Five finger, also known as star fruit, or Averrhoa carambola, its scientific/botanical name, is a curious, attractive fruit of the oxalis family, Oxalidaceae. This popular fruit tree was named in honour of an Arabian physician called Averrhoes, while the epithet is Spanish in origin.
The fruit is popular throughout the tropics, Southeast Asia, the South Pacific, Micronesia, and parts of East Asia. They remain a local favourite in those areas but have gained popularity in Queensland, Australia, as well as in the Pacific Islands, Latin America, the Caribbean, and the southern United States.
Five finger is an elegant, densely limbed arching and spreading small tree with bright green, lustrous foliage. When in flower, it is very decorative with each slender limb smothered in pinkish red or purplish blooms. It is a vigorous tree that may produce several harvests within a year.
Five finger is a tropical and subtropical fruit which can be grown at elevations up to 1,200 metres (4,000 feet). It prefers full sun exposure, but requires enough humidity and annual rainfall of at least 1,800 mm (70 in). Trees flowers throughout the year and typically produce fruit at four or five years of age.
Fruits are distinctively five-lobed and slice into attractive star-shaped section. It is about five to 15 centimetres (two to six inches) in length and is oval shaped. It usually has five prominent longitudinal ridges but in rare instances can have as few as four or as many as eight. The skin is thin, smooth, and waxy and turns a light to dark yellow when ripe. The flesh is translucent and light yellow to yellow in colour. Each fruit can have ten to 12 flat light brown seeds about six to 13 mm (0.25 to 0.5 in) in width.
The entire fruit is edible and is usually eaten out of hand. They may also be used in cooking and can be made into relishes, preserves, and juice drinks.
There are two main types of five finger: the small sour (or tart) type and the larger sweet type. The sour varieties have a higher oxalic acid content than the sweet type. A number of sweet cultivars have been developed in recent years. In the '80s, a private horticulturist introduced several sweet varieties of five fingers from Thailand into T&T. These varieties were subsequently propagated and now can be found throughout both islands. To maintain the sweet varieties, scion from these trees are grafted onto seedling plants.
Five fingers are rich in antioxidants, potassium, Vitamin C and low in sugar, sodium, and fruit acids. It is a potent source of primary and secondary polyphenolic antioxidants. Averrhoa carambola has both antioxidant and antimicrobial properties and extracts have shown antimicrobial activity against E.coli, Klebsiella spp, Staphylococcus aureus, and Pseudomonas aeruginosa.
It belongs to the oxalis family meaning that fruits contain oxalic acid. Other members of this family include the Bilimbi.
Five fingers contain caramboxin and oxalic acid, both of which are harmful to individuals suffering from kidney failure, kidney stones, or those under kidney dialysis treatment.
Consumption by those with kidney failure can produce hiccups, vomiting, nausea, mental confusion, and sometimes death. Recent research has identified caramboxin as a neurotoxin which is structurally similar to phenylalanine, as well as a glutamatergic agonist.
Despite its toxicity to renally-compromised individuals, the levels of oxalic acid and caramboxin in five fingers are low enough to be safely processed by the general population for whom it is both safe and healthy. It is advised to consult a healthcare practitioner before eating five fingers or its products if taking any kind of pharmaceutical drug.
Ripe fruit can be eaten fresh, sliced into salads and also used as a decorative garnish for food. Given its high oxalic acid content and extreme tartness, fruits are juiced and served as a cooling beverage. Five finger juice is also used as a base for fruit punches and other drinks.
In Hawaii, the juice of sour fruits is mixed with gelatin, sugar, lemon juice and boiling water to make sherbet. Filipinos often use the juice as a seasoning. The juice is bottled in India, either with added citric acid (one per cent by weight) or merely sterilizing the filled bottles for half hour in boiling water. To make jelly, it is necessary to use unripe "sweet" types, or ripe sour types and add commercial pectin or some other fruit rich in pectin such as green papaya, together with lemon or lime juice. Fruits can be processed into pickles and made into chutneys, sauces, wines and jellies. It may also be canned, preserved and dried.
Ripe harvested fruit tend to perish early. However, they stay well in cold storage. Fruit do not ripen or increase in sweetness after being harvested, therefore at the mature turning stage they are best harvested.
Like the bilimbi, the juice of the more acidic sour varieties can be used to clean rusty or tarnished metal (especially brass) as well as bleach rust stains from cloth. They may also be used as a mordant in dyeing.
Five finger trees can also be grown and used for ornamental purposes for its abundant brightly coloured and unusually shaped fruits, as well as for their attractive dark green leaves and lavender to pink flowers. Trees can be easily grown in large pots in the garden. They will remain small and bear fruit. Care should be taken to secure a well-drained soil mixture and pots should be kept in full sunshine and fertilised regularly. If planting in the ground, trees can be pruned to keep them manageable if space is limited.
Five Finger Juice
INGREDIENTS
4 ripe five fingers
Sugar to taste
1 dash bitters
3 cups water (divided).
METHOD
�2 Wash and cut up the five finger.
�2 Blend with 1 cup of water and strain.
�2 Squeeze the pulp to extract more juice.
�2 Add two more cups of water. Add bitters and sugar to taste and stir. Mix well.
�2 Adjust sugar if necessary.
�2 Serve chilled or with ice.
NOTE: You should not drink too much of this juice as it has been known to cause nausea, vomiting, abdominal pain and backache, especially if consumed on an empty stomach.
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This series is written in collaboration with Cynthra Persad, retired director of Research, Ministry of Agriculture. For information on getting copies of the 2 Crops of T&T charts, email fruitstt@live.com
