From the book
Fruits of Warm Climates
by Julia F. Morton
Carambola
Averrhoa
carambola
OXALIDACEAE
A curious, attractive fruit of the Oxalidaceae, the carambola, Averrhoa carambola
L., has traveled sufficiently to have acquired a number of regional
names in addition to the popular Spanish appelation which belies its
Far Eastern origin. In the Orient, it is usually called balimbing,
belimbing, or belimbing manis ("sweet belimbing"), to distinguish it
from the bilimbi or belimbing asam, A. bilimbi
L. In Ceylon and India, the carambola has the alternate names of
kamaranga, kamruk, or other variants of the native kamrakh. In Vietnam,
it is called khe, khe ta, or similar terms; in Kampuchea, spu; in Laos,
nak fuang, or the French name, carambolier; in Thailand, ma fueang.
Malayans may refer to it as belimbing batu, belimbing besi, belimbing
pessegi, belimbing sayur, belimbing saji, kambola, caramba, or as "star
fruit". Australians use the descriptive term, five corner; in Guam, it
is bilimbines; to the Chinese, it is yang-táo. Early English
travelers called it Chinese, or Coromandel gooseberry, or cucumber
tree. In Guyana, it is five fingers; in the Dominican Republic, it is
vinagrillo; in Haiti, zibline; in some of the French Antilles,
cornichon; in El Salvador, pepino de la India; in Surinam, blimbing
legi or fransman-birambi; Costa Rica, tiriguro; in Brazil, camerunga or
caramboleiro, or limas de Cayena; in Mexico, carambolera or caramboler
or árbol de pepino; in Trinidad, it may be called coolie
tamarind. Venezuelans call it tamarindo chino or tamarindo dulce.
Description
The
carambola tree is slow-growing, short-trunked with a much-branched,
bushy, broad, rounded crown and reaches 20 to 30 ft (6-9 m) in height.
Its deciduous leaves, spirally arranged, are alternate, imparipinnate,
6 to 10 in(15-20 cm) long, with 5 to 11 nearly opposite leaflets, ovate
or ovate-oblong, 1 1/2 to 3 1/2 in (3.8-9 cm) long; soft, medium-green,
and smooth on the upper surface, finely hairy and whitish on the
underside. The leaflets are sensitive to light and more or less
inclined to fold together at night or when the tree is shaken or
abruptly shocked. Small clusters of red-stalked, lilac,
purple-streaked, downy flowers, about 1/4 in (6 mm) wide, are borne on
the twigs in the axils of the leaves. The showy, oblong, longitudinally
5- to 6-angled fruits, 2 1/2 to 6 in (6.35-15 cm) long and up to 3 1/2
(9 cm) wide, have thin, waxy, orange-yellow skin and juicy, crisp,
yellow flesh when fully ripe. Slices cut in cross-section have the form
of a star. The fruit has a more or less pronounced oxalic acid odor and
the flavor ranges from very sour to mildly sweetish. The so-called
"sweet" types rarely contain more than 4% sugar. There may be up to 12
flat, thin, brown seeds 1/4 to 1/2 in (6-12.5 mm) long or none at all.
Plate XVI: CARAMBOLA, Averrhoa
carambola
Origin and
Distribution
The
carambola is believed to have originated in Ceylon and the Moluccas but
it has been cultivated in southeast Asia and Malaysia for many
centuries. It is commonly grown in the provinces of Fukien, Kuangtung
and Kuangsi in southern China, in Taiwan and India. It is rather
popular in the Philippines and Queensland, Australia, and moderately so
in some of the South Pacific islands, particularly Tahiti, New
Caledonia and Netherlands New Guinea, and in Guam and Hawaii.
There
are some specimens of the tree in special collections in the Caribbean
islands, Central America, tropical South America, and also in West
Tropical Africa and Zanzibar. Several trees have been growing since
1935 at the Rehovoth Research Station in Israel. In many areas, it is
grown more as an ornamental than for its fruits.
It was
introduced into southern Florida before 1887 and was viewed mainly as a
curiosity until recent years when some small groves have been
established and the fruits have been used as "conversation pieces" to
decorate gift shipments of citrus fruits, and also, in
clear-plastic-wrapped trays, have been appearing in the produce
sections of some supermarkets. One fruit-grower and shipper now has 50
acres (20 ha) planted but suggests that other prospective growers be
cautious as the market may remain limited. Shipments go mainly to
Vancouver, Quebec, Cleveland, and Disneyworld. Small amounts are sold
locally.
Varieties
There
are 2 distinct classes of carambola–the smaller, very sour type,
richly flavored, with more oxalic acid; the larger, so-called "sweet"
type, mild-flavored, rather bland, with less oxalic acid.
In
1935, seeds from Hawaii were planted at the University of Florida's
Agricultural Research and Education Center in Homestead. A selection
from the resulting seedlings was vegetatively propagated during the
1940's and 1950's and, in late 1965, was officially released under the
name 'Golden Star' and distributed to growers. The fruit is large,
deeply winged, decorative, and mildly subacid to sweet. Furthermore,
this cultivar shows the least minor-element deficiency in alkaline
soil, and even isolated trees bear well and regularly without
cross-pollination.
Several cultivars from Taiwan are being grown
at the United States Department of Agriculture's Subtropical
Horticulture Research Unit in Miami, including 'Mih Tao' (P. I. No.
272065) introduced in 1963, also 'Dah Pon' and 'Tean Ma' and others
identified only by numbers, and Fwang Tung' brought from Thailand by
Dr. R J. Knight in 1973. There are certain "lines" of carambola, such
as 'Newcomb', 'Thayer' and 'Arkin' being grown commercially in southern
Florida. Some cultivars and seedlings bear flowers with short styles,
others only flowers with long styles, a factor which affects self- and
cross-pollination.
Climate
The
carambola should be classed as tropical and sub-tropical because mature
trees can tolerate freezing temperatures for short periods and sustain
little damage at 27º F (-2.78º C). In Florida, the tree
survives in sheltered sites as far north as St. Petersburg on the west
coast and Daytona Beach on the east. It thrives up to an elevation of
4,000 ft (1,200 m) in India. In an interior valley of Israel, all trees
succumbed to the prevailing hot, dry winds. The carambola needs
moisture for best performance and ideally rainfall should be fairly
evenly distributed all year. In Australia, it is claimed that fruit
quality and flavor are best where annual rainfall is 70 in (180 cm) or
somewhat more.
Soil
Not
too particular as to soil, the carambola does well on sand, heavy clay
or limestone, but will grow faster and bear more heavily in rich loam.
It is often chlorotic on limestone. It needs good drainage; cannot
stand flooding.
Propagation
The
carambola is widely grown from seed though viability lasts only a few
days. Only plump, fully developed seeds should be planted. In damp peat
moss, they will germinate in one week in summer, require 14 to 18 days
in winter. The seedlings are transplanted to containers of light sandy
loam and held until time to set out. They are very tender and need good
care. Seedlings are highly variable. Air-layering has been practiced
and advocated. However, root formation is slow and later performance is
not wholly satisfactory. Inarching is successful in India,
shield-budding in the Philippines and the Forkert method in Java. Trees
can be top-worked by bark-grafting, a popular technique in Java. For
mass production, side-veneer grafting of mature, purplish wood, onto
carambola seedlings gives best results for most workers. The rootstocks
should be at least 1 year old and 3/8 to 5/7 in (1-1.5 cm) thick. One
Florida farmer prefers cleft-grafting of green budwood and has 90%
success. Grafted trees will fruit in 10 months from the time of
planting out. Mature trees can be top-worked by bark-grafting.
Culture
The
tree needs full sun. A spacing of 20 ft (6 m) has been advocated but if
the trees are on good soil no less than 30 ft (9 m) should be
considered. At the Research Center in Homestead, trees 8 to 10 ft
(2.4-3 m) high respond well to 1 lb (0.5 kg) applications of N, P, K,
Mg in the ratio of 6-6-6-3 given 3 to 4 times per year. If chlorosis
occurs, it can be corrected by added iron, zinc and manganese. Some
advisers recommend minor-element spraying 4 times during the year if
the trees are on limestone soils. Moderate irrigation is highly
desirable during dry seasons. Heavy rains during blooming season
interfere with pollination and fruit production. Interplanting of
different strains is usually necessary to provide cross-pollination and
obtain the highest yields.
Harvesting
and Yield
In
India, carambolas are available in September and October and again in
December and January. In Malaya, they are produced all the year. In
Florida, scattered fruits are found through the year but the main crop
usually matures from late summer to early winter. Some trees have
fruited heavily in November and December, and again in March and April.
There may even be three crops. Weather conditions account for much of
the seasonal variability.
The fruits naturally fall to the
ground when fully ripe. For marketing and shipping they should be
hand-picked while pale-green with just a touch of yellow.
Trees that receive adequate horticultural attention have yielded 100 to
250 or even 300 lbs (45-113-136 kg) of fruit.
Keeping
Quality
Carambolas
have been shipped successfully without refrigeration from Florida to
northern cities in avocado lugs lined and topped with excelsior. The
fruits are packed solidly, stem-end down, at a 45º angle, the
flanges of one fruit fitting into the "V" grooves of another. Of
course, they cannot endure rough handling.
In storage trials at
Winter Haven, Florida, carambolas picked when showing the first signs
of yellowing kept in good condition for 4 weeks at 50º F (10º
C); 3 weeks at 60º F (15.56º C); 2 weeks at 70º F
(21.1º C). Waxing extends storage life and preserves the vitamin
value.
Pests and
Diseases
The carambola is relatively pest-free except for fruit flies. In
Malaya, fruit flies (especially Dacus
dorsalis)
are so troublesome on carambolas that growers have to wrap the fruits
on the tree with paper. Experimental trapping, with methyl eugenol as
an attractant, has reduced fruit damage by 20%. In Florida, a small
stinkbug causes superficial blemishes and a black beetle attacks
overripe fruits. Reniform nematodes may cause tree decline.
Anthracnose caused by Colletotrichum
gloeosporioides may be a problem in Florida, and leaf spot
may arise from attack by Phomopsis
sp., Phyllosticta
sp. or Cercospora
averrhoae.
Cercospora leaf spot is reported also from Malaya, Ceylon, China and
may occur in the Philippines as well. A substance resembling sooty mold
makes many fruits unmarketable in summer.
Food Uses
Ripe
carambolas are eaten out-of-hand, sliced and served in salads, or used
as garnish on avocado or seafood. They are also cooked in puddings,
tarts, stews and curries. In Malaya, they are often stewed with sugar
and cloves, alone or combined with apples. The Chinese cook carambolas
with fish. Thais boil the sliced green fruit with shrimp. Slightly
underripe fruits are salted, pickled or made into jam or other
preserves. In mainland China and in Taiwan, carambolas are sliced
lengthwise and canned in sirup for export. In Queensland, the sweeter
type is cooked green as a vegetable. Cross-sections may be covered with
honey, allowed to stand overnight, and then cooked briefly and, put
into sterilized jars. Some cooks add raisins to give the product more
character. A relish may be made of chopped unripe fruits combined with
horseradish, celery, vinegar, seasonings and spices. Indian
experimenters boiled horizontal slices with 3/4 of their weight in
sugar until very thick, with a Brix of 68º. They found that the
skin became very tough, the flavor was not distinctive, and the jam was
rated as only fair. Sour fruits, pricked to permit absorption of sugar
and cooked in sirup, at first 33º Brix, later 72º, made an
acceptable candied product though the skin was still tough. The ripe
fruits are sometimes dried in Jamaica.
Carambola juice is served
as a cooling beverage. 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 (1% by weight) and 0.05 %
potassium metabisulphite, or merely sterilizing the filled bottles for
1/2 hr in boiling water.
To make jelly, it is necessary to use
unripe "sweet" types or ripe sour types and to add commercial pectin or
some other fruit rich in pectin such as green papaya, together with
lemon or lime juice.
The flowers are acid and are added to
salads in Java; also, they are made into preserves in India. The leaves
have been eaten as a substitute for sorrel.
Food Value
Ripening
and storage studies were conducted at the Florida Citrus Experiment
Station at Lake Alfred in 1966. They found quite a difference in the
acid make-up of mature green and mature yellow carambolas. Fresh mature
green fruits of 'Golden Star' were found to have a total acid content
of 12.51 mg/g consisting of 5 mg oxalic, 4.37 tartaric, 1.32 citric,
1.21 malic, 0.39 a-ketoglutaric, 0.22 succinic, and a trace of fumaric.
Mature yellow fruits had a total acid content of 13 mg/g, made up of
9.58 mg oxalic, 0.91 tartaric, 2.20 a-ketoglutaric, 0.31 fumaric.
In
1975, 16 carambola selections and 2 named cultivars were assayed at the
United States Citrus and Subtropical Products Laboratory, Winter Haven,
Florida. Preliminary taste tests ranked 'No. 17, 'No. 37', 'No. 42' and
'Tean Ma' as preferred. In a later test, 'Dah Pon' was ranked above
'Tean Ma'. 'No. 17' (º Brix 9.9) was described as "sweet, good and
apple-like". 'No. 37' (º Brix 6.7), as "sour and sweet". 'No. 42'
(º Brix 8.3), as "sour, tart and apple-like". 'Dah Pon' (º
Brix 8.0), as "good and mild". 'Tean Ma (º Brix 7.2), as "sweet,
good and mild". Analyses showed that these 5 were among those with
relatively high ascorbic acid content–'No. 17, 30 mg; 'Dah Pon',
30 mg; 'No. 37', 37 mg; 'No. 42', 37 mg; and 'Tean Ma', 41 mg. 'No. 40'
had 43 mg and 'No. 11', 50 mg, whereas 'M-23007' had only 14 mg and
'No. 10' only 17 mg.
Oxalic acid content of the 18 selections
and cultivars ranged from 0.039 mg to 0.679 mg and 4 of the preferred
carambolas were in the lower range as follows: 'No. 17', 0.167; 'Dah
Pon', 0.184; 'Tean Ma', 0.202; 'No. 42', 0.276 mg, but 'No. 37', with
0.461 was 3rd from the highest of all.
Puerto Rican
technologists found the oxalic acid content of ripe carambolas to
average 0.5 g per 100 ml of juice, the acid being mostly in the free
state. They likened the juice to rhubarb juice and advised that
physicians be informed of this because there are individuals who may be
adversely affected by ingestion of even small amounts of oxalic acid or
oxalates. Other investigators have presumed the oxalic acid in fully
ripe carambolas to be precipitated as calcium oxalate or in solution as
neutral salts. The health risk needs further study.
| Food
Value Per
100 g of Edible Portion* |
| Calories |
35.7 |
| Moisture |
89.0-91.0
g |
| Protein |
0.38
g |
| Fat |
0.08
g |
| Carbohydrates |
9.38
g |
| Fiber |
0.80-0.90
g |
| Ash |
0.26-0.40
g |
| Calcium |
4.4-6.O
mg |
| Phosphorus |
15.5-21.0
mg |
| Iron |
0.32-1.65
mg |
| Carotene |
0.003-0.552
mg |
| Thiamine |
0.03-0.038
mg |
| Riboflavin |
0.019-0.03
mg |
| Niacin |
0.294-0.38
mg |
| Ascorbic
Acid* |
26.0-53.1
mg |
* According to analyses made in Cuba and Honduras. |
Amino Acids: (shown in Cuban analyses) |
| Tryptophan |
3.0
mg |
| Methionine |
2
mg |
| Lysine |
26
mg |
Other
amino acids reported by the Florida Citrus
Experiment Station at Lake
Alfred and expressed in
micromoles per g in mature green fruits
(higher) and
mature yellow fruits (lower), respectively, are: |
| Asparagine |
0.92-0.79 |
| Threonine |
0.92-0.79 |
| Serine |
3.88-2.00 |
| Glutamic
Acid |
2.41-1.80 |
| Proline |
0.23-0.09 |
| Glycine |
0.20-0.10 |
| Alanine |
5.40-1.26 |
| Valine |
0.17-0.11 |
| Isoleucine |
0.03-trace |
| Leucine |
trace |
| Phenylalanine |
trace |
| Gamma
Amino Bytyric Acid |
0.77-0.55 |
| Ornithine |
0.11-0.13 |
| Histidine |
trace |
|
**Analyses in India showed 10.40 mg ascorbic acid in the juice of a
"sweet" variety; 15.4 mg in juice of a sour variety.
Ascorbic
acid content of both waxed and unwaxed fruits stored at 50º F
(10º C) has been reported as 20 mg/100 ml of juice. Waxed fruits
stored for 17 days at 60º F (15.56º C) had 11 mg/100 ml of
juice. Unwaxed fruits had lost ascorbic acid.
Other Uses
The
acid types of carambola have been used to clean and polish metal,
especially brass, as they dissolve tarnish and rust. The juice will
also bleach rust stains from white cloth. Unripe fruits are used in
place of a conventional mordant in dyeing.
Wood: Carambola wood is
white, becoming reddish with age; close-grained, medium-hard. It has
been utilized for construction and furniture.
Medicinal
Uses: In
India, the ripe fruit is administered to halt hemorrhages and to
relieve bleeding hemorrhoids; and the dried fruit or the juice may be
taken to counteract fevers. A conserve of the fruit is said to allay
biliousness and diarrhea and to relieve a "hangover" from excessive
indulgence in alcohol. A salve made of the fruit is employed to relieve
eye afflictions. In Brazil, the carambola is recommended as a diuretic
in kidney and bladder complaints, and is believed to have a beneficial
effect in the treatment of eczema. In Chinese Materia Medica it is
stated, "Its action is to quench thirst, to increase the salivary
secretion, and hence to allay fever."
A decoction of combined
fruit and leaves is drunk to overcome vomiting. Leaves are bound on the
temples to soothe headache. Crushed leaves and shoots are poulticed on
the eruptions of chicken-pox, also on ringworm.
The flowers are
given as a vermifuge. In southeast Asia, the flowers are rubbed on the
dermatitis caused by lacquer derived from Rhus verniciflua Stokes.
Burkill
says that a preparation of the inner bark, with sandalwood and Alyxia
sp., is applied on prickly heat. The roots, with sugar, are considered
an antidote for poison. Hydrocyanic acid has been detected in the
leaves, stems and roots.
A decoction of the crushed seeds acts
as a galactagogue and ernmenagogue and is mildly intoxicating. The
powdered seeds serve as a sedative in cases of asthma and colic.
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