foliage is glossy and pinkish-maroon. Mature leaves emit a disagreeable odor when bruised. Fragrant flowers, in clusters of 4 to 7 along the young branchlets, have 4 recurved, fleshy petals, green outside, yellowish inside, and 50 or more greenish-yellow stamens. The fruit, round, pyriform, oval, or oblong, 2 to 8 in (5-20 cm) in diameter, may have a thin, hard, woody shell or a more or less soft rind, gray-green until the fruit is fully ripe, when it turns yellowish. It is dotted with aromatic, minute oil glands. Inside, there is a hard central core and 8 to 20 faintly defined triangular segments, with thin, dark-orange walls, filled with aromatic, pale-orange, pasty, sweet, resinous, more or less astringent, pulp. Embedded in the pulp are 10 to 15 seeds, flattened-oblong, about 3/8 in (1 cm) long, bearing woolly hairs and each enclosed in a sac of adhesive, transparent mucilage that solidifies on drying.

Origin and Distribution

The tree grows wild in dry forests on hills and plains of central and southern India and Burma, Pakistan and Bangladesh, also in mixed deciduous and dry dipterocarp forests of former French Indochina. Mention has been found in writings dating back to 800 B.C. It is cultivated throughout India, mainly in temple gardens, because of its status as a sacred tree; also in Ceylon and northern Malaya, the drier areas of Java, and to a limited extent on northern Luzon in the Philippine Islands where it first fruited in 1914. It is grown in some Egyptian gardens, and in Surinam and Trinidad. Seeds were sent from Lahore to Dr. Walter T. Swingle in 1909 (P.I. No. 24450). Specimens have been maintained in citrus collections in Florida and in agriculture research stations but the tree has never been grown for its fruit in this state except by Dr. David Fairchild at his home, the "Kampong", in Coconut Grove, after he acquired a taste for it, served with jaggery (palm sugar), in Ceylon.

Climate

The bael fruit tree is a subtropical species. In the Punjab, it grows up to an altitude of 4,000 ft (1,200 m) where the temperature rises to 120º F (48.89º C) in the shade in summer and descends to 20º F (-6.67º C) in the winter, and prolonged droughts occur. It will not fruit where there is no long, dry season, as in southern Malaya.

Soil

The bael fruit is said to do best on rich, well-drained soil, but it has grown well and fruited on the oolitic limestone of southern Florida. According to L. B. Singh (1961), it "grows well in swampy, alkaline or stony soils". . . "grows luxuriantly in the soils having pH range from 5 to 8". In India it has the reputation of thriving where other fruit trees cannot survive.

Varieties

One esteemed, large cultivar with thin rind and few seeds is known as 'Kaghzi'. Dr. L.B. Singh and co-workers at the Horticultural Research Institute, Saharanpur, India, surveyed bael fruit trees in Uttar Padesh, screened about 100 seedlings, selected as the most promising for commercial planting: 'Mitzapuri', 'Darogaji', 'Ojha', 'Rampuri', 'Azamati', 'Khamaria'. Rated the best was 'Mitzapuri', with very thin rind, breakable with slight pressure of the thumb, pulp of fine texture, free of gum, of excellent flavor, and containing few seeds.

S.K. Roy, in 1975, reported on the extreme variability of 24 cultivars collected in Agra, Calcutta, Delhi and Varanasi. He decided that selections should be made for high sugar content and low levels of mucilage, tannin and other phenolics.

Only the small, hard-shelled type is known in Florida and this has to be sawed open, cracked with a hammer, or flung forcefully against a rock. Fruits of this type are standard for medicinal uses rather than for consuming as normal food.

Propagation

The bael fruit is commonly grown from seed in nurseries and transplanted into the field. Seedlings show great variation in form, size, texture of rind, quantity and quality of pulp and number of seeds. The flavor ranges from disagreeable to pleasant. Therefore, superior types must be multiplied vegetatively. L.B. Singh achieved 80% to 95% success in 1954 when he budded 1-month-old shoots onto 2-year-old seedling bael rootstocks in the month of June. Experimental shield-budding onto related species of Afraegle and onto Swinglea glutinosa Merr. has been successful. Occasionally, air-layers or root cuttings have been used for propagation.

Culture

The tree has no exacting cultural requirements, doing well with a minimum of fertilizer and irrigation. The spacing in orchards is 25 to 30 ft (6-9 m) between trees. Seedlings begin to bear in 6 to 7 years, vegetatively propagated trees in 5 years. Full production is reached in 15 years. In India flowering occurs in April and May soon after the new leaves appear and the fruit ripens in 10 to 11 months from bloom–March to June of the following year.

Harvesting

Normally, the fruit is harvested when yellowish-green and kept for 8 days while it loses its green tint. Then the stem readily separates from the fruit. The fruits can be harvested in January (2 to 3 months before full maturity) and ripened artificially in 18 to 24 days by treatment with 1,000 to 1,500 ppm ethrel (2-chloroethane phosphonic acid) and storage at 86º F (30º C). Care is needed in harvesting and handling to avoid causing cracks in the rind.

A tree may yield as many as 800 fruits in a season but an average crop is 150 to 200, or, in the better cultivars, up to 400.

Keeping Quality

Normally-harvested bael fruits can be held for 2 weeks at 86º F (30º C), 4 months at 48.2º F (9º C). Thereafter, mold is likely to develop at the stem-end and any crack in the rind.

Pests and Diseases

The bael fruit seems to be relatively free from pests and diseases except for the fungi causing deterioration in storage.

Food Uses

Bael fruits may be cut in half, or the soft types broken open, and the pulp, dressed with palm sugar, eaten for breakfast, as is a common practice in Indonesia. The pulp is often processed as nectar or "squash" (diluted nectar). A popular drink (called "sherbet" in India) is made by beating the seeded pulp together with milk and sugar. A beverage is also made by combining bael fruit pulp with that of tamarind. These drinks are consumed perhaps less as food or refreshment than for their medicinal effects.

Mature but still unripe fruits are made into jam, with the addition of citric acid. The pulp is also converted into marmalade or sirup, likewise for both food and therapeutic use, the marmalade being eaten at breakfast by those convalescing from diarrhea and dysentery. A firm jelly is made from the pulp alone, or, better still, combined with guava to modify the astringent flavor. The pulp is also pickled.

Bael pulp is steeped in water, strained, preserved with 350 ppm S02, blended with 30% sugar, then dehydrated for 15 hrs at 120º F (48.89º C) and pulverized. The powder is enriched with 66 mg per 100 g ascorbic acid and can be stored for 3 months for use in making cold drinks ("squashes"). A confection, bael fruit toffee, is prepared by combining the pulp with sugar, glucose, skim milk powder and hydrogenated fat. Indian food technologists view the prospects for expanded bael fruit processing as highly promising.

The young leaves and shoots are eaten as a vegetable in Thailand and used to season food in Indonesia. They are said to reduce the appetite. An infusion of the flowers is a cooling drink.

Food Value Per 100 g of Edible Portion*

Water 54.96-61.5 g
Protein 1.8-2.62 g
Fat 0.2-0.39 g
Carbohydrates 28.11-31.8 g
Ash 1.04-1.7 g
Carotene 55 mg
Thiamine 0.13 mg
Riboflavin 1.19 mg
Niacin 1.1 mg
Ascorbic Acid 8-60 mg
Tartaric Acid 2.11 mg
*Fresh bael fruit, as analyzed in India and in the Philippines.

The pulp also contains a balsam-like substance, and 2 furocoumarins-psoralen and marmelosin (C13H12O3), highest in the pulp of the large, cultivated forms.

There is as much as 9% tannin in the pulp of wild fruits, less in the cultivated types. The rind contains up to 20%. Tannin is also present in the leaves, as is skimmianine.

The essential oil of the leaves contains d-limonene, 56% a-d-phellandrene, cineol, citronellal, citral; 17% p-cyrnene, 5% cumin aldehyde. The leaves contain the alkaloids O-(3,3-dimethylallyl)-halfordinol, N-2-ethoxy-2-(4-methoxyphenyl) ethylcinnamide, N-2-methoxy-2-[4-(3',3'-dimethyalloxy) phenyll]ethylcinnamide, and N-2-methoxy-2-(4-methoxyphenyl)-ethylcinnamamide.

Toxicity

The leaves are said to cause abortion and sterility in women. The bark is used as a fish poison in the Celebes. Tannin, ingested frequently and in quantity over a long period of time, is antinutrient and carcinogenic.

Other Uses

Fruit: The fruit pulp has detergent action and has been used for washing clothes. Quisumbing says that bael fruit is employed to eliminate scum in vinegar-making. The gum enveloping the seeds is most abundant in wild fruits and especially when they are unripe. It is commonly used as a household glue and is employed as an adhesive by jewelers. Sometimes it is resorted to as a soap-substitute. It is mixed with lime plaster for waterproofing wells and is added to cement when building walls. Artists add it to their watercolors, and it may be applied as a protective coating on paintings.

The limonene-rich oil has been distilled from the rind for scenting hair oil. The shell of hard fruits has been fashioned into pill- and snuff boxes, sometimes decorated with gold and silver. The rind of the unripe fruit is employed in tanning and also yields a yellow dye for calico and silk fabrics.

Leaves: In the Hindu culture, the leaves are indispensable offerings to the 'Lord Shiva'. The leaves and twigs are lopped for fodder.

Flowers: A cologne is obtained by distillation from the flowers.

Wood: The wood is strongly aromatic when freshly cut. It is gray-white, hard, but not durable; has been used for carts and construction, though it is inclined to warp and crack during curing. It is best utilized for carving, small-scale turnery, tool and knife handles, pestles and combs, taking a fine polish.

Medicinal Uses: The fresh ripe pulp of the higher quality cultivars, and the "sherbet" made from it, are taken for their mild laxative, tonic and digestive effects. A decoction of the unripe fruit, with fennel and ginger, is prescribed in cases of hemorrhoids. It has been surmised that the psoralen in the pulp increases tolerance of sunlight and aids in the maintaining of normal skin color. It is employed in the treatment of leucoderma. Marmelosin derived from the pulp is given as a laxative and diuretic. In large doses, it lowers the rate of respiration, depresses heart action and causes sleepiness.

For medicinal use, the young fruits, while still tender, are commonly sliced horizontally and sun-dried and sold in local markets. They are much exported to Malaya and Europe. Because of the astringency, especially of the wild fruits, the unripe bael is most prized as a means of halting diarrhea and dysentery, which are prevalent in India in the summer months. Bael fruit was resorted to by the Portuguese in the East Indies in the 1500's and by the British colonials in later times.

A bitter, light-yellow oil extracted from the seeds is given in 1.5 g doses as a purgative. It contains 15.6% palmitic acid, 8.3% stearic acid, 28.7% linoleic and 7.6% linolenic acid. The seed residue contains 70% protein.

The bitter, pungent leaf juice, mixed with honey, is given to allay catarrh and fever. With black pepper added, it is taken to relieve jaundice and constipation accompanied by edema. The leaf decoction is said to alleviate asthma. A hot poultice of the leaves is considered an effective treatment for ophthahnia and various inflammations, also febrile delirium and acute bronchitis.

A decoction of the flowers is used as eye lotion and given as an antiemetic. The bark contains tannin and the cournarin, aegelinol; also the furocourmarin, marmesin; umbelliferone, a hydroxy coumarin; and the alkaloids, fagarine and skimmianine. The bark decoction is administered in cases of malaria. Decoctions of the root are taken to relieve palpitations of the heart, indigestion, and bowel inflammations; also to overcome vomiting.

The fruit, roots and leaves have antibiotic activity. The root, leaves and bark are used in treating snakebite. Chemical studies have revealed the following properties in the roots: psoralen, xanthotoxin, O-methylscopoletin, scopoletin, tembamide, and skimmin; also decursinol, haplopine and aegelinol, in the root bark.